GDH Analysis Meeting





    Karl Slifer discussed the nitrogen dilution:
        Karl gave an update on his work for the nitrogen dilution analysis.
    For some of the kinematics, there is a problem with the BCM normalization.
    Karl's analysis agrees pretty well with Pibero's original analysis.  For 4 GeV,
    there is an offset that is probably caused by using the wrong density, since two
    different targets were used.

        The collaboration suggested that Karl add external RC corrections to the
    simulation code or use RC on the data, since the simulation code QFS only
    has internal corrections.

    Seonho Choi reported on the Referee report from the First PRL:
        One of the comments from the report is that the theoretical error for
    neutron extraction from 3He is underestimated at lowest Q2.  Original paper
    had 5%, now corrected with 10%.  There are three different conventions to
    define the GDH integral at Q2 > 0.  The collaboration will go with convention
    A so that the results can be compared with Chiral PT.

    Alexandre Deur gave an update on the raising tails seen in E94010:
        The problem involves the raising cross sections at large energy transfer
    that are not explained by radiative tails.  Alexandre considered two processes:
    multiple scattering and a two-step process involving radiative elastic scattering.
    Alexandre found that the multiple scattering contribution is negligible.  But the
    elastic scattering causes much larger cross sections due to a smaller angle and
    large elastic tail.  The effect was reproducible using a MC for GDH.

        The cause of the effect is scattering off the Be and Al windows.  Since
    the effect is unpolarized, it does not compromise past results.

    Zein-Eddine Meziani discussed the second paper on g1/g2 integration:
        The paper will include plots of g1 and g2 at fixed energies and constant Q2.
    It will also include plots of the  g1 and g2   integration and d2.  The collaboration
    decided to keep a plot of  Gammabj out, and maybe work with Hall B to write a
    separate Phys. Review C.

        Zein-Eddine wanted to have physics focused on higher twist, which was
    initially planned to be in the third paper.  JP and Zein-Eddine will discuss the
    issue more in depth after the meeting.

    Nilanga Liyanage discussed the third paper on twist expansions/duality:
        Nilanga is working with Wally Melnitchouk to extract the twist-4 term from
    E94-010 data.  Nilanga outlined the procedure that will be used in the
    extraction.  Zein-Eddine commented that this may be better to be in the second
    paper.

     The collaboration discussed the long term plan:
        For GDH, work that remains is to write a paper on GDH sum rule for 3He, and
    the long paper.  For A1n , there will be two papers:  one on A1n and a long paper.
 

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