Are recoil polarization measurements of G{sup P}{ovr sub E}/G{sup P}{ovr sub M} consistent with Rosenbluth separation data? Page: 3 of 4
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to whether a different solution for the relative normalizations could be found
which brings the experiments into agreement without significantly decreasing
the quality of the fit. This was tested in two different ways. First, GM was
fit to the data, with the ratio of GE/GM determined from a parameterization
of the recoil polarization data (ppGE/GM = 1 - 0.13Q2). This gave a much
worse fit, increasing the total x2 by 69 for the fit to 301 cross section data
points. The Rosenbluth data do not reproduce the recoil polarization data
with only minor adjustments to the relative normalization factors. Fixing the
ratio of GE/GM to match the recoil polarization measurements gives these
data more impact on the fitting then they should have and ignores their
uncertainties, so this test likely overestimates the inconsistency. A global
analysis including both the cross section data and the GE/GM polarization
measurements from fig. 1 (including their statistical and systematic errors)
also gives a significantly worse overall fit, though not as bad as when the ratio
is fixed in the fit (16 data points are added to the fit and the total x2 increases
by 49).
Finally, it has been noted that individual extractions of GE/GM from
recoil polarization measurements are inconsistent. However, these extrac-
tions often involve combining two or three data sets that cover different e
ranges, which requires determining the cross-normalization between experi-
ments. While various procedures have been used to determine these normal-
ization factors, the uncertainty in the normalization is often not taken into
account in extracting GE and GM. Thus, it is difficult to verify the consis-
tency of the underlying cross section data based on these extractions. If one
examines only experiments where a single detector covered an adequate range
of e to perform a Rosenbluth separation, these experiments are consistent with
each other and give results similar to the previous global fits (although with
significantly reduced precision). One can increase the amount of data avail-
able by including experiments where multiple detectors were used, but where
direct cross-calibrations were possible within the experiment. Again, this set
of experiments give consistent results, and are in good agreement with the
cross section global analysis. The inconsistency of the Rosenbluth extractions
appears to come from the assumptions made when combining data sets at
different e values, and does not indicate a fundamental inconsistency between
the different measurements.
Even if the recoil polarization result is correct, and the problem lies with
the cross section data, we must still understand the problem with the Rosen-
bluth measurements. If the recoil polarization data is correct, this implies
that there is a problem in the cross section measurements that introduces
a systematic e-dependence in multiple data sets. Even with perfect knowl-baryons2002'gegm: submitted to World Scientific on April 30, 2002
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Arrington, J. Are recoil polarization measurements of G{sup P}{ovr sub E}/G{sup P}{ovr sub M} consistent with Rosenbluth separation data?, article, May 16, 2002; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc742509/m1/3/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.