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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