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Search for P and CP Violation in Heavy Ion Interactions with the

STAR TPC Detector

Vasily DzhordzhadzeSTAR Analysis Meeting, BNL

October 16, 2007

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• Search for the CP violation in Heavy Ion Collisions predicted by D. Kharzeev [1] :

We are looking for a charge asymmetry relative to the Reaction Plane in HIC

• We are using specific angular correlations, the method developed by S. Voloshin [2] .

[1] D. Kharzeev, hep-ph/0406125 (2004) [2] S. Voloshin, PRC 70 057901 (2004)

Motivation

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• Analysis performed by Ilya Selyuzhenkov observed very significant effect of possible CP violation -> very exciting Physics

• Independent Analysis performed by Vasily Dzhordzhadze is reported in this presentation

• Both analysis get consistent results • We found CP violation effects which

needs further studies to determine the nature of the observed signals

Analysis

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Run 4 : 62 GeV: 13.4 M -> 8.3 M200 GeV: 18.3 M -> 7.1 M (Reverse Field)200 GeV: 5.4 M -> 4.4 M (Full Field)

Trigger cuts and Zvertex cuts, excluding Zvertex=0

Statistics used in the Analysis

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Run 4, AuAu 62 GeV ||<0.9, EP (+-)

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Run 4, AuAu 200 GeV, RF, EP (+-)

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Run 4, AuAu 200 GeV ||<0.9, FF, EP (+-)

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Run 4, AuAu 62 GeV ||<0.9, All EP

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Run 4, AuAu 200 GeV ||<0.9, All EP, RF

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Run 4, AuAu 200 GeV ||<0.9, All EP (FF)

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J. Dunlope, T. Hallman, M. Potekhin, Y. SemertzidisRecommendations to check:1. Agreement between two searches (done)2. Dependence on beam intensity (done)3. Dependence on Vertex position (done)4. Dependence on TPC Space charge

5. Dependence on TPC Pad efficiencies6. Simulation study

STAR Meeting 8/29/07

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Run 4, AuAu 200 GeV ||<0.9, Zvertex, RF

Zvertex, cm

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Run 4, AuAu 200 GeV ||<0.9, All EP, RF

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Run 4, AuAu 200 GeV ||<0.9, +/- EP, Vasily

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Run 4, AuAu 200 GeV ||<0.9,

2500

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Run 4, AuAu 200 GeV ||<0.9, All EP, Zdc<2500

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Run 4, AuAu 200 GeV ||<0.9, All EP, Zdc>2500

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• TPC Space Charge (In Run4 only simplified version of the Space Charge analysis is possible)

• TPC Pad Efficiency

TPC Study (not yet done)

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• MC simulation : Hijing+Geant+Reconstruction

MC Simulation

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• MC simulation: Hijing 100K

MC Simulation

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• MC simulation : Hijing 100K

MC Simulation

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• Available MC events (39K) analysis shows a necessity of error reduction by factor of ~10, which means simulation of ~1-5 M events for data sample of AuAu 200 GeV. Other data also needs an independent simulation

• Hijing simulation with and without flow is necessary to separate detector effects with the flow

MC Simulation

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• Exp AuAu 200 GeV - Run 4 23.4 M -> 12.0 M • Exp AuAu 62 GeV - Run4 13.7 M -> 8.3 M• Exp CuCu 200 GeV - Run5• Exp CuCu 62 GeV - Run5• Exp AuAu 200 GeV – Run7

• MC AuAu 200 GeV Run4 38.8K -> 21.2K• MC AuAu 62 GeV Run 4 100K• MC CuCu 200 GeV Run 5 54K • MC CuCu 62 GeV Run 5 189K • MC AuAu 200 GeV Run 7 100K

STAR Data & MC available

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• CP Violating signals are seen in 3 data samples of the Run 4: 62 GeV, 200 GeV (RF) and (FF)

• Two independent analysis shows consistent results in the limits of statistical errors

• In the limits of the stat. errors obtained results are in good agreement for high and low beam intensities

• With same limits result doesn’t depend on a AuAu interaction vertex position

• Analysis of Hijing simulated data was done; More simulated efforts are foreseen

• Study of the TPC Space Charge and Pad efficiencies influence on the signals are planned

Summary

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• Analysis of Run 5 (CuCu, 200 and 62 GeV) and Run 7 (AuAu 200 and 62 GeV) in planned. In this runs detailed study of the TPC space charge is possible

Summary (continued)