[E02013] GEN results and analysis

[Gordon D. Cates]

Andrei,

We are disappointed to hear that you no longer wish to be included on  
the author list for our publication.  As to your questioning of the  
analysis, we assure you that we have accounted for the points that you  
raised. However, we are happy to provide the additional information  
below.  We note also that it is our intention to include such details  
in an archival paper.

The changes found between the December and May drafts are almost  
entirely due to finalizing our calculations of the nuclear effects  
from 3He.  These produce changes in not only the "effective neutron  
polarization" but also as inputs to other parts of the calculations,  
such as the resulting cross sections, and the proton asymmetry.  These  
changes from our FSI calculation push the asymmetry down by the  
factors seen.  Indeed, the delay between the December and May drafts  
was due almost entirely to finalizing the calculation of nuclear  
effects.

We do apologize for the typo in the circulated Dec draft.  The A_meas  
for the lowest Q^2 point was not -0.071.  The raw asymmetries have not  
changed between drafts.

With regard to your comments on the proton dilution, you have raised  
several important issues, but we were careful to fully account for  
them in our analysis.  We would like to explain our approach more  
fully in the prl, but there is not sufficient room. This subject will  
certainly be discussed more fully in the archival paper.  To begin  
with, your comment that the flux of protons from 3He is in excess to  
the flux of neutrons, and that it cannot be taken into account by  
looking at proton data alone, is certainly true.  You may recall that  
our original proposal stated that such effects would be accounted for  
using a Monte Carlo approach of the sort that you are advocating.   
Indeed, such a detailed Monte Carlo project was realized and used, and  
included, among other things, a careful accounting of the various  
materials in our experimental setup (an issue raised in your email).   
We went beyond the proposal, however, in that we found an independent  
method for empirically determining the proton dilution utilizing  
studies of He-3, hydrogen and nitrogen targets, each of which have  
different ratios of Z/A.  This separate technique was in excellent  
agreement with our Monte Carlo, and greatly adds to our confidence in  
our results.  You may recall having heard all of this described in  
several Hall A collaboration meetings.   The general method of the  
analysis was detailed in Seamus' thesis, which can found at the  
following link:

http://www.jlab.org/~riordan/thesis/gen-riordan.pdf

Regarding the lowest kinematic point, we remind you of the many  
discussions at the full GEN collaboration meetings (not the weekly  
analysis meetings)  in which we collectively decided to put priority  
on the highest Q^2 points where the new physics lies.

After considering the above comments, perhaps you will consider  
rejoining the paper.  We are also happy to address any further concerns.

Best regards,

Gordon, Bogdan, Nilanga and Seamus

_____________________________________________________________
Gordon D. Cates,  
Jr.                                                           
Department of Physics
Professor of Physics and Radiology                                
University of Virginia
Director,  Institute for Nuclear and Particle Physics     P.O. Box  
400714
Phone: (434)  
924-4792                                                    382  
McCormick Rd.
email:  
cates at virginia.edu                                                
Charlottesville, VA, 22904
_____________________________________________________________



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