Spin PWG
This is a feed of Drupal items targeting the "Spin" Audience.
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.
A_LL Details
Details on the A_LL result and the systematic studies:
The result in numbers:
| Bin | <p_T> [GeV]
Neutral Pion Paper: 2005 ALL & <z>Neutral Pion Paper for 2005 data: Final Results. There are two spin plots planned for the paper, one with the 2005 A_LL and one with the <z>. Group Meeting UpdateProgress towards a measurement of A_{LL} for charged pion production opposite a trigger jet using data from the 2006 STAR run. Goal is to present this measurement as a function of Update 2008-08-28: added data/MC comparison plots Cross Section AnalysisOn the pages listed below I'm going to try to keep track of the work towards measuring the cross section for inclusive pion production in pp collisions from run 6. I'll try to keep the posts 2008.08.14 Shower shape with bug fixed dd-libraryIlya Selyuzhenkov August 14, 2008 Data sets: |