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    Hadrons in the Nuclear Medium
    March 7-10, 2000

    Dear Colleagues,

    It appears that several issues have emerged as doable and reasonably easy to explain to the community as possible key elements of the 12 GeV program.

    Color Coherence and Color transparency
    study of the fundamental issue whether hadrons are produced in point like configurations in elastic electron nucleon scattering at large Q.

    Several complementary experiments would be possible:

      (a) A(e,e'p) - in this case the whole kinematic range available at 12 GeV will be covered (up to $Q^2 \sim 16 GeV^2$) (R.Ent talk). There seem to be very little further work to be done along these lines for preparation of the final document.

      (b) Double scattering experiment D(e,e'p) - K.Griffoen has demonstrated that $Q^2 \sim 10 GeV^2$ would be possible at CLAS.

      tasks to study : can CLAS push to higher $Q^2 \sim 16 GeV^2$? Can one reach 16 GeV^2 with a two spectometer setup like in A(e,e'p) ?

      A code necessary to estimate the counting rates is available, so it will be possible to do the necessary experimental studies in both cases.

      (c) Coherent vector meson production - issues: study the hadronic structure of photons (real and virtual) and the onset of the color coherent regime. - Experimental side was presented by S.Stepanyan

      It appears that a feasible idea is the study of the interactions with the lightest nuclei either in coherent or in double scattering mode. Here the issues are: (a) up to what Q^2 CLAS can do this (b) What are optimal nuclei: deuteron, $^3He$, $^4He$? (c) would a recoil detector improve the counting rates? Here we need more interactions between T & Exp.

      (d) Hard Meson photo/electro-production off Lightest Nuclei

      Study the feasibility of high momentum transfer electro/photo-production of mesons from nuclei. Similar those which H.Gao discussed in the workshop. This topic will require a substantial contribution from Haiyan.

      It would be nice to consider in addition to the reactions, discussed by H.Gao at the workshop, coherent and incoherent electroproduction of pions and charged $\rho$ mesons.

    Tagged structure functions:
    Fundamental issue:
    Do bound nucleons have the same quark-gluon structure as free nucleons? How to make a "free neutron target"?

    The theoretical suggestions in this case are pretty well formulated. Codes exist to calculate the counting rates.

    The main issues here are the feasibility of a dedicated detector for tagging at low momenta and the possibility to carry out the same measurements at larger recoil momenta. Here the main issue is an exp. one. Depending on the experimental feasibility we can decide how to proceed.

    Deep inelastic scattering off nuclei at x>1 and Q^2\ge 15 GeV^2.
    Fundamental issue: Are there superfast quarks in nuclei - answering this question would provide an important clue to the quark structure of short range correlations.

    Experimentally this is feasible (D.Day's talk). A new idea is to analyze whether one can measure coincidences in this case - if its possible one will certainly learn more.

    This is two step problem - do theory predictions - MS and Misak Sargsian are willing to do the study, and then one would have to look at the experimental feasibility.

    Study of short-range correlations in nuclei
    - certainly fundamental.

    the main task is to provide examples preferably based on already collected CLAS data. Ideas - backward protons, \Delta's and forward- backward correlations. Here we need much more interactions between Th. and Exp. So a suggestion is to focus in terms of joint th.-exp. efforts on the above issues.

    Experimental side presented by L.Weinstein (\Delta's though from a different angle) and nucleons - informally discussed by K.Egiyan.

    It would also be important to addess a more broad program of studies of exclusive two body

    high Q^2 reactions on the deuteron. For example: study deuteron break up at the highest possible Q to probe high-momentum components. This is complementary to color transparency aspects discussed above.

    Perhaps we could think of a dedicated deuteron group.

    The Framework of the meeting
    We propose to meet in various combinations during the week of March 7-11 at FIU. Depending on who can come and for what periods of time we will build a program of discussions.

    Preferably we will spend a day on a subject going through informal discussions and presentations of results and idea.

    If necessary we will come back to these issues in a day.

    The tentative schedule of the discussions will be

    7-March - Tuesday "Study of Color Coherence/Transparency Phenomena"
    8-March - Wednesday "Study of Tagged Structure Functions"
    9-March - Thursday "Study of Superfast Quarks in Nuclei"
    10-March - Friday "Study of Short-Range Correlations"
    11-March - Saturday "We may vote not to go to the beach
    if more subjects for discussion will be left"

    Please let us know who would like to come and work on these issues. We also open to suggestions of other issues.

    Looking forward to hear from you soon

    W. Boglin M.Sargsian M.Strikman

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