Spin PWG
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Jigsaw Inv Mass Plots (final)
As noted here and here, the pion peak is difficult to model using single-particle MC. In single particle studies, the pion inv mass peak is reconstructed to narrow.
BEMC Related Studies
My initial attempt at pinpointing the causes of the 'floating' pion mass examined, as possible causes, the fit function, an artificial increase in the opening angle, and the BEMC energy resolution.
Spin Physcs PWG
phone 317-263-8800 1 077795# 1, at 17:00 (GMT), duration : 01:30
Agenda posted at meeting list
Run 9 triggering
Carl has prepared a trigger description for 200 GeV.
SPIN 2008 Talk for Neutral Pions
Hi all-
My Spin 2008 talk and proceedings can be found below.
Update:
v2 reflects updates based on comments from SPIN pwg and others
Concerning the 'floating' mass peak and Zgg
Objective:
Explore the pt-dependent mean mass position in data and MC and perhaps draw some conclusions about the quality of our simulations.
Details:
Special Attention Ought to be Paid to Zgg
The collaboration has concerns about the SMD, and not without reason. They, they SMDs, have been notoriously hard to understand and model.
Mean pT in z bins
I looked into the mean transverse momentum for pions and jets in each of my z bins. First, here’s a comparison of data (black points) and Monte Carlo (red lines) for the BJP1 trigger:
It looks good to me, so I went on to compare simulations for jet patch and minimum-bias triggers:
In hindsight, this plot makes perfect sense — the trigger hardens the pT spectrum for the jets, so each JP z bin (which integrates over 10-25 GeV) has a higher average jet p_{T} than the MB version.
Now, this 3 GeV p_{T} shift means that we’re biasing the sample in each z bin towards higher x. This is almost certainly the source of the observed trigger bias in the Monte Carlo asymmetries for π+. So, what’s the next step?
Cut Variation Tests
Goal:
To test the stability of the cross section measurement to changes in the analysis cuts and, if necessary, assign a systematic uncertainty for cut variations.
Preliminary Result
Longitudinal double-spin asymmetries for inclusive charged pion production opposite a jet
Jigsaw Fits (2nd try)
Following up from this post concerning the modeling of the invariant m
Run 6 Data / Monte Carlo Comparison
Partonic Cross Sections
xsec = {
'3_4' : 1.302,
'4_5' : 3.158E-01,
'5_7' : 1.372E-01,
'7_9' : 2.290E-02,
'9_11' : 5.495E-03,
'11_15' : 2.220E-03,
'15_25' : 3.907E-04,
'25_35' : 1.074E-05,
'35_45' : 5.000E-07,
'45_55' : 2.857E-08,
'55_65' : 1.451E-09
}Normalization Procedure
I calculated the integrated luminosity for my dataset (5.43 pb^-1) and scaled all event- and jet-level histograms by that amount (in mb^-1 to match the partonic xsec numbers above). For the track histograms I added a multiplicative factor of 0.82 to account for imperfect PID efficiency in the data. I neglected PID contamination.