Re: A note on mass resolutions in GlueX/HallD

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

Hall D PID Mail List:

Hi Elke,

I chose a Gaussian to compare directly with the E852 results which were
fit with Gaussians.  


Paul


On Sat, 2008-03-15 at 16:20 -0400, Elke-Caroline Aschenauer wrote:
> On Sat, 15 Mar 2008, Prof Paul Eugenio wrote:
> 
> Dear Paul,
> 
> thanks for the plots very nice. espcially that the resilts from Alex and
> you are so close. I have a small question would it not better to fit
> the distributions with a breit wigner instead of a gaussian.
> I think it would be also good to use some background function below the
> fit should improve a lot and the width I guess will become smaller.
> 
> cheers elke
> 
> 
> > Date: Sat, 15 Mar 2008 13:02:24 -0400
> > From: Prof Paul Eugenio <eugenio@fsu.edu>
> > To: Alex Dzierba <dzierba@indiana.edu>
> > Cc: halld-pid@jlab.org, GlueX Tracking <halld-tracking-hw@jlab.org>,
> >      GlueX Software <HallD-Offline@jlab.org>
> > Subject: Re: A note on mass resolutions in GlueX/HallD
> >
> > 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
> >
> 
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-- 
--
Prof. Paul Eugenio
Department of Physics
Florida State University
Tallahassee, FL  USA

850-644-2585
eugenio@fsu.edu