Re: A note on mass resolutions in GlueX/HallD

[Prof Paul Eugenio <eugenio@fsu.edu>]

Hi Alex,

Last night I ran some 3pi generated event through the new smearing
functions.  The events were generated with e^-5t distribution, and
weighted with Adam's 3pi cross section what we used in the blind PWA
studies.  I subjected these events to fiducial cuts where events were
accepted if  0.150 GeV < p_pion < 7 GeV and  1 deg < theta_pion < 140
deg.   These events were then smeared using the new functions.  I found
that the new routine return unsmeared momenta above 7GeV so I cut these
out.  I also smeared the beam by an expected(RTJ) 0.06% (0.02%
accelerator + 0.04% tagger).

I have attached 3 figures.  The file 3pi_newSmear.pdf shows the t, 3pi,
2 PiPlus, 2pi, mmsq, and cos_GJ.   A fit to the mmsq over the same range
as in your report results in a sigma of 0.27 GeV^2 (chisq/dof = 3.7).
This is in good agreement with your result (0.33 GeV^2) and shows a
slight improvement as expected.  

In your report you compared to an e852 sigma of 0.31 GeV^2. I came
across a different published E852 mmsq sigma result.  In Phys. Rev. D65
072001, the mmsq has a sigma of 0.26 GeV^2(I have attached a clip from
the paper in the file e852-3pi-mmsq.jpg).  Note that E852 fit was over a
wider range. I tried a fit over this same mmsq range.   The result was a
sigma of 0.30 GeV^2 but much poorer fit ( chisq/dof = 7.6 ).   See plot
in 3pi_new-mmsq-compare2E852.pdf.

Paul  


-- 
--
Prof. Paul Eugenio
Department of Physics
Florida State University
Tallahassee, FL  USA

850-644-2585
eugenio@fsu.edu

3pi_newSmear.pdf

e852-3pi-mmsq.jpg

3pi_new-mmsq-compare2E852.pdf