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Like-sign and unlike-sign asymmetry

In the ongoing effort to figure out what's wrong with my calculated 2005 asymmetries, the like-sign (A_ls) and unlike-sign (A_us) asymmetries, as defined 

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.

Embedding tests: 9.2 GeV Au+Au in SL08d

It was reported that the tuning of the scale factor (Normalization Factor in TRS) was giving different results in SL08c library at PDSF and RCF (see

constructing a webpage

 Bernd has asked that I put the details of my analysis into a static webpage (not a blog post like this one), but in order to get things in order in my head, this is where I'm starting.

MuKpi.C : micro-vertex code

 Brief introduction to the code

group meeting update

 Using the yield formula I showed at the last meeting, I can now generate yields for the xs data that have better-contained error bars and are also far more accurate when the signal-to-backgro

Group Meeting Update

Progress 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 z, defined here as p_{T}(pi) / p_{T}(trigger jet).

Update 2008-08-28: added data/MC comparison plots

Cuts Summary

This page summarizes the effect of each major cut in the 2006 jet+charged pion analysis. Each plot is obtained by applying all other applicable analysis cuts except the one being illustrated.

Figure 1: Black is TPC z-vertex for all BJP1-triggered events, Green is the TPC z-vertex distribution for events in BBC timebins 6-9, and Red is the TPC z-vertex distributions for all charged pion tracks (inclusive, no trigger jet requirement).

It appears at first that the vz distribution of good tracks is broader than the BBC 6-9 distribution, but that’s not actually the case. Here’s the ratio of the red and green histograms from the above plot:

Figure 1b

The following histograms use positively charged pions from any spin state. Black lines are inclusive π+ passing all cuts except the one being shown, green lines are leading π+ opposite a trigger jet, and the filled green histogram shows the π+ accepted for the asymmetry analysis.

Figure 2: |η| < 1.0

Figure 3: |dcaG| < 1.0

Figure 4: nHitsFit > 25

Figure 5: nσ(π). It’s not possible to read off the efficiency from this histo because I actually use a time-dependent cut window based on the results of fill-by-fill fits to the nσ(π) distributions. Ideal world cut shown is nσ(π) [-1,2]

Here’s the ratio of the green and black histograms from that plot. The away-side spectrum has a relative lack of electrons but an increase in the p/K contamination:

Figure 5b

I should also add some more plots here documenting the cuts on jet pT, detector η, and N.E.F.

SSA vs. z

Asymmetries are defined as (Y,B):

SSA vs. Fill

Asymmetries are defined as (Y,B):