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Identified “ High ” p T particle Correlations

Identified “ High ” p T particle Correlations. Ying Guo Wayne State University For STAR Collaboration. Hot Quark 2004. Outline. Introduction Data analysis Preliminary results Discussion. partonic energy loss. Motivation:.

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Identified “ High ” p T particle Correlations

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  1. Identified “High” pT particle Correlations Ying Guo Wayne State University For STAR Collaboration Hot Quark 2004

  2. Outline • Introduction • Data analysis • Preliminary results • Discussion

  3. partonic energy loss Motivation: • Get a better understanding of the high pT azimuthal correlations • Particle identified jet correlation study provides us additional information about the jet quenching and particle production mechanisms. • The strange particle identified jet correlation can be used as a probe to study the flavor dependence of the strong interaction and the fragmentation process.

  4.   Phys. Rev. Lett. 91 (2003) 172302 Phys. Rev. Lett. 90 (2003) 082302 nucl-ex/0407007 Medium Quench effect of the High pT particles Potential improvement of the original measurements • background subtraction method • variable away side range (Δφ)

  5. syst. error Away Jet profile Reconstruction down to low pT: 4.0 Gev/c<pT,trigger <6.0 Gev/c,0.15 Gev/c<pT,associate <5.0 Gev/c Fuqiang’s QM2004 talk.

  6. Uncorrelated background reshaped by flow Phys. Rev. Lett. 90 (2003) 032301 Same side Away side Sample of correlation Function: • Jet Fragmentation (near side) multiplicity • Jet quenching (away side) • Momentum conservation (away side) • Other particle production mechanism • Coalescence, recombination

  7. Nicolas Borghini et al. Phys. Rev. C 62, 034902(2000). Same Side Data Analysis Methods: Back Side Background pp: Au + Au: Gaussian Fit of back side: Cosine Fit of back side (momentum balance): Parameters are compared for different fits for two different pT cuts as the function of centralities

  8. Λ +h (charged hadrons) correlations AuAu and pp 5-10% 10-30% 0-5% 30-50% 50-70%

  9. Λ +h correlations AuAu (cosine fit)

  10. Width (Λ+h) 1.5<pT,trigger<3.0, 1.5<pT,asso<3.0 2.5<pT,trigger<4.0, 1.7<pT,asso<2.5 Gaussian fit Cosine fit

  11. Associated particle yields (Λ+h) 1.5<pT,trigger<3.0, 1.5<pT,asso<3.0 2.5<pT,trigger<4.0, 1.7<pT,asso<2.5 Gaussian fit Cosine fit

  12. AA/pp (Λ+h) 1.5<pT,trigger<3.0, 1.5<pT,asso<3.0 2.5<pT,trigger<4.0, 1.7<pT,asso<2.5 No pp reference Gaussian fit • Large AA/pp ratio for the same side • Trigger Bias? X N Wang, nucl-th/0405017 Cosine fit

  13. same and away side yields of different particle species

  14. Same side width of different particle species Anti Lambda Lambda K0 short

  15. PHENIX measurementfrom QM2004 SAME SIDE

  16. PHENIX measurementfrom QM2004 AWAY SIDE

  17. 1.5 GeV/c < pT,trig,pT,asso<3.0 GeV/c

  18. Summary: • We can measure identified particle correlations • For central collisions, large width(>π/2~1.6) of the back side indicates a momentum balance shape and collapse of the Jet structure.☺ • Same side AA/pp ratio appears to be large in the intermediate pT range Measurement of N could provide us information about how the jet get quenched inside the medium, what is the scare of particles interacted with the quenched jet. • Trigger particle species dependence: • comparable to PHENIX measurements • No significant particle species dependency • No strong centrality dependency, need further study on the systematic

  19. Backup

  20. Hh AA/pp ratio for G fit

  21. Momentum Balance measurement comparing to balancing over the large amount of particles by assuming α ~ 1.0

  22. 3.7 < pT trigger < 4.5 GeV/c 5.4 < pT trigger < 6.5 GeV/c 2.5 < pT associated < 3.7 GeV/c 2.5 < pT associated < 3.7 GeV/c 1/Ntrigger dN/d(∆Φ) 1/Ntrigger dN/d(∆Φ) ∆Φ (radians) ∆Φ (radians) 4.5 < pT trigger < 5.4 GeV/c 6.5 < PT trigger <10 GeV/c 2.5 < PT associated <3.7 GeV/c 2.5 < pT associated < 3.7 GeV/c 1/Ntrigger dN/d(∆Φ) 1/Ntrigger dN/d(∆Φ) ∆Φ (radians) ∆Φ (radians) Back side correlations between charged hadrons: Trigger PT Fig. 12 Same side and back side as function of Trigger PT same side is calculated by integrating the Gaussian component and the back side is calculated by integrated the cosine component. Notices that there is a clear back side signal for higher pT,triggervalues Fig. 13 Trigger PT In Fig.13 the Ccos fit values are compared to an estimate of the momentum conservation effect [6]. Fig. 11 Charged Hadrons correlations for different trigger PTrange Fitting Function:

  23. Hence αcan be measured by studying the statistical pT fluctuations of the back side jet cone compared to inclusive background

  24. Uncorrelated backgrounds Seems works pretty well!!

  25. L+h cos fit 1

  26. L+h vs. Anti-L+h (most central)

  27. L+h cut 2

  28. al+h cos fit

  29. K0 short +h fit

  30. h+h AA

  31. Hh fit

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