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We meet July 11 at 11:00 a.m. in F226. Main point of order: Response
to PWG, long p paper. Here are the call-in instructions:<br>
<br>
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<li style="margin-bottom: 0.1em; ">First dial the conference call
facility:
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<li style="margin-bottom: 0.1em; ">In US, participant dials
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<li style="margin-bottom: 0.1em; ">Then enter the passcode<span
class="Apple-converted-space"> </span><b>8156718</b>, followed
by the # sign</li>
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<br>
<br>
I also enclose a summary of where I think we stand (previously sent
to the "editorial board" only):<br>
<br>
<blockquote type="cite">I wanted to give you an update and some
thoughts about where we are with the long proton paper:
<br>
<br>
1) I changed the discussion of the CC matching cuts in the paper
by removing large swaths of it - I agree with the PWG committee
that this topic is too technical for a general audience (but I do
believe we need to document what we did in the analysis note, so
it shouldn't be removed from there).
<br>
<br>
2) I think I'm pretty much done with the paper. You can find the
newest version and all files at
<br>
<a class="moz-txt-link-freetext"
href="http://www.jlab.org/Hall-B/secure/eg1/EG2000/Kuhn/LongPpaper/">http://www.jlab.org/Hall-B/secure/eg1/EG2000/Kuhn/LongPpaper/</a>
<br>
In particular, I copied the comments from the PWG committee
regarding the paper and my answers ("PaperComments.txt"). Our
biggest remaining task on this front, before going off to the AHC,
is fixing the figures listed in my file "FigsToBeFixed.tex".
<br>
<br>
3) Of course, this (#2) will be Rob's next task. For now, it is
most urgent that we complete our 3rd round of responses to the PWG
committee. As far as I know, Rob has answered most of their
comments which are listed at
<br>
<br>
<a class="moz-txt-link-freetext"
href="http://clasweb.jlab.org/rungroups/eg1-dvcs/wiki/index.php/Review_eg1b_note#Comments_to_paper_draft">http://clasweb.jlab.org/rungroups/eg1-dvcs/wiki/index.php/Review_eg1b_note#Comments_to_paper_draft</a>
<br>
<br>
(please post your response to the web, Rob!) with the exception of
the pesky "t-test question" (first comment on Chapter 7). Rob
promised to give us an update on his findings with regard to this,
but meanwhile I had a few more thoughts that I would like to pass
along - let me know what y'all think:
<br>
<br>
1) The first "suspicious" t-test result (see Table 7.1, p.116 in
the analysis note - Rob, please post this one as well!) is for the
inbending 1.6 GeV, pos. target polarization data - a systematic
difference between the results for the 2 HWP settings of about 15%
of the average statistical error. One can even see a hint of this
in Fig. 7.1 p. 114 - the green data points (HWP-) tend to be a bit
further away from zero than the the yellow ones (HWP+).
<br>
I can't believe that something changed "systematically" just by
changing the HWP (the difference is much too large for a parity
violating effect <span class="moz-smiley-s3" title=";-)"></span>;
so, I assume that what really happened was just the ELAPSING TIME!
Meaning, while we use a constant value for target*beam
polarization (PbPt - Rob, can you check that this is correct???)
for the WHOLE data set (over both HWP states), in reality of
course the target polarization changes over time. This could
explain why the asymmetries in one case are a little larger
(again, ONLY 15% of the average statistical error) than in the
other case. If this is correct, than the t-test discrepancy is NOT
a systematical error at all - precisely by averaging over both HWP
states (for both the data AND the PbPt), we get the right results.
So, if Rob (or anyone else - does anyone have the history of Pt
from NMR?) can somehow corroborate at least some part of this
argument, we should simply reproduce it as response to the PWG
committee.
<br>
<br>
2) The other suspicious t-test also involves the 1.6 (and 1.7) GeV
data (see table 7.4 p.119): The total 1.6 GeV data set (averaged
over all target polarizations AND all torus polarities) is once
again incompatible (by about 16% of the average statistical error)
with the 1.7 GeV outbending (only) data set (also averaged over 2
target polarizations).
<br>
To explain this, we should first note that the 1.6 GeV outbending
data are statistically insignificant, so we are really comparing
1.6 GeV inbending with 1.7 GeV outbending, which could mean that
the average Q<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>2</sup>
for any 2 formally identical bins that are being combined might in
fact be slightly different. Furthermore, there may be a small
change in eta and therefore in the contribution from eta*A2 even
going from 1.6 to 1.7 GeV (maybe Rob can do a quick numerical
check on how big an effect this could be). Finally, it is
important to realize that these 2 data sets have by far the
highest statistical precision, so 16% of the average statistical
error is clearly a small effect in absolute value. I think it
would be very helpful if Rob could calculate what the average
ratio for the KNOWN systematical error divided by the statistical
error comes out to be for the 1.7 GeV data set (say) - if it is
more than 0.16, we can claim that this t-test difference is
already accounted for by our quoted systematic error. If not, I
would have to come back to my suspicion that we are simply too
optimistic about our knowledge of PbPt -- maybe Rob can figure out
by how much we would have to increase the quoted systematic error
on that to match the observed discrepancy of 0.16*average
statistical error.
<br>
<br>
Hopefully, all of this can be done by our next meeting next week
(after which Rob will be moving back to VA and probably will be
out of commission for a while).</blockquote>
<br>
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