Hello Karl,
Thanks a lot for the inputs.
As I mentioned these plots are preliminary but I forgot to mention about the
sys errors being very incomplete. The model systematics are not included yet
at this point. I am still thinking for a good way to include sys errors that
come from model contributions. After that I expect sys errors to get bigger by
50% of their current values, maybe more on these quantities because of g_2 sys
error..
But, in the end, delta_LT plot was really just a practice. I had
parameterizations at hand and I just wanted to see how they come out to
produce the forward spin polarizabilities.. I was not thinking to show it
outside the eg1b community at all. On the gamma_0 plots, actually eg1b has
publication on that with the first half of the analysis already, I wanted to
see if I am getting similar results with my independent analysis after the
addition of new data sets and separate corrections etc... Eventually, I think
it is interesting to see how all the ingredients we collected, model, data,
param, etc..., come together and if the outcome makes sense and maybe get a
feeling of some physics after so much analysis...
Thank you,
- Nevzat.
>
> Hi Nezvat,
>
> The statistical precision on these data is very impressive
> and it's clear you've done a lot of nice work here for which
> you should be commended, but I have to say I'm very skeptical
> of the size of the systematics.
>
> g2 is a major (often dominant) contribution to both gamma_0
> and delta_LT, as shown in the attached plot. This estimate comes
> from the MAID model, but I'd encourage you to doublecheck with
> your own model and see for yourself. This can also be seen just
> from the definitions of the polarizabilities: g2 enters with the
> same weighting as g1 to delta_LT, and the factor 4M^2x^2/Q^2 in
> gamma_0 is also of order 1 at these kinematics.
>
> g2p is basically unknown in this region, and there's a wide
> divergence of all models that I've seen (simula, hall B,
> MAID etc), so I question how precise any of this can be.
> I'm sorry, but as a relative outsider to this analysis,
> I would expect the size of the systematics shown here
> to be small even for the missing transverse contribution
> to \int (x^2 g1) dx alone. The systematic from direct g2
> contribution to the polarizabilities has to be much larger.
>
> In short, I'd like to politely raise the question of whether
> it's a good idea to even evaluate these quantities from purely
> longitudinal data, when a major (often dominant) part of the
> integral is unmeasured. If they are shown, I believe it
> should be made clear how much of these quantities come
> from data and how much comes from models.
>
>
> best regards,
>
> Karl
>
>
>
> -------------------------------------------------------------
> Karl Slifer, Assistant Professor, Department of Physics, UNH
> DeMeritt Hall Room 335, 131 Main Street Durham, N.H. 03824
> 603-862-2827(office) 215-701-1122(voip) 757-871-6341(cell)
>
>
> On Thu, 16 Oct 2008, nguler@jlab.org wrote:
>
>> Hello,
>> I genereted some preliminary plots for the forward spin polarizability
>> gamma0
>> and also for deltaLT.
>> Gamma0 and deltaLT are calculated as described in:
>> http://arxiv.org/pdf/nucl-ex/0406005v3
>>
>> For gamma0, I put two different plots, one is in normal scale, the other one
>> is divided back to C kinematic factor.
>>
>> You will see plots for deuteron and proton and different plot types as you
>> scroll down in:
>> http://www.jlab.org/Hall-B/secure/eg1/EG2000/nevzat/RESULTS/FSP/
>>
>> I am thinking to show some of these plots, probably gamma0, in the DNP
>> meeting
>> if it is ok..? I will not show anything on the neutron extraction because we
>> decided it should be done carefully and slowly. So, these gamma0 plots will
>> be
>> the only addition over Spin2008.
>>
>> Best regards,
>>
>> - Nevzat
>>