Dear Chi and collaborators,
being back from Ohio I'd like to report to you a little from my meeting
with Dan Phillips. My seminar presentation on BLAST showing data from all
channels was very well received and seemed to impress people a lot.
You can find a pdf file of my talk on the Blast website at
http://blast.lns.mit.edu/PRIVATE_RESULTS/Ohio_Seminar_060110/
It was satisfactory to see that renormalizing the theories for T20 with
(25.83-GQ(0))/(1+Q^2/M^2)^5 gives the most consistent T20 description
among all. We agreed that the so-renormalized EFT T20 curve should be
considered "the one". Also, it was highly appreciated the additional
constraint on the location of the node of GC set by BLAST.
Dan kindly requested to indicate an error band for the calculation. One
thing is to estimate how accurate the Qd correction would be. We agreed
that you should vary M between 0.75 and 1.5 GeV for the scale parameter.
In principle, also the exponent could or should be subject to variation,
say 5+- 1 or 2 ... you should try it and possibly add the variances due to
M and the exponent in quadrature.
The other uncertainties with the EFT calculation are the choice of the NN
potential (shown in Dan's talk at Bates of last January) and the MEC (in
particular pi-rho-gamma) considered in the current. Feel free to contact
Dan if you need additional calculations.
The third point we discussed was the timeline for the paper. Dan
understands that the Qd renormalization is quite important for the
interpretation of the BLAST data and therefore plans to write a short
paper on the Qd correction (a brief report). He would be able do do this
in spring and finish this by May. We discussed wether this paper on the Qd
correction or the BLAST data should be published first.
If the BLAST data is to be published first, we would probably use the
above Qd correction and quote it as "private communication". His
subsequent paper would be a justification in posterior ( ... and
effectively appear like fiddling the description of already-existing
data).
If Dan's brief report is published first, the BLAST paper could refer to
it when the curve is shown. Furthermore, the theory would appear to be
more predictive. Though the BLAST data would have triggered Dan's
reconsiderations, there is no fitting of data involved in the applied
Qd correction.
Dan and I therefore agreed that the BLAST data be better published after
Dan's brief report. As the BLAST steering committee decided that a BLAST
hardware paper be published before any other physics paper, and as the
kinematic offsets for the reconstructed angle is in the process of being
understood, I don't see right now why we could not proceed like this.
Let's work out the final results and the paper first and then evaluate for
how long we are willing to hold it up once it's ready.
Best regards,
Michael
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