γ -charge particle correlation analysis

1. γ-charge particle correlation analysis PrithwishTribedy, Arindam Roy (VECC)

2. Motivation 1. The charged particles are measured from the FTPC and photons from the PMD at forward rapidity. Correlation between productions of charged and neutral pions have been studied at top RHIC energy. 2.The energy dependence of the isospin fluctuation of pions in BES would be an interesting study in the context of phase transitions .

3. Issues addressed in the following presentation : • AuAu 200 GeV Run 7- Run 10 comparison • PMD – FTPC West correlation

4. QA plots & data cleanup

5. Run 10 data <ηch> <Nγ> <Nch> <φch> <ηγ> <φγ> 1 sigma cut applied to remove outlier runs <DCAch> <pT ch> <nCellγ>

6. Checking consistency with Run10 data Run 10: AuAu200 Prod: P08ic Stlib: SL10K st_pmdftp_ Events : 3.5 M Centrality: ReMultCorr Bad Runs : Alex-Hiroshi list + PMD-FTPC list |Vz|<5 cm |vpd(Vz)-TPC(Vz)|<4 cm All standard cuts of PMD-FTPC

7. Removing bad events for PMD using cuts of CPV (standard technique)

8. The PMD bad events are removed by putting a cut on cpvfrac (= cpvadc/cpvcluster) We use cpvfrac >1.8 for our analysis

9. Some more cleanup Using #primary vertex cut. npV=1  better cleanup

10. Looks clean except for peripheral events.

11. Run7-Run10 looks consistent Some difference may be due to some bad-events in the peripheral collisions.

12. PMD & FTPC East – FTPC West comparison Issue 1 : Difference in multiplicity even in same acceptance (Run10 is better ) Run 7 ~40% Difference In multiplicity Run 10

13. PMD & FTPC East – FTPC West comparison Issue 2 : Contamination effect makes direct comparison misleading • GEANT Simulation shows 30% of the photons might contain different contamination in the same coverage which can’t be completely removed. • So some of the photons from PMD include FTPCE tracks. So PMD-FTPCE correlation will be more than PMD-FTPCW. Common coverage <NPMD> = α <NFTPCE> + εγ <Nγ> <NPMD> and <NFTPCE> are average measured multiplicities from PMD and FTPC East. <Nγ> is actual photon multiplicity in the coverage considered, εγis photon detection efficiency. α Unknown contamination factor. FTPC W

14. Correlation of PMD with East and West FTPC : comparison It can be easily shown that the contamination will affect not only the same side correlation but also the opposite side correlation in different way. One can’t get rid of the unknown contamination factor by algebraic manipulation.

15. Correlation of PMD with East and West FTPC : comparison from Run10 data • ΔCorrWest-East • = Correlation (FTPCW-PMD) • Correlation • (FTPCE-PMD) • Depending on the value of unknown contamination factor it is not possible to conclude which side has more correlation.

16. Summary Run10 comparison: Run7-Run10 data are consistent, although some cleanup issues still remain with Run10 data. PMD-FTPCW (away-side) correlation: -It is hard to make a conclusion by comparing PMD-FTPCW and PMD-FTPCE correlation. -The difference in correlation between FTPCEast and FTPCWest depends on the unknown contamination factor, alpha. Higher correlation with FTPCWest would have indicated interesting physics signal where as higher correlation with FTPCEast would indicate dominance of resonance and jets etc.

17. Backup slides

18. Results for the observable νdyn Results for Top energy (systematic error bars are included) Energy and centrality dependence of the observable νdyn νdyn is a measure of dynamical fluctuation, non-zero νdyn dynamical fluctuation Non-zero νdyn is observed over wide range of centrality and energy.

19. Observation : (charge-dependence) γ-ch fluctuation result is very different from positive-negative charge fluctuation.

20. Generic expectation DCC expectation Observable r_{m,1} shows : Deviation from Poisson is small, result is consistent with particle production from equilibrated matter. (hydrodynamic evolution).