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RSS Analysis Meeting Minutes
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07/08/2008
Present : Mark, Oscar, Frank, Karl
- Karl :
- Circulated Draft 1.6 of prl.
- Discussion of the draft led to the following conclusions:
- Oscar points out that Wally's latest paper claims that neutron D-state
correction (1-3/2P_D) is good to the 1% level even at Q2=2 GeV2.
This is very significant to the moments analysis and should be
mentioned in the text. This constant correction also properly accounts
for the effect of tensor polarization in the deuteron.
- The RSS fit curve should be added to Figure 1, evaluated at the data Q2,
and including the fit error band.
- Karl should evaluate the contribution to the integrals in region
1073No need to include all the DIS data in Fig. 1., Simula curve can stay,
no need to include MAID since we are not concerned here with the
x-dependence. Have
to mention that previous prl had an error in g2ww plot.
- Karl should use the fit errors when evaluating the resonance integrals
instead of scaling the data errors to the fit result.
- Mark will send Karl the latest Deuteron F1/R fit.
-
- Oscar :
- Oscar and Shige have been in contact with Wally who has a better
prescription for the smearing needed in the neutron extraction.
Oscar is trying to evaluate if the effect of the new procedure would
have any impact within our error bar. He suggests that the best
way to proceed is to estimate the size of the effect and inflate
our systematic accordingly.
- Wally is working now to extrapolate his results to RSS kinematics.
06/10/2008
Present : Mark, Oscar, Shige (phone), Karl
- Karl :
- Circulated Draft 1.5 of prl.
- Need to define all symbols in Eq. 3. Oscar provides reference for
the original formulation of the OPE expansion of Gamma_1 and Gamma_2:
Phys.Lett.B323:439-445,1994
eqs. 35-38.
- Oscar provides links for many of his previous results to include in the paper:
1
2
3
4
5
- Need to add SLAC neutron and remove MAID curve from Fig. 2.
- Karl is including Mark's D fit into his moments code in order to evaluate
the deuteron moments and compare with Oscar.
- Oscar notes that his DIS fit to deuteron data has better uncertainty than his
neutron fit, so Karl should use the deuteron fit.
- Oscar's value for f2 comes from integration of the fit, with data error propogated
as a percentage of the central value. He concludes there is very little twist-4,
atleast within our huge errors. We need to compare our results to previous publications. The DIS contribution is twice as big as our measured resonance value.
- Oscar points out that there should be an error associated with the value of gamma_D
quoted in our paper.
- Shige :
- In communication with Wally about the neutron extraction. Wally wanted to know
what smearing method Shige used (=Atwood-West).
- General :
- Next meeting : Tuesday June 24 1:30.
06/03/2008
Present : Mark, Oscar, Shige (phone)
- Shige :
- Contacted Wally and he gave us MAID xg1 and xg2 at Q2=1.0 and 2.0.
According to Karl, Wally seemed to be using MAID 2000 while Karl was using
MAID 2003. Karl found a new version (MAID 2007) and downloaded it. He
believes that the new one will not give us much impact on the MAID
integrals.
- Wally also kindly gave us his calculations of the ratio R = g1d/g1N of
structure functions for the full model used in his paper (PLB 346, 165
(1995) ). It turns out the values he gave us are pretty close to what we
have (differ by ~1% or so). So, the neutron results will not change much.
Wally said he doesn't believe that his calculations are valid at low Q2:
What we can do is to do the D-state correction in two different ways
(using a constant depolarization factor and using Wally's calculations),
and report the difference in neutron results as systematics.
05/08/2008
Present : Mark, Oscar, Shige (phone), Karl
- Karl :
- Circulted draft 1.4 of the moments paper.
- Specific suggestions made: Eqs. 1 and 5 can be simplified.
- Text really only applies to proton for now, it needs to be generalized.
- For Deuteron, do we include QE contribution to evaluate `nuclear' sum
rules, or stick with proton, neutron, singlet and non-singlet results
above pion threshold? It seems like the second choice is more realistic
as we might need several more months analysis to clean up the deuteron
QE results. Also, it would be difficult to make the paper general enough
to cover both nucleon/nuclear sum rules.
- Oscar points out that we have to use Wally et al's x-dependent D-state
correction, and reference it in our paper. It only deviates by about
13 percent from the constant correction, and then only for our highest
x point. More details on Shige's page (April 10,13 and 23 of 2007).
- Mark points out that all the plot curves are not explained in the text.
Also, each of the Table entries is not really discussed yet either.
Fig. 2 should also include g2d, then it will provide our measured quantities.
The introduction needs explanation of neutron extraction, and x-dependent
D-state correction.
- Oscar requests description of singlet, non-singlet, etc. be put back in
the table.
- Oscar will provide M13 calculation, and reminds Karl to include f2 in paper.
- Shige:
- Has been discussing with Wally about the apparent difference in MAID
model results between his paper and RSS. He will request Wally's MAID
results at Q2=1,2 GeV2 (before interpolation) so we can directly compare
to our table. This should resolve whether it is just an interpolation
problem or if the two models really disagree.
- Shige is working on draft outline of long paper and will try to post
it by the end of next week. Oscar suspects that we have planned to
include too many things in the paper and may have to cut out some topics.
04/15/2008
Present : Mark, Oscar(phone), Shige (phone), Karl
- Karl :
- Circulated updated manuscript for moments paper.
- Oscar has no major comments, but will forward some suggestions to Karl.
- Mark suggests to include a g2p plot or possibly a plot with both
g2p and g2D (g2n?). Might be good way to correct the g2ww result on our g2p plot
from previous prl instead
of an erratum.
- Oscar points out that there is already a discussion of the low x part of g2p and
g2ww on page 4, in his section on higher twist. Suggests to move this to
the BC sum rule section.
- In d2 section just need to refer to earlier discussion and give error values.
- Karl points out that nachtmann moment machinery is primarily useful to enable
clean higher twist extraction. Shouldn't we use them to do so to get f2?
- Oscar has already extracted f2, and will recirculate the result. If we have
enough room we can put it in the prl.
- Karl notes that two papers with heavy theorist input extracted higher
twists without using Nachtmann moments even though g2 data was available.
Oscar notes that the largest effect is in the M23 (d2) moment. The M11 (Gamma_1)
integral has a smaller effect. So this may be why the papers Karl reference
don't use nachtmann moments. In addition, Simula and Piccione & Ridolfi have made
very strong statements that the nachtmann moments must be used for clean extraction
of dynamical higher twists. Finally, Oscar points out the limitations of using
the scaling variable x_bj in our kinematic region: Nachtmann variable is really
more appropriate for any Q2<2 GeV2.
- Karl working to round up all results that Oscar has evaluated for the moments
that are spread over several different emails, for incorporation into the paper.
- Oscar requests additional column added for deuteron systematics.
- Shige suggests change to abstract : ``neutron from deuteron'', instead of neutron (deuteron).
- Shige:
- In discussion with Wally regarding the Maid model results used in his paper which
seems to place the delta at a different x (0.67 instead of 0.63) than we expect.
- Also the highest shown model x is much less than what is seen in the data.
- Our previous plots of MAID seem very different than what is in Wally's paper.
- Shige working on the long paper, Oscar suggests to circulate a rough draft with
placeholders for the unfinished sections.
- General:
- Next meeting : Thursday May 8, 1:30 pm
04/03/2008
Present : Mark, Oscar(phone), Shige (phone), Karl
- Karl :
- Evaluated DIS part of M11 Nachtmann moment using the Bianchi-Thomas parameterization.
(See Oscar's Feb. 27 email for further details.)
- Find's results that are within a few percent of what Oscar's g1 fit gives.
- There remains a large discrepency in the integral that depends on g2WW. Karl
believes this is because Oscar produced g2WW from his DIS g1 fit, while
Karl produced it from the RSS resonance fit. He will evaluate again using
the DIS fit.
- Oscar asks Karl to also evaluate the integrals for the deuteron. Bianchi-Thomas
provide a proton and a neutron so Karl will combine to form a deuteron
(only correcting for the d-state).
Oscar points out that there is no need (or possible method) to perform Nactmann moments for Gamma_2 which is not part of the OPE.
CN moment is all there
is for Gamma_2. There is no M21 which is what you'd need for Nactmann B.C.
Oscar finds that the overall Nactmann moment for Gamma_1 not much different
from the CN moment. This is in contrast to what Dong finds for the d2 (M23)
integral in which the nactmann correction is quite large at our Q2.
- Karl has been working on the prl draft. Incorporated about 70% of comments provided by
Oscar.
- Mark suggests discussing TMC earlier in the paper, during the introduction
to Cornwall-Norton moments. Will help in explaining the motivation for
using Nactmann moments.
- Mark suggests including Gamma_2 plot, and notes that the discussion of GDH integral needs work.
- Table should have similar results for Gamma_1 (Singlet, Non-Singlet, proton, deuteron, neutron) and Bjorken Sum Rule.
-
- Oscar :
- Has numerical values for everything except Gamma_2 for the deuteron. Bjorken
integral seems almost completely insensitive to TMC (CN = Nactmann moments).
Gamma_1 integral shows very little difference also between CN and Nactmann.
- Shows summary table with numerical values.
- In the paper, we will include the Nactmann values if space permits, otherwise
just discuss that they are very close to the CN moments and point out why.
Oscar sent email to Karl yesterday suggesting how to phrase this.
- Oscar also extracted an effective \alpha_s from our Bjorken integral. The
results have pretty good uncertainty compared to the world data.
- Shige :
- Discusses paper of Kulagin and Melnitchouk. In it, the authors form a deuteron
from the MAID Proton and Neutron after applying nuclear corrections. The paper
is at Q2=2 GeV2, so Shige contacted the authors and got the results at Q2=1.3 GeV2
to compare with RSS data.
- Shige shows the comparison to RSS which is not very close. In particular, it
does not seem like even the Delta lands at the same x_bj in data and calculation.
Also, the maximum x_bj in the calculation is about 0.75 while the data goes
to x>0.8.
Shige will show to Wally to get some comment.
- Shige is also working on the long paper.
- General :
- We will meet next on Tuesday April 15 at 1:30pm.
03/13/2008
Present : Mark, Oscar, Shige (phone), Karl
- Karl :
- Incorporated Oscar's higher twist section into moments paper,
and restructured the paper to follow the outline agreed upon last meeting.
Also converted references to bibtex. Goal is still to have paper ready for the arXiv
in April.
- Oscar asks Karl to finish work on DIS part of g1 (Nachtmann moment of the B.T. function). See Oscar's Feb. 27 email for further details.
- Oscar :
- Discusses his moments technical note, and clarifies some variation in notation
between authors.
- Oscar points out that there is a typo in his note: \delta d_2^{DIS} should just be d_2^{DIS}.
- Believes we should show BC sum rule plot with both proton and neutron in the paper.
- Oscar is reviewing the primary reference for the ELT sum rule and will forward
it to Shige for discussion in the long paper.
- General :
- We will meet next on Thursday April 3 at 3:30
02/20/2008
Present : Mark, Oscar, Shige (phone), Karl
- Oscar :
- Suggests new structure for the moments paper:
- Intro : Moments, sum rules and matrix elements. Non-OPE Sum rules : BC and Bjorken.
Definition/comparison of C.N. and Nacthmann moments. Target Mass Corrections.
- Results for First moments of g1 : Gamma_1^p, Gamma_1^D,Gamma_1^Sigma,
Gamma_1^NS,Gamma_1^N,Bjorken,I_GDH.
- Subsection to discuss elastic contribution and why we don't need to include.
- Results for First moment of g2 : BC
- Third Moments : d2^p,d2^D,d2^Sigma,d2^NS,d2^N
- Subsection on Higher Twists and polarizabilities : f2
- Second Moments : ELT using fits only, Valence region. This section may be
better suited to the long paper.
- Karl will work on Sections 1-3. Oscar will work on Sections 4,4a. Section 5
may be moved to Shige's long paper.
- Oscar requests Karl to evaluate DIS contribution to Nachtmann moments.
- Oscar suggests "We present (first?) evidence for dynamic higher twists" to
be added to the abstract.
- Regarding long paper: Shige will evaluate ELT sum rule in long paper. Oscar
will send us all the relevent ELT reference.
- Shige is working on his sections now. Oscar requests that Shige compile
together all the sections he has recieved so far into an initial rough draft.
We agree to use bibtex for citations, and Mark will establish a CVS repository
for the document so we can efficiently make changes.
- Next Meeting : March 11
02/19/2008
Present : Mark, Oscar(phone), Shige (phone), Karl
- Shige :
- Working on error propagation for g1p,g2p. After discussion, it appears
that Shige's work from April 02, 2007 is sufficient and nothing more is needed.
This was the last piece of analysis for Shige.
- Oscar :
- Releases new version of his moments technote.
- Points out that there does not appear to be any twist-3 visible in our g2p at low x.
- Expects that the two different formulations of d2 (equation 17) will agree when
they are evaluated at constant Q2. Oscar will verify.
- Oscar has obtained estimate of the DIS contribution to d2.
- Concludes that we see twist-3 effect to 3 sigma in proton and 2.5 sigma in deuteron.
- General discussion on how to structure the moments paper. Seems best to
try to put first and higher moments into one paper. If it does not fit
it can be moved to second paper or to the long paper.
- Introduction to moments paper should contain brief discussion of d2 and
Nachtmann moments. For example, Eq 10 of Oscar's TN can be shown and
then demonstrate how it reduces to C.N. moment.
- Oscar requests that we all recheck our responsibilities for the long paper
and send any outstanding material to Shige.
01/08/2008
Present : Mark, Oscar(phone), Shige (phone)
- Oscar :
-
Found an error on our published g2ww_p result.
calculated g2WW for proton and deuteron. Both approach toward zero at low
x, so this makes more sense. (see his email sent
yesterday for details). Discussed how we should report this error and
we prefer to mention this in our new upcoming paper rather than
publishing an erratum. But Frank was not at the meeting, so we
don't know his opinion.
- Shige:
- Will recalculate the smeared proton errors as his approach (apr02, 2007)
looks incorrect. Will also update the neutron errors. As suggested by
Oscar, dg1/g1 and dg2/g2 are calculated easily knowing the delta_F1/F1
of ~3% and the data fit errors (dA1 and dA2) for each w bin.
- Recalculated the deuteron DF systematics due to nucleon model.
(the results posted on oct 30, 2007 were wrong because an incorrect
version of MC was used.) see Shige's webpage dated dec18, 2007
- General:
-
Next meeting will be on Jan 29.
11/29/2007
Present : Mark, Karl, Oscar(phone), Shige (phone)
- Shige
- Final systematic : 6% on Deuteron DF.
- Karl
- Running the simula model to compare with data.
- Will work on paper over holiday and after PAC.
- Mark points out that there is a way to submit to prl from the arXive which
preserves the citations.
- Goal is to have someting on the ArXive by April.
- Mark favors 1 PRL, not two papers.
- Oscar
- Points out some ambiguities in the references. For Bjorken sum rule
gv/gA evolved to Q2=5, must use the PDB value divided by 6:
Gamma_1^N-Gamma_1^P = gA/6
- Oscar has a link to website for getting alpha_s at any scale.
From alpha_S, can derive Lambda_QCD.
- We should be assuming two flavors, since charm threshold is near Q2=1.3.
Oscar points out that NF,Lambda,Beta are all scale dependent,
but there is very small change withing error.
- Oscar has 3 parameter fit to SLAC deuterium with good chi2 for use in Bjorken.
- Not certain whether to use LO or NLO alpha_S.
- Believes we should use Nachtmann moments instead of C.N. moments.
- General :
10/30/2007
Present : Mark, Karl, Oscar(phone), Shige (phone)
- Oscar :
- Updated RSS configuration
- Changed VNC configuration to use 256 instead of 16 colors. We should now
be able to use acroread properly.
- Going over long archive paper.
- Trying to incorporate his work into systematic section.
- Suggests some modifications to Shige's outline. Mark modifies the
posted outline with new suggestions and to reflect the responsible person
for each section. Also restructures the systematic section.
- Oscar will add some background definitions to the asymmetries section to
make it more appropriate for a general target.
- Shige :
- Working on the deuteron DF systematic study.
- Evaluated the uncertainty due to nucleon model, but would like to recheck.
- Discussion of the "B-factor" in propogation of deuteron DF systematic. Oscar
believes Shige can probably use the proton "B-factor", since it will be
an overestimate. From Feb. 09, 2006 webpage B=1.
- General :
- Shige will be out of country. We will meet next on Nov. 27th.
10/17/2007
Present : Mark,Frank, Karl, Oscar(phone), Shige (phone)
- Oscar
- What to do with Wilson Coefficients? Nothing, unless we want to compare
measurements at different kinematics. For example, RSS vs SLAC, or if
we want to correct our data.
- d2 can use only 2 flavors : u and d. Oscar prefers we use two flavors
for RSS, 3 for SLAC.
- No corrections to d2 at leading order. Our prl values is fine.
- Oscar discusses the various contributions to the nachtmann moments from
different kinematic regions.
- Oscar recommends a book from T. Mutan (Reference 8) to understand QCD.
- Notes a large discrepency with SLAC deuteron d2 Nachtmann moment. Indicates
something wrong with SLAC or us, but Cornwell Norton moment agrees???
- Oscar asks Karl to verify his moment calculations.
- For d2, we can use g2ww to estimate uncertainty, but can not use it
to estimate unmeasured part directly (d2 has no twist-2).
- Final word on RSS d2 : "3sigma indication of higher twist", "1st measurement
ever of definite higher twist".
- Regarding the long paper: Oscar incorporated Shige's new systematic errors,
and is working on the target section. Mark suggests reorganizing the
systematic discussion. Karl will send Oscar discussion on the R.C. systematics.
- General :
- Next meeting in two weeks : 10/30/2007
09/25/2007
Present : Mark,Frank, Karl, Oscar(phone), Shige (phone)
- Shige
- Has completed the Deuteron dilution factor systematic study.
- Provided result to Oscar and Frank.
- Oscar
- Discusses topics for the moments prl.
- Oscar points out that d2 is pure twist 3, so it is incorrect to estimate the
missing low x contribution using g2ww(twist-2) as Karl has been doing.
- Oscar notes that at low x our g2 data is consistent with g2ww, so that
we can assume that the twist-3 part is zero (ie there is no DIS contribution to
d2). Then we can use the result of the g2ww integration as an estimate of the
systematic uncertainty.
- Oscar added a new section on this topic to his note, along with a section on the
flavor structure of the 3rd (and higher) moments.
- He proposes that we evolve our d2 up to the asymptotic value instead of
vice versa as we have been doing in the plots. Similarly for Bjorken: we may
find that we have a very competitive error bar.
- Regarding the moments paper, Oscar proposes the following structure:
- Karl's intro
- 1st moments Gamma_1, Gamma_2 and Bjorken. Both Cornwell-Norton and Nachtmann.
- Higher twist
- If space permits, a further section on Efraemov-Teryaev sum rule.
- Oscar will repost an updated version shortly.
- General
09/04/2007
Present : Mark,Frank, Karl, Oscar(phone), Shige (phone)
- Oscar
- Produced first draft of moments technote focusing on the QCD
radiative corrections, Nachtmann moments and NLO corrections (section in
preparation).
- Basic conclusion : Oscar believes that our Nachtmann results don't need
any QCD corrections: they are fine at LO. The Wilson coefficients are
used to relate measurements at different Q^2, so we can use them to
evolve from SLAC down to RSS or vice versa (assuming pQCD works), but
our results are just fine as they are in LO.
- Ji et al. have also worked out the NLO corrections, which would help us
in getting a better value for the asymptotic d2 from our measured one.
Oscar is working out the proton and neutron results
from the singlet and non-singlet ones that are provided in Ji's papers.
- Oscar requests comments on the draft. He plans to circulate among a few theorists also.
- We will incorporate a summary of this work into the letter.
- Oscar points out that there is several different conventions relating G1,G2 and g1,g2
in the literature. This can lead to significant error if not treated properly, of the
same order of magnitude as the "standard" corrections : TMC, low-x resummation....
- Shige
- Working on draft of long paper.
- Using this opportunity to organize his study of Packing Fraction and other systematics.
- Karl
- Preparing talk for crimea2007.
- Several suggestions/comments for Karl's presentation are discussed.
- Oscar has some comments for the moments letter: would like us to include Bjorken and
ELT sum rules. For this we may need a fit to the neutron data.
- Frank
- Will produce systematic error bars for deuteron from Oscar's tables. Needs
final Deuteron D.F.
- General
- We will meet again on Sept. 25.
08/14/2007
Present : Mark,Frank, Karl, Oscar(phone), Shige (phone)
- Karl
- Updated proton RC section for long paper.
- Circulated first draft of moments prl.
- Shige
- Updated neutron results with Mark's new Deuteron fits. Did not change much.
The changes in the fit arose from the TE/calibration constant. There was a small variation
in the error for g1n.
- Shige finds g1,g2~0, except for one point at x=0.65 which is about 3 sigma from zero.
He has posted a table of his results.
- Expects to have packing fraction yields by next week.
- Oscar
- Working on g1d duality. Finds good agreement for global. Also split the region in
two for a limited local test : 1.09Oscar discusses several theory papers relevent to RSS. He is working on a technote
to summarize what he has found.
- General
- We now move to bi-weekly meetings.
07/31/07
Present : Mark, Karl, Oscar(phone), Shige (phone)
- Karl
- Updated moments technote to reflect recent comments from Oscar.
- Posted first draft of proton RC section for long paper.
- Shige
- Working on updating his neutron results.
- Progress interrupted by JLab network failure.
- Oscar
- Wrote target section for long paper. Mentions that best source he has
found after reviewing old papers is from Mark's elastic paper.
- Suggests that Shige should not worry too much about the exact formatting
requirements of PRC for this initial draft.
- Oscar has evaluated duality integrals for the deuteron using the GRSV and
AAC tables from Peter at Q2=1.2 and Q2=1.4 GeV2. He interpolates these
results to RSS kinematics.
- Global duality looks good (although partially this is due to larger deuteron errors).
- He will look at some limited local duality integrals over a restricted W range.
- Oscar has also evaluated d2D and d2n. d2n is now consistent with world data,
although with quite large uncertainty.
- Also evaluated the systematic errors for Gamma_1^D and d2D. They are slightly
larger than the corresponding proton errors.
- Oscar is considering what we should publish of the higher moments beside d2.
- He is also working on a technote to discuss the moment's logarithmic QCD corrections.
So far, he has concluded that we do indeed need to evaluate the Wilson Coefficients
as described in S. Matsuda and T. Uematsu. He believes the discussion in the
Ji paper refers only to the BC sum rule.
- Oscar may not be available to meet next week.
07/17/07
Present : Mark, Karl(phone), Oscar(phone), Shige (phone)
- Oscar
- Applied fits to Deuteron to get sum rules, d2 and duality integrals. Not quite finished.
- Oscar is finding d2n approximately zero.
- Oscar recommends that we set the DIS part of the A2D fit to constant if we use
a constant value for A2D.
- Finds d2D=0.0048, with very little dependence on Q2 evolution. Compare to our proton
d2p=0.0057. When deuteron is corrected by D-state correction we get d2D approximately
equal to d2p. So d2n is about zero, but slightly negative.
- This is very different from what Karl found for d2n
(see 01/16/2007) with Shige's early neutron
results. The old results where consistent with the hall A results, and Slac results
within error.
- Oscar: It's not clear we are doing anything wrong, but we have to understand this.
- Shige notes that he is now using Peter's F1, which is per nucleus.
- Oscar has begun to evaluate the deuteron duality integrals. He has GRSV and AAC from
Peter (tables at Q2=1.2 and 1.4 interpolated to RSS), but he does not have Soffer's
statistical model for deuteron. Oscar doesn't believe it is necessary to have too many
PDFs for Deuteron, since we found there is relatively small differences among versions for proton.
- Oscar is now using the fit instead of data values to evaluate the systematics that are
proportional to central value. But, this still hasn't smoothed out the sytematic fluctuations,
in fact it made it worse.
- Oscar points out that we need to evaluate the ELT sum rule.
- Karl
- Posted "final" table of proton moments, and moments technote.
- Found 15% relative error on Gamma_2 DIS contribution. This is larger than
what Oscar had recommended, but only slightly larger than the Gamma_1 DIS
error.
- Added theory discussion and introduction which can serve as starting point for PRL.
- Shige
- Working on long paper.
- During general discussion sections of the paper are assigned to group members. It is
agreed that we should all have a draft of our relevent contributions ready in two weeks.
The assignments are:
- Experimental description: Mark.
- Polarized Target : Oscar.
- P.F. : Shige.
- Engine : Frank.
- Proton RC : Karl.
- Nitrogen Correction: Mark/Oscar.
- Fit to Data : Oscar/Frank.
- Deuteron analysis and results: Shige.
- Deuteron RC : Mark.
- Smearing and Neutron Extraction: Shige.
- Systematics : Oscar.
- We will meet again in 2 weeks: July 31.
07/03/07
Present : Mark, Karl, Oscar(phone), Shige (phone)
- Oscar
- Working on the deuteron systematic. Noticed that the systematic is very "jumpy".
This is because some of the errors are directly proportional to the asymmetry which
has large statistical fluctuations. Oscar notes that we will publish results
in 45 MeV bins.
- Karl suggests to use the fit instead of the data to avoid statistical fluctuations
in the systematic error.
- Oscar mentions that the new UVA postdoc is Vladis T. He will start in September.
- Reading the paper of Song et al. He is confused by the discussion just after
eq. 28 "... the combination of gT and g1 relevant to d2
receives no radiative correction." Does this mean we don't need
to evaluate the Wilson coefficients? Oscar requests that we read the paper
so that we can discuss.
- Shige
- Working on Deuteron dilution factor systematics.
He contacted Peter, who estimates
the deuteron model uncertainty is 5% (3-4%) in the quasielastic (inelastic) region.
- Shige is following the same procedure as for the proton: He increases the cross section by
the uncertainty and then observes the change in the packing fraction (about 1%).
He then reevaluates the dilution factor with the new values. Dilution factor
changes by 2.6% (2.5%) for the parallel (perp) setting.
- Also looking at the small uncertainty due to run selection.
- Shige is very busy with new job, but still working on RSS in his spare time.
- Mark
- Is up to date on all his RSS tasks.
- Karl
- Updating his moments note and data table.
- Planning to have draft publication in July.
- Oscar points out we should evaluate the ELT sum, and compare to hall A.
- Oscar requests that Karl relay to his hall A collaborators the utility of
producing a fit to the hall A data which can be evaluated at any Q2.
06/26/07
Preparation for SANE readiness review. No RSS meeting.
06/19/07
User Group Meeting. No RSS meeting.
06/12/07
Present : Mark, Karl, Oscar, Shige (phone)
- Shige
- Following Peter's suggestions to evaluate deuteron systematics. Now running jobs on
the farm. Peter claims 3-4% uncertainty on the inelastic deuteron model, and 5% in
the quasielastic. These are the values Shige will use in his DF calculation.
- Shige needs about 4GB of disk space for his work. Mark will move some of the Bigcal
files.
- Shige is following the procedure outlined in his Feb. 09, 2006 webpage entry.
- Oscar expects 4.5-5% uncertainity.
- Mark
- Since there are new Deuteron polarization values, he redid the A1, A2 fits. Notes that Shige
should use new fit parameters that Mark posted on his webpage. Shige will update.
- Mark sent an email regarding the fits to the RSS group.
- Oscar
- Shows graphical errors on deuteron g1,g2.
- Compares the deuteron systematic to previous proton result. The deuteron systematic
is slightly worse than the proton.
- Oscar expects to have the uncertainty on Gamma_1, Gamma_2 next week, then we should
have all the ingredients for the papers. The goal is to have drafts of both
papers in July.
- Oscar has been looking through a paper of Ji et al, for the needed Wilson coefficients.
- Points out an error in the paper of S. Matsuda and T. Uematsu. They were looking only
at 3 quark operators, and neglected gluon operators. Ji et al. reanalyzed and have
values for the singlet and non-singlet case. From these we can get the neutron and
proton coefficients.
- The other option is to just quote the ratios and not explicitly evaluate the coefficeients (example M23).
- Papers: X.D.Ji, W.Lu, J.Osborne and X.T.Song,
``One-loop factorization of the nucleon g2 structure function in the
non-singlet case,''
Phys. Rev. D62, 094016 (2000)
and
A.V.Belitsky, X.D.Ji, W.Lu and J.Osborne ,
``The singlet g2 structure function in the next-to-leading order,''
Phys. Rev. D 63, 094012 (2001).
- No meeting for two weeks, until after SANE readiness review.
06/05/07
Present : Mark, Karl, Oscar
- Mark
- Working to incorporate the change in deuteron polarization due
to new T.E. values into the RSS analysis.
- Reran Frank's script to produce updated asymmetries.
- Redid the deuteron radiative corrections.
- The polarization is 3% lower than what we thought previously.
- Oscar
- Performing additional systematic studies.
- Oscar points out that the Nitrogen asymmetry correction is larger in ND3 than in NH3.
- Oscar has requested that Shige evaluate the deuteron dilution factor systematic.
- Still need to evaluate the contribution from F1, R. Oscar expects he will need a few weeks to finish
this.
- Oscar mentions that he is reading a very instructive early paper by Nachtmann "Is There Evidence for Large Anomolous Dimensions?"
Nucl.Phys.B78:455,1974.
05/29/07
Present : Mark, Frank, Karl, Oscar(phone), Shige(phone)
- Oscar
- Reviewing the Deuteron T.E.'s to determine systematic. Oscar found that the standard
deviation of the results was about 10%. Assuming we know GEP to a few %, the we would get smaller systematic from Q.E.
asymmetry. But this would require detailed study of the Deuteron dilution factors
in the QE region.
- Oscar's results: Bottom Para gives 10% syst from standard deviation of T.E.s, slightly smaller value from the absolute deviation. Bottom Perp : 3.6% variance. Top para: 4%.
- In regard to Frank's g1d experiment, Oscar mentions that the GEN experiment achieved 2.5% uncertainty on polarimetry, but
it required detailed study. Also, the deuteron target can take 150 nA easily. The
RSS target average was 120 nA.
- Oscar has also been doing some further research into target mass corrections.
05/22/07
Present : Mark, Karl, Oscar, Shige(phone)
- Oscar
- Discusses his spreadsheet used to evaluate deuteron systematic errors. The spreadsheet combines
the radiative correction systematic with all remaining errors. Work in progress.
- Oscar is following the same procedure as with the proton. However, Pb and Pt will
be separate contributions.
- He is using the 12 configurations of RC results that Mark provided to evaluate RC syst.
- In general, he finds something like a few percent RC error for inelastic, and a slightly
larger error at low W.
- For total systematic, he finds a similar trend: several percent uncertainty everywhere, but rising to 10-12% at low W.
- The statistical errors are generally much larger than the systematic.
- Oscar needs reasonable numbers for the polarimetry uncertainties in order to complete his work. He reviews the deuteron T.E. data which suggests 6-8% systematic for the target polarimetry.
- With regard to the moments paper, it is not clear how we can evaluate the Wilson coefficients that are discussed in the S. Matsuda and T. Uematsu paper.
We should publish M23 (=Wilson coefficient * d2).
- Sum rules paper should include Bjorken non-singlet, ELT sum rule.
- Shige
- Rechecking his codes.
- Lots of training to go through for his new job.
05/15/07
Present : Mark, Karl, Oscar (phone), Shige (phone)
- Karl
- Evaluated M23, and M11 integrals to compare to Oscar's earlier result.
- Seems to be factor of 2 problem with the error when compared to Oscar. Both will recheck their results.
- Oscar
- Oscar's conclusions: Plenty of real twist-3 in our data. The TMCs contribute less than 1/3 of the Cornwall-Norton result.
- Oscar summarizes Dong's new paper: "To properly treat target mass effects, use nachtmann variable as discussed in the S. Matsuda and T. Uematsu paper." Integrals such as Int g1 dxi (where xi is the nachtmann var) are meaningless.
- Need to evaluate the Wilson coefficients E1N,E2N.
- We may need to mix the neutron/proton results to get singlet/non-singlet pieces.
- Dong/Matsuda and Uematsu are the first believable treatment of Higher Twist in spin structure functinos.
- Frank: How difficult will it be to persuade others that this is the proper treatment? Oscar: Matsuda and Uematsu paper is a classic, nobody questions the approach.
This is a good approach for any experiment which measures both g1,and g2. The
only reason it was not applied before is because of lack of g2.
The Ridolphi and Piccuni paper, along with Matsuda and Uematsu clarifies all issues.
- Oscar is working on the Deuteron systematics. It is straightforward but tedious.
- We should include M23, M11 in our sum rules paper, in addition to standard moments.
- Mark
- Found that varying A2 model in the Radiative Corrections has very little effect, only varying A1 matters.
- Shige
- Produced an outline of the deuteron/neutron long paper.
- This will also be the long paper of the experiment. It should contain the final proton results, but no need for further discussion.
- The detailed theory discussion should focus on neutron extraction.
- Probably will only be able to evaluate global duality integrals, not local.
- Sum rules paper should have more theory.
05/08/07
Present : Mark, Karl, Oscar (phone)
- Mark
- Testing the deuteron RC systematic by varying the A1,A2 fits by their errors
during the RC procedure. Mark evaluated 12 different combinations that arise
from the follow possibilities:
A1, A1+dA1, A1=dA1. A2(constant), A2(constant)+dA2,A2(constant)-dA2.
A2(fit), A2(fit)+dA2,A2(fit)-dA2.
- Will provide these results to Oscar.
- Oscar
- Working on d2 and target mass corrections.
Reading the new Stamenov and Siderov preprint.
- Oscar mentions that Dong's latest paper advocates using the
TMC method proposed in 1980 by S. Matsuda and T. Uematsu.
Nucl. Phys. B168, 181 (1980).
- Comparing various versions of R to what Peter's code uses for Deuteron. Oscar
sees a very large difference among R's at low W. This will increase the systematic.
- Points out that the relevent Wilson coefficient must be included in order to
compare data to Dong's prediction of d2.
- Karl asks if Oscar's Gamma_1p systematic study can be applied to Gamma_2p. Oscar
will look into it.
- Oscar shows a study he performed evaluation d2 with the Nachtmann variable, with
zero and nonzero mass. He concludes that the target mass corrections are small. In
particular, Karl can use Scenario I for his Gamma_2 DIS estimate. The g2WW formed
in this scenario only has a 10% contribution from target mass corrections. The
rest is twist-2.
- Oscar now looking into the issue of "higher spins".
- Karl
- Working on including LSS, BB pdf's in his code for evalution of Gamma2_DIS estimate.
04/30/07
Present : Mark, Karl, Oscar (phone)
- Mark
- Worked on Deuteron RC systematics. First he tried to vary the DIS fit form
as discussed last meeting. But he found that there was really no significant
variation in the total fit anywhere but at threshold. So now he is going
to vary the A1 and A2 fits by their error bands. Mark will look at the following possibilities:
Hold A2 fixed at a constant value and vary A1, Hold A2 fixed with a functional form and
vary A1, Hold A1 fixed and vary A2 by its error band.
- Karl
- Discussion on error from g2 integral Dis contribution. Conclusion: Karl should use
"Scenario I" to form g2 DIS integral, as was done in E94010 and E155x. Then
estimate the error strictly from variation of PDFs, no Regge fits. Oscar
suggests to normalize the PDFs in the resonance region to the ratio of PDF to Regge fit
in DIS. This is due to the fact that the TMC PDF's do not match the data even
at low x. Also, Karl should include more PDFs, LSS in particular, but maybe also BSB.
- Karl : if we normalize the PDF's to match world data, then shouldn't we do that
also for our duality integral?
- Oscar
- Looking at Dong's newest paper with Mark. They would like to discuss several issues
with Wally. In particular the relationship between the a2(3?) matrix element, and
the explicit calculation of TMCs.
- Oscar has found that in the rush to publish PRL, we underestimated the contribution
to the
sytematic from the elastic tail. It is a pretty small effect and will only effect
the PRL plot near threshold. No effect on any published numbers.
04/23/07
Present : Mark, Karl, Frank, Shige(phone), Oscar (phone)
- Shige
- Posted datafiles for g1,g2 proton(smeared), deuteron, and neutron.
- Using F1,F2 from Peter's code which is for free F1,F2. Shige needs
smeared F1,F2.
- This week Shige produced A1n, A2n from g1n, g2n.
- Talked to Peter regarding the smearing of F1,F2. He modified Peter's
code F1F2INEL.f to give smeared quantities.
- Shows comparison of his latest A1n, A2n to what he found last year. At that time
he did smearing on DeltaSigmas. Now he forms A1,A2 directly from g1,g2.
- Shige is assuming an arbitrary 10% uncertainty on F1n (smeared). Will spend
some time trying to quantify this number.
- Finds that the D-state correction is signifcant at large W. The x-dependent
correction differs from the (traditional) constant correction only for 1st
W point.
- Shows a plot of g1n,g2n with new binning, compared to world data.
- Writing a report on neutron extraction.
- Frank: "what remains to complete the neutron analysis?". Shige wants to recheck all
codes, and quantify the F1,F2 error estimate.
- Oscar will check the sytematics as he did for proton.
- Mark has done some checks of the deuteron radiative correction model dependence. He'll
summarize.
- Mark
- Our g1d is consistent with the EG1b data. Mark notes that A1d is essentially
independent of Q2
(within the error bands of the Eg1b data) for the Q2 range relevent
to the RSS radiative corrections.
- Points out that for the deuteron, all available models are quite poor. It's not
reasonable to use them to evaluate the RC systematic. Oscar suggests that
Mark instead quantify the effect on the RCs of using different functional forms
for the deuteron fit. The variation of the additive term Arc is what is relevent.
- Peter's code is posted on his webpage.
- Oscar
- Requests Frank update his deuteron SUMMARY files.
- Oscar recently reread Wally's PRC and Zein-Eddine's higher twist PRL, along with Dong's new
paper. a2 matrix element (3rd moment) should represent TMC term, but this is not
what he finds when he tests with the PDFs. He is in discussion with Wally about
this
- Karl
- Performed study of proton g1 higher moments.
- Ratio of PDF/RSS becomes larger for each successive higher moment.
04/16/07
Present : Mark, Shige, Oscar (phone), Karl
- Shige
- Applied the Melnitchouk et al x-dependent D-state correction. Found very little
effect except for highest x point which changed by about 10%.
- Shows plots of g1n,g2n. They are consistent with world data. Also consistent
with zero over most of x range.
- Shige will test some other bin sizes and post tables of his results on the web.
- Oscar requests a short writeup describing the fits that Shige used so we can
proceed with the integrals: table of smeared proton results and final neutron,
along with code to get A1n, A2n.
- Shige is using F1n,F2n from Peter's code F1F2IN06.F. It's not clear whether they
are free or smeared. Shige will discuss with Peter.
- Oscar suggests Shige should go directly from g1n,g2n to A1n,A2n.
- All
- Mark discusses new target mass corrections paper from Dong.
- Oscar reread the earlier Dong TMC prl regarding the application of
TMCs to the twist-2 part of g2.
He concludes that since we get g2ww from our data, we don't need to apply
TMCs to our g2ww, they are already in by definition.
- Mark raises the issue of using nachtman variable for d2 as recommended by Dong.
Not clear whether we should do this.
- Oscar points out that we need sum rules for the Deuteron/Neutron, then we
are done RSS.
- To estimate the DIS contribution to Gamma_2, Karl uses g1(resonance) to form g2ww.
Oscar requests Karl to look at 4th and 6th moments of ratio of PDF/Data to
estimate the contribution of higher twist in our resonance g1.
Significant high twist contributions would show as
increasing relative differences between our fit and the pdf's with
increasing moment. Oscar points out that this is discussed in A. Deur's Bjorken
sum rule paper.
- Oscar mentions that we might want to extract f2, and polarizabilities from RSS data.
- Oscar will be at JLab next Thursday.
04/10/07
Present : Mark, Shige, Oscar (phone), Frank, Karl
- Karl
- Updated moments note to discuss Gamma_2, and the uncertainty of DIS contribution.
- Oscar suggests that it may not be valid to extend the Regge fits into the
resonance region for "Scenario III". Also, believes that NLO-2 versions of
the pdfs can be assumed to be independent of NLO-1 versions.
- Oscar suggests several possibilities to evaluate the uncertainty of the DIS contribution.
- Karl shows comparison of data to chiral soliton models.
- Group reviews and critiques Karl's talk for DIS07.
- Shige
- Sees interesting structure in neutron g1,g2. Mark remarks that it probably
arises from the F2D that Shige is using to form the structure functions.
- Mark suggests that Shige should not mix fits and data when extracting
the neutron.
- Shige raises the issue of how to treat the A2 fit error propagation. Presently,
Mark fits the entire resonance region A2 to a constant with an error given
by the sigma/sqrt(N). Does this mean that we must treat the entire resonace
region as a single bin?
- After lengthy discussion, conclusion appears to be that if we use the fit
we are indeed left with a single bin for the resonance region. Oscar suggests
that Shige should perform the deuteron-proton subtraction using data, not fits.
On the other hand, the fit should be used for integrations.
- Shige shows size of the D-state correction in the structure functions: Not
very significant for x>0.7.
- Mark used Peter's R for radiative corrections, not R1998. He requests that
Shige should doublecheck which F2,R he is using to create his g1d fit.
- Oscar
- Discusses the D-state correction. He remarks that the correction, in fact, has
an x-dependence. It is not constant. This topic is treated in a paper
by W. Melnitchouk et al: PLB 346, 165 (1995).
- Oscar digitized the correction using WINDIG (windows digitizer) and created
a text file which Shige can use to compare to the 'standard' prescription.
Mark notes that the correction is apparently independent of Q2.
04/02/07
Present : Mark, Oscar (phone), Shige, Karl
- Shige
- Improved his calculation of g1,g2 statistical error. Previously he evaluated
the error by simultaneously varying A1 and A2 by their respective errors dA1 and dA2.
- Now he adds the errors in quadrature: ( d(g1)/dA1 )^2 dA1^2 + ( d(g1)/dA2 )^2 dA2^2.
- The error is reduced by a factor of approximately 0.7. Oscar notes that this
latest error is similar in magnitude to Shige original attempt which came from
propagating the relative error of rebinned data through the smearing.
- Shige is using version 6c of the fit for his work.
- Oscar suggests that we discuss the sytematic effect of using other fits in
a long paper.
- Mark
- For the deuteron radiative corrections, he suppresses the R2 (~1350 MeV) resonance.
The three Delta resonance parameters are allowed to vary. For R3, and R4, he allows
the amplitude to vary, but fixes the centroid and width to the proton fit values.
- For the DIS part he is using the V6c fit : DIS ~ (b_0 + b_1x + b_2x^2 + b_3x^3)x^alpha, allowing only the alpha parameter to vary. The remaining parameters are fixed to the
proton fit values.
- Mark also tested the V622 DIS fit : DIS ~ b_0x^alpha. Both look reasonable, but the
V6c seems to reproduce the data better. Mark will post the chi2/N.
- Mark is using 15 MeV binned data for the fitting.
- Karl notes that the fit produces a tiny error near threshold, which is not
representative of the data.
- Oscar believes this is due to having a single (hence well defined) free parameter
in the DIS.
- Mark notes that the DIS fit is dominated by the more precise data at larger W.
- Discussion follows. Perhaps we need to include a systematic error in our fit
uncertainty due to the effect of various functional forms. Oscar suggest to
take the variance of several different fit forms as the systematic error.
- Karl
- Evaluated two new DIS fit forms DIS ~ b_0x^alpha, and DIS ~ (b_0+b_1x)x^alpha.
- Both give excellent reduced chi-squared.
- The parameters of the first form have smaller errors, which is consistent
with Karl's earlier study that found that only one or two parameters are
needed to satisfactorially reproduce the DIS background.
- Oscar notes some oddities in Karl's spreadsheet and asks for clarification.
Karl promises to look into it quickly.
- Also working on DIS07 talk. He will circulate a version for next monday's meeting.
03/26/07
Present : Oscar (phone), Mark, Shige, Karl
- General discussion
- Shige notes that the RSS work disk is almost full. Mark will try to
find some space for the SANE/GEP files that are currently being stored there.
- Shige
- Still having some difficulty with the fitting routine. He tightened the
convergence criteria and found that the error matrix elements go to zero.
- Shows g1p smeared with new errors which come from the A1,A2 fit.
- Shige believes the resulting error may be too big.
- Mark suggest that Shige use ( d(g1p smeared)/dA1 )^2 dA1^2 + ( d(g1p smeared)/dA2 )^2 dA2^2. The necessary derivatives can be calculated numerically. This method assumes no
correlation between A1 and A2.
- Shige discusses the effect of rebinning on the errors. Mark points out that we now
have a fit with continous error band so rebinning should have no effect.
- Mark points out that we should use a fit to deuteron when we subtract out the
proton fit. Presently, Shige subtracts the proton fit from the deuteron data to
get neutron.
- Oscar notes that the fit integrals should conserve the data relative statistical
error, as we do with d2.
- Shige is working on systematic error study for deuteron.
- Shige is leaving at the end of April, but will continue working on RSS.
- Mark
- Found that the new nitrogen asymmetry correction has negligible effect on the
deuteron radiative corrections.
- Karl
- Studying the DIS fit to A1,A2, by evaluating several different functional forms
to see which parameters are significant.
- Oscar suggests Karl add two further forms to his study : DIS ~ b_1 x^alpha and
DIS ~ (b_0 + b_1 x) x^alpha.
- Karl will send these results to Oscar.
- Karl has talk at DIS07 around April 18th. Mark suggests to try to finish
this week.
03/19/07
Present : Mark, Oscar (phone), Shige, Frank, Karl
- Mark
- Redid the Deuteron RCs with new Nitrogen asymmetry correction.
- Made some adjustments to T_in, T_out thicknesses. Did not see
any significant change.
- Mark is trying to decide how to implement the new changes in the Quasielastic.
He notes that PWIA does not reproduce the Deuteron Quasielastic
very well.
- Peter has been working on this issue for CLAS.
- Mark must leave early since he is Run Coordinator this week.
- Shige
- Catching up on the RSS emails sent while he was away.
- Having some difficulty with the fitting routine : Matrix elements don't converge.
- Oscar
- Asks Frank what causes the asymmetry to be set to zero below the pion threshold
in the RSS_SUMMARY files.
- Frank will check it out.
- Mark will post latest Nitrogen asymmetry correction files with values below
the pion threshold.
- Discusses evolution of data to constant Q2.
- Comes to the conclusion that the systematic error is conservative.
- It appears that we are basically assuming A1 is independent of Q2.
The Q2-dependence comes mainly from the F1 fit.
- Karl
- Oscar noticed that errors on the DIS fit parameters were huge in pass VIb.
- Karl: seems to be an issue with the RC iterative procedure. Ran pass VIc
radiative corrections, this time truncating the iteration at 5, instead
of 11.
- Very little effect on the RCs, but the fit parameters have more reasonable errors.
- Karl suspected that this is due to using too many fit parameters (5) to describe
the DIS background.
- Evaluated 5 different DIS forms for goodness of fit
- no background
- constant
- linear
- quadratic
- cubic
- cubic*x^alpha
- All forms gave reasonable chi2/N. Best Chi2/N comes from assuming the DIS is a constant.
From this Karl concludes that the current DIS parameters don't hold much significance.
- Oscar suggests Karl test the forms :A1~x^a, and A1~b x^a, A1~ (b0 + b1x)x^a, which
are more justified.
- Oscar also notes that a fit to sig_TT, sig_LT could use the RSS dis Regge fit.
- Frank
- Regarding the compression of x-range caused by evolving to constant Q2: Asks Oscar
whether crossover of the original/final curve is significant.
- Oscar states that it is purely kinematical.
03/12/07
Present : Mark, Oscar (phone), Frank, Karl
- Karl
- Performed new pass of radiative corrections (VIb) to include
the new Nitrogen Asymmetry correction advocated by Oscar.
(New Nitrogen asymmetry correction uses radiated, acceptance averaged
cross sections
instead of born xs.)
- Only significant difference (to the data) from pass VIa is just at threshold.
- Oscar points out that the DIS portion of the A1,A2 fit has changed. Asks Karl
to investigate.
- Oscar
- Reran the duality integrals.
- Found small differences with previous version.
- Oscar asks Karl to review the RC systematic method we used last year.
He requests Karl to send updated model file to evaluate the systematic.
- All
- It is agreed we will attempt to update the prl plots and tables
before publication.
03/05/07
Present : Mark, Karl, Oscar (phone), Shige, Frank
- Shige:
- Working to include DIS and elastic contributions into his smearing technique.
- He uses Oscar's Regge fit for DIS, and the standard formulation for elastic in terms of form factors.
- For g2, he assumes g2WW, with g1 in the resonance region given by the Regge fit.
Karl notes that there is significant difference in g2ww depending on which g1
is used in the resonance region.
- Shige finds that the contribution from elastic and DIS are very small: 0.001 absolute
maximum contribution to g1 and g2. He plans to recheck his analysis.
- Regarding the error matrix, Shige still finds some differences with Karl's tables.
They will meet to discuss.
- Shige will be away next week.
- Karl:
- Updating his moments technote to include Gamma_2.
- Discusses g2WW estimate of DIS contribution to Gamma_2. g2WW depends on which
g1 model is chosen. He uses the RSS fit in the resonance region, and has
checked the effect of using various DIS g1 models in the unmeasured region.
He finds a maximum variation of 10% in g2WW depending on which DIS g1 he chooses.
- Oscar requests that Karl also quantify the effect of using other models (instead
of the RSS fit) in the resonance region.
- Karl discusses the elastic contribution to Gamma_2. He is using the Mergell et al
Form Factors (from 1995), and assuming 5% error on this contribution to the BC
sum rule.
- Mark points out that 5% is probably an overestimate, and that 3% may be more
reasonable.
- Mark will also forward the most recent FF parameterization, that he used for
the RSS elastic analysis.
- Frank:
- Mark inquires about PRL status.
- Frank: the PRL has received "editorial acceptance", but there may still be some
space issues.
- Frank will wait till this is clarified before informing the collaboration.
- Oscar:
- Has an improved Nitrogen correction for protons,
which has the advantage that it does not diverge at the pion threshold.
- Oscar points out that the Nitrogen correction should utilize radiated,
acceptance-averaged cross sections, not Born cross sections.
- The main difference from the previous results is in the first few
W bins (plot).
- Since we discard the first bin and quote a very large error on the remaining
points around threshold, there should be little impact on the results. However,
we will need to verify.
- Oscar emphasizes that any formulation of g2WW should not include an elastic
contribution. As pointed out by Wally Melnitchouk, g2WW is twist-2 and therefore
can not include elastic.
02/12/07
Present : Mark, Shige, Oscar, Karl
- Shige:
- Working on propogation of A1,A2 fit parameter errors. He is having problems
reproducing the official error matrix.
- Will continue his debugging.
- Oscar:
- Working on DIS fit for g1p,g1n.
- Neutron fit uses E143 (neutron) and E155 (D-P).
- Oscar notes the big correlation between the exponent parameter and the higher twist (Q2) coeficient.
- Suggests that we use his fit down to x=0.1 and then use E154 value down to zero.
- Will try to include Hermes and E154 data in his fit.
- Karl:
- Working on moments.
- Has set up a new summary page.
- Compares Bianchi and Thomas DIS fits (p and n) to Oscar's fits.
- Notes that Bianchi and Thomas DIS fit does not include E155. We should
contact the authors to see if they have an updated fit.
- Oscar suggests we look at Frank's E155 g1/F1 fit.
- Oscar requests that Karl send him Bianchi and Thomas DIS neutron table. He will
make global comparison slide.
- Oscar points out that Karl's neutron Gamma_1 slide is using data, not a fit.
Also, it is the integral of smeared neutron, not unsmeared.
- Shige suggests we compare integral of smeared/unsmeared proton fit to see
the effect on the integral.
- Mark:
- Notes that there will be a plenary Spin talk in Munich. We need to consider
which slide(s) to provide the speaker for RSS and SANE.
02/19/07
No meeting. President's day.
02/12/07
Present : Mark, Shige, Oscar(phone), Karl
- Frank:
- Sent prl back to editors on Friday before he could implement
Mark's comments.
- Frank will not go to April APS. Missed the deadline.
- Oscar mentions that James Maxwell can present some RSS
slides at APS during his SANE talk.
- Mark:
- Completed Deuteron RC with Arenhovel's new calculations.
- Mark shows the Q.E. asymmetry model curves which are large at
large W. Points out that these large values are suppressed by
f_rc.
- Mark shows f_rc and A_rc, which are very flat beyond the Delta
(==> so will not change data shape very much).
- Discusses the structure of his data file. Karl requests
unimplemented entries like sigma_LT be set to some obvious value (like
zero or -1E6)
- Mark is using Shige's latest Dilution factors. He found a
non-negligible difference of about 10% near threshold and elsewhere
from the old DFs.
- Shows fit he is using for A1 in R.C. For A2 he uses a
constant: the weighted average.
- Most A1 fit parameters seem significant.
- Only one iteration needed in radiative corrections.
- Karl can use these fits for the Q2 evolution of Deuteron.
- Karl:
- Working to organize the moments work. Asks what topics
will be in paper.
- Mark : Proton, Deuteron and Neutron moments should be in
prl. Neutron extraction and full neutron results should go in
Shige's archival paper.
- Oscar : include plots only when we can compare to existing data
: Hall A for neutron, Hall B for proton, etc.
- Oscar:
- Discusses neutron smearing.
- Oscar made a fit to E143 and E155 g1p data (1<Q2<1.5) for
low x (plot
1 plot
2).
- Suggests that we compare Bianchi and Thomas prediction to this
3 parameter fit.
- Shige can use the SLAC W>2 GeV data to constrain his error
propagation through the smearing.
- Oscar points out that g2WW at low x agrees well with our g2
data as shown in Frank's prl. So as long as we use a reasonable
g1 fit, g2ww should be good at low x.
- Oscar and Mark point out that the range of EG1 Gamma_1 integral
has to be checked. First they don't have same resonance region
range. Second, their "total" integral actually includes data that
they measured above W=2GeV. Karl promises to look into this.
- Regarding ELT sum rule: Oscar states that we can not get ELT
directly from the proton and deuteron integrals. The x-dependence
is not the same for proton and deuteron. We really need g1n(x)
and g2n(x). Might be best to work from fits to the data.
- Oscar points out that ELT is an exact sum rule, and that the
sea contribution cancels. Left only with valence.
- Shige:
- Working on the propagation of statistical error through the
smearing.
- Shige made a fit to the stat error of A1 and A2. From
this he can predict error at any x.
- Using this fit he propagated A1+-dA1 and A2+-dA2 through the
smearing. He finds huge error at low x which he doesn't think is
reasonable.
- Extensive discussion follows.
- Mark points out that the A1,A2 fit has errors on the parameters
which reflect the statistical uncertainty of the data. In light
of this, we probably should not propagate the error point by point. He
suggests that Shige could randomly vary each fit parameter
simultaneously over a Gaussian distribution with a sigma the size of
each error bar. Then evaluate the resulting Gaussian sigma of the
fit at each W-point.
02/05/07
- Oscar
- Oscar discusses the differing formulations of d2. ie, how to
get from the (g2-g2ww) form to the expression using g1 and g2.
- Frank
- Going to Florida in April. Will not be able to go to
DIS07(April 16) in Munich.
- Discussion of who can go instead.
- Oscar: Need answer for Rolf this afternoon.
- Frank expects to send latest version of the PRL this week.
Not totally certain how to address all comments yet.
- Regarding the referee's request to include some standard
equations (A1, A2, etc) it is decided to reference the E143 paper
instead.
- Mark
- Included the new Arenhovel QE results in his radcor code.
- The new grid covers 3755 < E0 < 5755 and the full range
of W.
- He started running today and expects results tomorrow.
- Mark will also include Shige's latest Dilution factors.
- Next step is to evaluate the Deuteron systematic.
- P_b : uncertainty will probably be same as in the proton
paper.
- P_t : we have more TE's but the error is slightly larger.
- Mark mentions that the structure of his deuteron radcor files
is slightly different from the proton files.
- Mark points out that none of the available deuteron models do
a very good job reproducing the data. It may be best to vary the RSS
model over some reasonable range and use this to evaluate the RC model
dependence.
- Shige
- Regarding the deuteron dilution factor systematic, Shige will
discuss with Peter.
- Neutron systematics will be even harder to evaluate.
- Shige is also trying to properly propogate the statistical
error through the smearing. It's not clear how to address the very
large statistical uncertainties at low and high W.
- Frank points out that the neutron results will have
systematic contribution from proton, neutron and also the extraction
itself.
- Karl
- Evaluated the Q2 evolution of deuteron and neutron g1
structure function and moments by assuming g1/F1 is independent of Q2.
- Oscar prefers that we use functional form of A1D and A2D as
we did for proton.
- Mark thinks he turned off DIS Q2 contribution in his fit,
will double check.
01/29/07
PAC31 week :No meeting
01/16/07
- All
- Review of last few meetings. Shige summarizes the details.
- Karl:
- Regarding quark polarizations: Following Oscar's suggestion
to form delta u/u and delta d/d for W>1.77 GeV Q2>1 RSS data.
- Shows latest result. They don't seem correct. Mark suggests
that Karl should use "per-nucleon" values for the deuteron structure
functions.
- Karl has formed neutron Gamma_1, Gamma_2, and d2 from Shiges
tables of smeared neutron RSS structure functions. Shows comparison to
Hall A E94010 neutron results at slightly lower Q2.
- Karl has not yet evolved the RSS data to constant Q2, and the
W coverage is not the same for the two experiments. Nevertheless, the
data seem to match up reasonably. He will make the needed corrections.
- Oscar requests that DIS,elastic, etc. contributions be
included so we can evaluate the full sum rules. For DIS, fit the lowest
x data and then extrapolate to x=0 (Regge form is probably best).
- Regarding Q2 dependence: Mark states that his fit of deuteron
A1 contains no Q2 dependence. He removed it because it seemed to give
unreasonable results. Peter suggests we assume g1/F1 is constant and
get Q2 dependence solely from F1. He points out that there is a plot in
his latest proposal
showing g1/F1 for all world data that demonstrates the relative
Q2-independence for W>1.8, Q2>1.
- Karl also tried to extract the neutron moments from g1p, g1d
using only D-state correction. Did not get reasonable results, which
was surprising, given that nucl-th/9709015
claims this to be good to 3%. Will repeat more carefully.
- Points out nice webpage
of deuteron and proton data. Peter warns that some of this data may be
incorrect. The page was set up by a summer student and may not be up to
date.
- Shige:
- Shows plot of RSS g1n compared to hall A data.
- All : discussion of quark polarizations and "per-nucleon"
issue.
- Peter points out that his code F1F2IN06 provides per-nucleon
results.
- Oscar notes that the RSS data at large W used for the quark
polarizations satisfies Q2>1.15, so we have similar constraints to
Hall B results.
- Shige is working on his Hall C talk. Will send out something to
the group to review shortly.
- Mark:
- Notes that deadline is approaching fast for several
conferences: INPP 2007 in Tokyo, Japan, Pan Pacific High Energy
conference in Vancouver (August), and Baryons 07.
- Peter will probably go to Pan Pacific. Karl is considering
Baryons 07.
- Mark is writing new code to interpolate the latest Arenhovel
tables. He will then run them through the R.C. code again and post the
new results. Does not expect large change.
- Notes that Frank has not received any response from the
referees yet.
- We will resume regular meetings next monday.
01/08/07
- Shige:
- Checking to see if his smearing method agrees with Peter's
code.
- Peter first looks at the momentum distribution functions. He
splits the range 0 to 1 into 20 evenly spaced bins, each with equal
probability.
- Shige is modifying Peter's code so that it will also provide
cross sections. Then he can perform a direct comparison.
- Regarding the Hall C talk on Jan. 25th, Shige has about 15
slides already prepared.
- Mark and Frank suggest that Shige probably does not need to
show the asymmetries.
- Karl will send the sum rule/moment xmgrace files to Shige.
- Peter mentions it would be nice to compare our d2n to hall A's
result.
- Karl will form d2n from our data if Shige wants to show it in
his talk.
- Peter can add RSS to the hall B duality plots. He will make
some plots for Shige.
- Mark will send the relevent tables to Peter (g1p & g1d vs x
at constant Q2).
- Peter suggests that we assume g1/F1 is constant and then assign
all the Q2 dependence to F1.
- Peter is using code F1F2IN06 for smearing.
- Peter points out that John Arrington found some problems with
Eric's proton fit. The problem arises when W2>4GeV2. They hope to
include some of Nadia Fomin's data to improve the fit, or maybe just
generalize to make a smooth transition to NMC or other DIS fit.
- Karl:
- Karl discusses his results for Delta u/u and Delta d/d.
- Needs to double check Delta d/d result.
- Discussion of sum rules paper: Karl has limited time due to
PAC, but promises to try to finalize.
- Hall B is also working on a sum rules paper for EG1b, so time
is tight.
- Peter points out that since we published g1p & g2p plots,
it is fair game for anyone else to form the moments (and publish
without us).
- Last major topic to finalize is how to properly include the DIS
contribution.
- (Peter points out that he has 'machinery' for fitting world F1d
data. May be useful to form world g1d fit.)
- Peter suggests that Karl use LSS06 for DIS contribution of
moments. This fit is very new (Dec. 2006). Other possibilities would be
AAC or Bianchi and Thomas (II).
- Peter suggest that Karl contact Stamenov for LSS function that
directly returns g1.
- We should also form Bjorken sum rule. Peter points out that
Bjorken is especially sensitive to DIS since the Delta contribution is
minimized.
- Mark:
- Received Arenhovel's calculation for quasi-free deuteron over
wider range than previous table. This will change the radiative
corrections somewhat.
- Mark will post new version on his website when completed.
- Short discussion of whether the calculation is reasonable at
high x.
- Peter points out that it's possible to gain information on the
deuteron wavefunction from high-x deuteron data (especially EG4 data).
The counts are very limited in this region so fits/calculations should
not really be trusted for now.
- Mark mentions that the deadline is approaching for Baryons 07
in Seoul Korea, June 11-15. Shige does not think he wants to go. Karl
may submit an abstract. Deadline is in February? Peter mentions small
workshop in Trento (15 people) at the same time as Baryon07. Mark
mentions that the deadline for April APS in Jacksonville is quickly
approaching.
- No meeting on Monday due to holiday.
12/11/06
- Mark Oscar and Shige present
- Karl not present. (Thanks to Shige for recap of the meeting.)
- Oscar briefly talked about a recent seminar given at UVa by
Igor
Strakovsky who discussed the resonance at ~1355MeV (see Oscar's email
on Dec 11).
- Shige: talked about the new deuteron DFs which were posted on
his webpage.
- Mark discussed the RC. He will get new deuteron asym results
using the new DFs.
11/27/06
- Shige
- Comparing RSS deuteron model to Peter's model.
- Redid PF study: Data/model comparison repeated. There is not
much change.
- May ask Peter to repeat his fit using version of R that is
consistent with the rest of our analysis. But, this will probably have
very little effect.
- Oscar: We should just use Peter's current model (without
changing R). The model looked excellent compared to other data and
looks reasonable with our data. The only major difference is R
subroutine and this has really small effect.
- Shige will proceed with DF calculations using Peter's model.
- All : disussion of anomolous point in Deuteron A_perp at
around W=1300 MeV. It looks quite strange in A2 (sign flip). Mark will
make some plots from Frank's tables to check systematics. Mark will
also look at raw asymmetries to see if the anomoly is present in the
raw data, or is a result of one of the corrections.
- Mark
- Compared our deuteron data to EG1B deuteron and to the hall B
models.
- A2 models do much better than the A1 models.
- Karl offers to send Mark the Hall B RC table.
- Mark will begin systematic study of the model dependence.
- The A1 model dependence is atleast the size of the stat
error, or even worse, but the models are quite bad, so this may not be
the best way to evaluate.
- Can we compare Hall B proton + Hall A neutron with our
deuteron? No, Hall A neutron is not yet available at our Q2.
- Arenhovel sent Mark a new calculation of deuteron QE with
larger grid in E,E', and W.
- Frank
- All : Discussion of the paper.
11/13/06
- Frank:
- Next week he will probably be ready to send new draft to the
collaboration. Not ready yet. Maybe the monday after Thanksgiving.
- Shige:
- Tried Peter's model with RSS ressf.f
- He is checking different versions of deuteron xs fits to see
if it's worth to repeat the dilution factor/packing fraction
calculation.
- The biggest difference seems to be a low W (around the
Delta), not much difference at large W.
- Peter is using an old version (March) of Eric Christy's code.
- Conclusion: If we use Peter's code (which agrees well with
data) then we should use it with our version of Christy fit.
- Shige also varied pion value in the Christy code: found that
it had not much effect.
- Shige believes that Peter's model is probably better, but we
need to ask Peter to repeat with July 2005 Christy routine, which would
be consistent with our analysis.
- Whatever we do, we should use same model consistently
throughout analysis.
- Mark:
- Working on Deuteron R.C.
- Oscar requests the error matrix.
- The current file has some incorrect leftovers (?).
- Using 45 MeV bins.
- Mark is treating A2 as a constant.
- He sees an anomaly at x=0.65.
- Starting to look at the systematics, he will create a short
write-up when complete.
- Will produce results in 15 MeV bins so others can rebin to
whatever they like.
- Mark has requested a larger spread (in energy) in the Q.E.
calculation from Arenhovel.
- Karl expresses some concern regarding the (small) size of the
deuteron radiative corrections relative to what he found with the
proton. Mark points out that the deuteron spectra has much less
structure which would lead to smaller corrections. Karl notes that we
could compare the new code to Eg1 deuteron radiative correction tables.
11/08/06
- No meeting
11/01/06
- All
- Discussion of latest PRL draft.
- Frank recieved comments from Oscar and Shige (local
duality=Bloom-Gilman).
- Shige
- Regarding dilution factor: using the current model of
deuteron in the M.C. instead of Peter's model results in the Packing
Fraction increasing by 2-3%.
- The comparison of data to MC is slightly better at lower W
for Peter's model.
- However, "our" model is better for perpendicular comparison.
- Oscar compared the models to data in Donal's database
from NE11.
- His conclusion is that there is just no good model for
Deuteron Q.E. All available codes have some problem. He has not yet
tried Peter's code, but will try shortly.
- Shige is also calculating g1d, g2d. Not sure which R to use.
Proton R from Eric's code?
- Mark
- Working on Deuteron R.C.
- New webpage
where he will post all results.
- Arenhovel's cross section in the Q.E. region is much smaller
than either Hall C code or y-scaling result.
- The comparison with asymmetry is reasonable though.
- Mark shows A1, A2 with Q.E. tail subtracted. He finds a weird
point in A2 around the Delta region.
- Mark has started to fit A1 using the Oscar/Stein Breit-Wigner
form.
- We will meet two weeks from today. No meeting next week.
10/??/06
- Oscar:
- New Dong paper not yet on Spires
- Simula fits and Bianchi and Thomas fits did not incorporate the
E155 (and newer) data.
- They use only E143 and before, such as Q2=0 Bonn/Mainz sigma_LT
sigma_TT data.
- This is why they are featureless in the resonance region. For
this reason, Oscar is reluctant to use them.
- Oscar requests a comparison of E143 and E155 data to the fits.
- Karl should send his Bianchi Thomas fit to Oscar.
- The only existing g2 fit seems to be to Hermes data.
- Shige:
- Working on Peter's routine for smearing: creating a table of
Fermi momentums.
- Regarding comparison of data to the M.C. : Old comparison
looked better (both for proton and Deuteron).
- Using same proton (Eric) model. What else changed? C, He and
Nitrogen were adjusted in QFS in order to agree with hall B.
- Previously: we made modifications to QFS scaling factor. Now,
Shige uses scale=1.0.
- Mark:
- Working on Deuteron R.C.
- Slowly modifying the code.
- Will discuss with Arenhovel to get quasi-free deuteron
calculation.
- Oscar want's to know if Mark will treat Q.E. tail similarly to
how Karl treated proton elastic.
- Mark: can do both methods, i.e. as tail subtraction with
associated f_rc +A_rc, and also simply as another inelastic channel.
- Oscar would like to have f_rc in order to properly handle
statistical error.
- Frank:
- Frank is working on PRL comments.
10/09/06
- Frank:
- Received new comments from Shige on the PRL.
- Oscar:
- Converted the Hermes A1 data to g1: Over a huge range in Q2
they still have really large error, and agree with RSS.
- Also found that Hermes is not covering the entire range of
W. The resonance coverage is 1.3<W<1.8 GeV.
- Each Q2 point only has local W coverage. Need to average
over all the Q2 points in order to cover the full resonance region.
- For these reasons Oscar is reluctant to devote much space in
our prl discussing the Hermes data, as requested by the referee.
- Oscar then discussed the recent paper of Y.B.
Dong(Nucl.Phys.A744:293-306,2004). Apparently the paper compares
g1&g2 parameterizations with pdfs, so it's not clear if it is so
meaningful. But the paper also claims that the Wandzura-Wilczek
sum run does not need to be corrected for TMCs. This directly
impacts how we handle the DIS contribution to the Gamma_2 moment.
- Oscar then points out that Dong uses the nachtmann variable for
his integrals, which had been strongly discouraged previously by the
Hall C group. It appears no one is really certain whether the
nachtmann variable is appropriate or not.
- The paper claims onset of duality should be at about 1.7-2.0
GeV2.
- Oscar also briefly discusses a new paper by Fernando Stephens
and Wally Melnitchouk.
- General Discussion of PRL comments
- Oscar notes that it is not rigorous to use g1,g2 and x_bjorken
at our kinematics. We should really use G1,G2 and W. May
need to add a brief sentence explaining that we are examining
transition from DIS to resonance.
- Frank is still not sure how to reduce the jargon in the first
paragraph.
- Frank raises the issue of whether the OPE is applicable at low
Q2 if you just include more and more terms. Not clear, we should
talk to Wally.
09/30/06
- Mark:
- Does not think new changes to the PRL will be enough for the
referees.
- Shige:
- Working on smearing effect.
- Peter:
- Has some useful codes for that. Can provide a grid (200
bins) of probability of finding momentum pz, p^2 .
- Then for any given (nu,Q2) can calculate the distribution using
minuit for a free proton and free neutron structure function.
- Comparison to the existing deuteron data provides neutron
parameters since the proton parameters are fixed using Eric's code
.
- Peter breaks the entire region into 20 bins, and assumes each
bin has 5% probability.
- Peter also modified Eric's RESMOD routine by hard-wiring all
the variable parameters. This provides a factor of 10 improvement in
speed.
- Notes that there is no way to properly smear proton and neutron
near threhold which properly takes breakup into account.
- Peter is using Laget's code for breakup, but needs to somehow
account for 2-body currents etc.
- Oscar: comments that Peter is building a "real" model of the
deuteron. We may only need a phenomenological fit.
- Oscar:
- Using our free proton fit and "something" for the neutron, can
iterate till we converge to the deuteron data. Some of the resulting
neutron parameters may be insignificant, but this will be revealed by
the fit errors.
- Peter believes it is incorrect to use arbitrary mass and widths
for the resonances. We could fix them using SAID, for
example. Notes that what we really are trying to determine is the
Q2-dependence of the form factors. The helicity amplitudes should
not change with Q2. Inclusive scattering unfortunately does not give
much information except to constrain the overall form.
- Oscar states that our main goal should be to perform a
reasonable subtraction of the proton to get the neutron
x-dependence. This is important for d2n and moments.
- Peter notes that in EG1b they found that duality seems to work
better for deuteron than proton. Also, neutron does not appear to
work as well as proton.
- Oscar et. al : Discussion of problem of extracting neutron in
resonance region for Deuteron as well as He3. Karl notes that
Hall A never extracted resonance region neutron spin structure
functions, only moments.
- Peter notes that the P+N final state in EG4 can really get
neutron information.
- Oscar reiterates that he prefers to integrate a fit to the
data, (instead of the data itself), for the moments.
- Peter can produce sigma_3/2 and sigma_1/2 in Laget's code which
Mark could use for the radiative corrections. The results will in
effect cover the region 0<Q2<10 GeV2 and 0<W<3.2 GeV.
Peter also has table covering Q2<0.4 GeV2 from
Arenhovel. Mark has similar table at Q2=1.3 GeV2.
- Oscar notes that we should compare the old (hallC) deuteron
model to Peter's new results. This would tell us if its
worthwhile to redo the packing fraction and dilution factor. Peter
believes there will be a significant effect only below the delta
resonance. Mayber 10% elsewhere.
- Oscar would like to see how well the models reproduce our data
(See June 14th
yield plots on Shige's
webpage). Also, we need to update a few portions of our fit.
- Peter's model uses Donal's y-scaling in
quasi-elastic. Using a smeared R from Eric's fit, and
assuming smeared neutron R = smeared proton R.
- Peter will send the code to Mark for the M.C.
- Oscar may be here for next weeks meeting.
- Mark:
- Recieved some tables from Arenhovel. Peter comments that
Laget believes Arenhovel's code is more reliable near threshold, but
this is probably not significant at RSS kinematics.
- Mark shows a comparison of Arenhovel's Apar and Aper to our
data : There is 'rough' agreement which seems to indicate sizable
contamination from the Delta on large W side of the Quasi-elastic and
dip region.
- Oscar points out that Stein directly subtracted a Q.E. tail
from the data for radiative corrections. Karl mentions that Hall
A treated Q.E. as just another inelastic resonance.
- Peter : our subtraction will be model-dependent, but the models
will improve over the next few years.
- Mark will ask Arenhovel for wider W-coverage.
- Arenhovel is using the Walcher form factor which is better than
Galster at our Q2.
- Peter uses a different form factor fit for the polarized and
unpolarized calculations. It's not obvious how to handle this
properly.
09/18/06
- Mark:
- Talked with Peter RE new model he is working on for Eg4
to fit all Deuteron data.
- Iona's model/data has problem at threshold (for W<1.3).
- We may be able to use this new model for P.F. etc.
- Oscar: Shige found quite high P.F. for deuteron compared to
NH3. Perhaps this will help there.
- Karl:
- Shows moments plots.
- Oscar points out that not all the SLAC data is shown. They did
not concentrate much on the 16 GeV and 9GeV data, mostly focused on the
27 GeV data instead.
- But the SLAC dilution factor may be bad. They used F2
from NMC and R1990 which is not great at our W.
- Also, there were no good models of g2 at the time.
- We need to find out how well Eric's fit joins to DIS.
- Oscar will look at what a pure data DIS contribution to Gamma_1
would look like.
- Karl : shows Gamma_2. For DIS contribution, he tested what the
Stratmann Bag-model would give, compared to g2WW, and Weigel's chiral
soliton.
- Oscar points out that we probably need to apply TMCs to the
models (Stratmann's g2ww atleast).
- Shige:
- Now using R1998 (from Mark)
- Shows plot comparing R1990 and R1998. There is about 15%
difference, which looks like a "resonance".
- In fact, this has <1% effect on the smeared A1 and A2..
- Shige is not sure which kinematic variables to use for the
neutron. The Deuteron and Proton values differ by about 5% below
W=1.25.
- Above W=1.25 they agree within 1%.
- Frank suggests he take the statistics weighted average.
- Oscar:
- Working on DIS contribution to moments for next week.
09/11/06
- Shige:
- Shows plot of neutron smeared cross section, along with Apar
& Aperp, and A1 & A2.
- Using 30 MeV bins, does not see much structure.
- With 60 MeV bins has nice plot. Both A1 and A2 are
negative on average.
- Probably won't have to unsmear since he is using 60 MeV bin.
- Karl:
- Shows plots of the moments
- Mark points out Karl is using old Soffer-Teryaev curve.
- Oscar : it would be interesting to quantify the comparison of
PDF's to the E143 DIS data. Could use this
to determine how much of DIS "leaks" into Resonance and vice versa.
- Mark:
- Frank:
- Regarding the PRL referees comments : it will be difficult to
satisfactorily cover both duality and g2 in the paper.
- Believes it is best to remove duality table from paper.
Oscar agrees. Can use extra space to discuss that 50% of our d2
comes from twist-2.
- Oscar: we should really use G1,G2 instead of g1,g2. We
need to add discussion about Hermes A1 duality result. A1 duality
may be accidental cancelation in g1 and F1. Perhaps can use this
in the motivation for RSS section.
- After Frank rewrites, he will recirculate to collaboration.
- Oscar here on Weds-Thursday.
08/28/06
- Shige:
- Working on smeared neutron cross section = Deuteron XS -
smeared proton.
- Using 5752.515 MeV for E0, and kinematics from the ntuple vars.
- Peter: Asks if spectator nucleon is on-shell?
- Oscar: There is no off-shell correction applied. They are
using a convolution of W1 and W2 with momentum distribution. Will
also try some other prescription. Peter can provide his code for
a cross-check.
- Shige shows smeared neutron Apar and Aperp. He uses
DeltaSigma/(smeared neutron xs) and R1990.
- Peter questions why we don't use HallC R? Could smear
F1,F2 and get R from that.
- There should not be much difference between R1990 and R1998 at
our Q2, W. Difference should be at low x.
- Peter: his code 'externals_all.f' has improved QE for all
targets but deuteron.
- Mark notes that if our W-bins are big enough, we don't need to
(should not) unsmear the neuteron results. Average smearing
is about 100 MeV.
- Karl:
- Shows plot of Gamma_1.
- Now evaluating from the model at Q2=1.279
- Peter recommends to get revised version of Eg1b from Yelena.
Also that we should look at replacing contribution at threshold with
model, as they did in Eg1b. This can have big effect on d2.
- Oscar points out that E143 did high x extrapolation which will
be useful for us.
- Karl should look at gamma_0=intx^2 A1, using fit, not data.
- Propagate relative errors to fit result.
- Mark:
- Arenhovel will respon in 2 weeks. In meantime he will
continue using simple model for Deuteron in RC.
- Peter has arenhovel's code, so does Vipuli. there are two
versions.
- Peter also has Laget's code. He is allowed to run it, but
not share it.
- Peter will run the codes for Mark.
- Peter:
- For NE11 data, Laget looked better than Arenhovel, at Q2=1.7
unpolarized.
- Steve Rock created a parameterization of Arenhovel's
tables. It is in Peter's externals code: Option 3.
- Oscar:
- The proofs for the elastic paper are back. They look fine.
- We will not meet monday.
08/17/06
- Shige:
- Last week he found negative cross sections. Now he is
using new deuteron parameterization.
- Needs kinematic variable phi, but which phi to use for A_para ,
A_perp?
- Oscar : Phi-dependence only important for A_perp.
- Assuming R_n=R_p. Getting R from Frank's table.
- Oscar: probably better to use R=0.2 or R1990 instead, because
of all the wiggles in the Hall C R.
- Karl : will send Shige email regarding which ntuple variables
to use.
- Eric: Don't trust Deuteron cross section below W=1.15.
- Oscar : Steve Rock studied many different models for Q.E. There
was no report, but he produced a series of plots.
08/10/06
- Shige:
- Working on developing code and debugging.
- Procedure: Smears W1^p and W2^p and then creates smeared cross
section.
- Shige needs unpolarized structure functions for the deuteron.
- Frank : warns that the structure function quantities in his
deuteron files are actually proton quantities.
- Oscar : Shige can use the Niculescu/Stewart/Keppel
parameterization. The only assumption would be that R is
independent of A.
- Mark:
- Working on the RC for the deuteron
- Plot
- Needs radiated version of QFS. Karl will send his version.
- Will get the Q.E. parameterization of asymmetry from Arenhovel.
- Oscar:
- Arenovel is retired :(
- The tables Arenhovel produced for GEN only go to Q2=1.2 GeV^2
and E=3 GeV.
- Frank:
- Submitted prl to archives : nucl/ex and hep/ph
- Oscar points out a 'new' treatment of Target Mass Corrections
by Piccioni and Ritali (1998).
07/20/06
- Shige:
- Shows g1 and g2 D using 180 MeV bins.
- Needs dilution factor in Q.E. region.
- What model to use for the deuteron?
- Oscar has tables from Arenhovel at our kinematics.
- Shige finds that g2n is about 0.
- Frank:
- Received comments from Ingo.
- Discussion of Jlab acknowledgement requirements.
- Will circulate new acknowledgement.
- Will leave off c^2 in all momentums.
- Karl:
- Start work on sum rules paper: d2, GDH, BC, ELT, elastic to all
- Include the deuteron.
- E155x did ELT.
- No meeting next week.
07/13/06
- Oscar:
- Should g2ww include x=1? He will follow up on this.
- Frank
- Talked with EG1b people. They request we average their
Q2=1.2 and 1.4 GeV data. They claim there is also more data
coming.
- EG1a did not use a radiative dilution factor. This is why
the errors from Eg1b are worse.
- Discussion of PRL comments.
- Will drop data tables from appendix to prevent someone else
publishing before us.
07/06/06
- Oscar:
- The g1D and g2D listed in official tables were incorrect.
- We were not using the correct unpolarized structure functions
(either resonance or DIS).
- ~rondon/rss/analysis/deuteron
- Noticed this because raw Apar proton and Apar deuteron are
about equal, but dilution factor introduces a factor of two.
- Concludes we should use R1990 (which agrees with Eric within
error anyway).
- Overall about 1 sigma smaller g1. g2 doesn't change much.
- Deuteron Asymmetry seems to be dominated by the proton
contribution.
- Discussion folllowed regarding how to correctly apply DF.
- Elastic contribution to g1,g2: Oscar's result agrees with what
Karl got. Both disagree with Wally.
- Karl should get full DMT model.
- May have to double iterate on RC and smearing inversion.
- Spreadsheet: updated with new flags to evaluate at data
kinematics or at fixed Q2.
- Shige:
- Shows his latest g1d,g2d. Now better agreement with Hall
A.
- using 30 MeV bins.
- g2n constent with zero and Hall A.
- Frank:
- Re prl : d2 range inconsistent with plot data. Not much
impact. Will investigate further and fix.
- Eg1a/Eg1b data: Eg1b has worse statistics at our Q2 than Eg1a???
- Discussion of prl follows.
- Oscar discusses propagation of systematic errors for integrals.
06/28/06
- Karl:
- Shows 'final' pass VI results.
- Regarding A2 fit: Stops the fit iteration when the delta
resonance drops to ~130 MeV.
- For A1 : Using Oscar fit, Hall B fit, Fit to world.
- For A2: Using All fits except Maid, and the Soffer Limits.
- Oscar requests tables have internal/external stages added.
- Oscar requests standard deviation of d2 integrand from all
models used.
- Oscar:
- Sees difference in elastic contribution to moments/g1,g2 from
what Wally has in his paper.
- Requests Karl send the values he calculated at RSS Q2.
- Shige:
- Slac g1d is divided by two (per nucleon value)
- Still not clear how to get A1n.
- Oscar: there is a paper by Tony Thomas and Wally M. He
will send it to Shige.
- There is a problem with using constant w_d when correcting for
the D-state. But this led to only a small error in E155.
- Submitted his proceeding today.
- Frank:
- Try for next week to get PRL ready, but probably not ready till
week after.
- Mark:
- Already received comments from PRC on elastic paper.
- Mostly minor issues. Looks good.
06/22/06
- Karl:
- Suggests to try 16 parameter fit instead of 17. Also,
could stop fit iteration when the Delta width goes below some limit.
- Needs to talk to Sebastian or Keith regarding some of the Hall
B A2 models (DMT and Soffer/W).
- General consensus : use OR, Hall B, and world fit for A1.
Use all A2 models except A2 = 0 and Soffer limits.
- Shige:
- Asks for comments on his proceedings
- Sees big disagreement with his g1n and Hall A (X.Zheng data)
- Checked his code with 3 different fermi momentum
distributions. Finds negligible effect.
- Trying to figure out how to get A1n from A1p and A2d.
06/08/06
- Shige:
- Working on smearing the proton.
- Keeping relative errors constant through the process.
- Using 30 MeV bins now, may need to go wider.
- Shows g2n.
- What is binsize of Hall A duality?
- Oscar suggests looking at A1 A2 of deuteron and A1N, A2N.
- Eric: Peter found that Deuteron =(smeared proton + 0.6 smeared
proton) is good prescription at low Q2. Describes the Jan 05 data well.
- Oscar : constant factor over entire x-range may not be suitable.
- ~tajima/rss/ssf/note.ps (Oscar requests comments)
- Eric:
- R is still independent of nucleon # A for DIS. Suggests
we just use proton R.
- Systematic error on theory: suggests run several different
potentials. Find out if it a big effect. Oscar says this is
addressed in his technote.
- Mark:
- Has Shige been able to go back to unsmeared from smeared result?
- Karl:
- Shows new RC results
- Needs to produce the error matrix for the fit.
- Needs to fit sigma_TT, sigma_LT, but for short paper we will
use the A1,A2 fit, fixing the width of A2.
- Needs to talk to Vipuli to get latest data.
- Peter: There is low Q2 Aperp data from Bates and Nikhef.
06/01/06
- Shige:
- proton smearing: optimize run parameters getting V3 parameters
from Frank.
- Gets similar result for 15 and 30 MeV Bins.
- Not sure how to propogate errors through the smearing?
- For now, keeping relative errors constant.
- Will create web page summarizing his work.
- Oscar: Smearing (nucleon fermi motion) is the perfect duality.
- Shows plot of smeared g1n, may need to go back to 30 MeV
binning or larger.
- Karl and Oscar will send g1,g2 world data to Shige.
- Shows smeared g2
- May need to use a variable binsize.
- Oscar:
- Using elastic contribution to improve duality. Discussing
with Thia and Rolf.
- TMC make pdf value for g1 at 0.8<x<1 non-zero.
- Different approaches to solve this problem can have huge impact
on F1. It's just not clear how to add elastic to the PDF.
- Discussion with Wally
regarding elastic.
05/24/06
- Shige:
- Working on smearing proton.
- Trying to unsmear smeared proton.
- Got fit program, needs Phi from Frank (kine weighted vars are
in "kineperbin" files).
- Oscar: suggest to try with finer binning.
- Oscar:
- Discussion with Cole Smith : there are 19 3/4 resonances.
adjusts multipoles wrt/ Liang's code.
- 1511 MeV : Eta production threshold.
- Wally, Thia and Rolf paper.
- MEK_DUAL.EPS in Oscar's directory:
rondon/rss/analysis/systematics/
05/19/06
- Shige:
- Working on DeltaSigma smearing
- D-wave function from Oscar, who wrote a technote.
- Following technote, debugging code.
- Shows plot of smeared proton deltaSigma using Paris
potential. Will run with other two potentials.
- Using fit function of Oscar for A1 A2 to get g1,g2. With
Eric's fit can get Delta sigma.
- Results look reasonable.
- Using constant Q2, wants to use actual Q2.
- Next subtract from Deuteron data.
- Mark: suggests to try to reproduce smeared quantity w/
fit. Try to go from smeared to unsmeared. Asks Karl to give code
to Shige.
- Oscar: can try using either 3 or 4 peaks.
- Shige is also working on his DIS proceedings, due by end of
June.
- Mark:
- Put off the elastic paper for now.
- Only got comments from Ingo.
- J.P. Chen suggested adding stat. and systematic in
quadrature.
- Generally, we prefer keeping them separate, but Mark has mixed
some of them in the plot for the other experiments.
- Oscar:
- 4 new students on NMR.
- AO can give asymmetries >1
- Cole Smith did not like us fitting A1, A2 instead of cross
sections.
- Oscar pointed out the E143 paper which shows A1~sigma_TT' ,
A2~sigma_LT. So they are directly
related to the multipoles.
- Because of this, his objections to our fit have been withdrawn.
- ~rondon/rss/analysis/rss-eta-a1.eps, rss-eta-a2.eps
- Cole Smith ran Maid at our kinematics, got same results as Karl.
- We could do a multipole decomposition.
05/11/06
- Oscar :
- Wants to finish by June deadline. Discussed with Donal
and Don, July probably ok, and will free Shige and Karl to work on
other projects (Frost)
- Discussion of Duality.
- We will invert our duality integrals to match the world
convention.
- Created a Makefile for Radiative corrections. Can be used
for debugging: /group/rondon/rc/subs/src
- Karl
- EG4 almost over. Working majority of time on RSS again.
- Updated minutes (finally)
- RC started again.
- Shige:
- Discusses OVC can for SANE runs.
- Had discussion with Simonetta in Japan: large x resummation
should be included in duality integrals.
03/23/06
- Karl
- Oscar suggests using the envelope of statistical errors to see
systematic effect.
- Needs to recheck his Radiation lengths using the final Packing
fractions.
- Frank:
- stat weighted average is much different than before, now gets
much better agreement with Mark. Frank weighs Q2,W with the stat
average of asymmetry.
- Karl will do RC at central kinematics, then Frank can redo the
stat weighting.
- Oscar:
- g1 has not changed significantly since first try.
- Now Eric has new model, with big difference at Delta.
- P.F. is very insensitive to the model, but DF will vary.
- Frank will get commitment from Eric.
- Oscar: single pi production near threshold might be useful for
threshold.
- Shige:
- Method of combining df for high/low weighted average is not
equal to combining all into one bin and then calculating error.
- Solution: combine high and low ntuples (weighted by charge for
each case) then dont need to combine.
- Proton smearing program : comparing several non smeared xs
should have something next week.
03/16/06
- Shige:
- 20 min talk at Japan, Vipuli also.
- Proton smearing calculation: needs some kinematic variables.
- Mark:
- Questions the statistical propogation of errors.
- Oscar:
- two new notes on Radiative corrections. The second is an
example of how not to do it. Can't explain why new f_rc <>
(old frc)^2 but otherwise very clear.
- Mark: model systematics comes into DeltaRC only, otherwise in
ratio.
- Ionization is already taken care of in the engine.
- Straggling is not: Most urge to ignore straggling since it is a
fraction of 2 MeV.
- Eric :
- has newest version of his fit. Changes:
- Q2 dep of FF
- no extrapolation to real photon point
- Best BR for doing relativistic B-W and threshold effects.
- Should be significantly better at threshold
- pi, 2pi, eta
- We'll compare to previous version to see if we need to
implement it.
- renewed request for error on Eric's fit. It's possible,
but he needs time.
- Peter:
- W<1180 MeV we have no measurements, error is so big. Similar
to RSS results.
- look at polarazibility gamma_0
- Vipuli working on this problem for hall C, can discuss with
her, she has 12 models of g1.
- Peter has smearing routine for radiative corrections.
works pretty good. Eric has code from Wally which is very
sophisticated.
- Peter will provide his code to Shige, but it may also be useful
for RC.
- Looking at N15 elastic, Karl will send some info he gathered
for PAC.
- Marc:
- Has new version of elastic PRC
- got comments from Peter
- will add more comments on 2gamma effect.
- will add formulae for cross section.
03/09/06
- Oscar:
- Updated systematic errors
- Karl
- Looking for error in RC version 5
- Oscar
- f_rc : many different definitions. E155 covariance of fit from
models which is very different from our deficintion. Should only
be used in statistical error propagation, and should reflect the net
change in counts in a given bin from radiative corrections.
- f_rc ~ sigma_born/sigma_T
- Frank
- will send out draft of PRL with appendix.
- Karl should send the fit's diagonal matrix to Frank.
- Frank doesn't want to circulate yet.
03/02/06
- Frank:
- Discussion regarding PRL. Final comments before sending
to collab.
- Karl:
- Discussion regarding RC systematics. Will send table to
Oscar. Also needs to evaluate the statistics weighted average for PRL
table.
- Looking at lowest W-bin data. Trying to salvage so we
don't have to discard this large error point.
- Shige:
- Not present (working in Hall A), but posted new results for
Deuteron DF on his webpage.
- Oscar points out that this DF is consistent with maximum
expected (6/21 for N15D3).
- Frank will generate new deuteron asymmetries.
- Perp-Top is still TBA. Mark suggests it is not high
priority since recovering this data will only decrease error bars by
8%. Would prefer that Shige work on the neutron extraction.
- Mark:
- Would like to bundle up all useful background info (tables, fit
parameters, etc.) and put in an appendix for Los Alamos archive version
of PRL.
- Oscar:
- Discusses d2 value. Looks like d2 doesnt depend much on
Q2. Still many sigma from zero.
- Mark brings up "factor of two" issue. He wrote a note
about it previously, requests that we review to ensure general
agreement.
- Discusses correlations of systematic errors. Refers to
"excellent treatment" of said issue in T.J. Liu's thesis
(E143). Bottomline, no big change in his estimate of sytematic
error.
- Mentions that Eric has requested we reference the Hall C
elastic Rosenbluth paper (in our elastic paper?).
02/23/06
- Karl:
- Discusses pass V RC results.
- Not clear how to establish systematic uncertainty. Right
now looking at variation due to choice of model input (Oscar's model,
Maid, and Hall B).
- Oscar suggests to discard Maid, atleast above W=1400 MeV where
we know it is unreasonable. For W>1400 MeV, use the difference
between Oscar model and Hall B. Below 1400 MeV can use the variance of
the three. For overall number divide by the additive RC
correction and then average. Believes the elastic uncertainty is
small (~1%).
- Notes that g1,g2 are significantly smaller than what he found
in Pass IV. Oscar points out that this is expected since the DFs
are now bigger than previous pass.
- Oscar:
- Working on systematic evaluation for PRL.
- Finds a large systematic for A1, A2 (10% and 30%). The
kinematic factors seem to be unfavorable, especially d'.
- Regarding the large x resummation: Simonetta provided estimate
for the global integral ratio. The ratio should be increased by
factor 1.214.
- We will mention in text, but leave duality table unchanged.
- Compared Karl's pass V tables with his own and Frank's.
Found agreement to about 0.2% for almost all bins. The exception
is in bins where the Q2 varies dramatically due to the momentum overlap.
- Frank : points out that the peak positions in the fit graph do
not match the values the fit code produces. There is a small
shift. Oscar has noticed this before but will reexamine.
- Oscar did not take correlations of uncertainties into
account. May reduce systematic significantly.
- Points out that fit is basically zero for first three W points
in d2, while the uncertainty is quite large. We may be taking an
unneccessary hit in overall systematic.
- Karl concerned that fit does not follow the points very well in
this region, will look into it.
- Frank:
- Discusses PRL
- Working on space constraints.
02/16/06
- Frank:
- Regarding rules of affiliation, PRL wants only who paid you to
do work listed.
- Will update his script to use latest Nitrogen asymmetry files.
- Working on RC paragraph, other comments for paper.
- Mark:
- Regarding nitrogen assymetry correction: between version 5 and
6 the proton xs might have changed.
- Believes first point of asymmetries should be discarded.
- Karl:
- Released preliminary results for RC pass 5. Hopes to
finish within week.
- Oscar and Frank will proceed with these preliminary
results, update if there is a big change.
- Oscar:
- Had discussion with Simonetta Liuti on usage of Nachtman
variable. She is a leading investigator of duality and it's still not
resolved if Nachtman is appropriate. Her opinion is that in the
integral it is only a dummy variable.
Believes it is proper for us to state that we find
better agreement when using Nachtman in the paper. Oscar's
integral results do not indicate the Nachtman behaves simply as a dummy
variable.
- Large x resummation: She would need 2 weeks to recode her
procedure to directly correct g1. Instead she will give Oscar a
parameterization in the next few days.
- We'll reference S. Liuti, Bianchi et al in the paper and thank
her for discussions.
- In the future, it will be crucial to reduce the PF uncertainty
(0.37*1.77*5% in his note). Could achieve this with 6mm disk
targets instead of pellets.
- Wants to move on Mark's PRL quickly.
- Will be here next week for GEN.
- Shige:
- DF systematics: 4.8-4.9%.
02/9/06
- Shige:
- Regarding the systematics due to the nuclear model: Finds 2.4%
for
high P, 3.3% for low P.
- Now gets a total systematic for D.F. of 5.3%., detailed on his
webpage.
- He will write a formal document to summarize.
- There seems to be general agreement that 5.3% is consevative.
- Oscar: mentions that Shige will need to redo the Deuterium D.F,
since QFS has changed.
- Frank:
- Working on applying the latest D.F. to the raw
asymmetries.
- ifarm machines very slow.
- Mostly complete, should be done in next day or so.
- Oscar:
- Discusses paper
- Open question: Implementation of the large x resummation
(correction to the TMC).
- It becomes most important at large x.
- Necessary for unpolarized structure functions. Without
it, global duality doesn't work.
- Details in paper by S. Liuti (UVA) et al.
- The issue is that the correction should be applied directly to
the PDFs. We can't do that since the code Oscar uses outputs g1
directly.
- Oscar will ask Simonetta to provide a parameterization that can
be applied directly to g1.
- This should be the last open issue regarding our duality
conclusions.
- Regarding TMC: Using Peter's code which agrees with published
paper
results. It's not clear what effect the TMC have on our
twist-3/d2 conclusions, since some of g2bar is from TMC. Would be
a problem if TMC differed for g1 and g2. Refers to X. Sung paper
:"Modified g2ww formulae with TMC"
- Still not sure if we should use/mention the nachtman
variable. Both the Bloom-Gilman and DGLAP papers mention that
they find improved duality when an "improved" variable like nachtman is
utilized. We many want to mention this in the paper, since we
also find improvement when using xi, but don't change the results
otherwise.
- Mark: Prefers we leave it out, atleast till we speak with Wally.
- Frank:
- Discusses several questions regarding the PRL.
- Points out that there are two points with very similar x in our
plots, due to the overlap of the high and low momentum setting.
Would like to average them.
- Oscar mentions that the PDF errors are not resolved yet.
02/2/06
- Oscar:
- Finds good agreement with preliminary hall C and our own
carbon data (field off) by tweaking DIS part of QFS.
- Scale factor of 0.92 applied to DIS part of QFS.
- Continuosly adjust QFS, no discontinuity now between low and
high momentum.
- ~/rss/analysis/qfs_dis/c_no_b_mc_data_opt_dis.eps
- We (i.e. Shige) will need to run MC one more time w/standard
P.F.
- Should be last modification to proton Apar Aperp.
- Shige
- Has already recalculated the P.F. There was no big change.
- Also did DFs : ~1% change at low W, 3% change at high W.
- will need to double check everything, but looks final.