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Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX

Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX. Chris Pinkenburg for the PHENIX collaboration. STAR-Jet event in pp. STAR Au+Au central. PHENIX Au+Au central. High p T particle. Au+Au. Jets in Heavy Ion Collisions. High p T particle. p+p. Jets

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Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX

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  1. Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX Chris Pinkenburg for the PHENIX collaboration ICHEP 2010

  2. STAR-Jet event in pp STAR Au+Au central PHENIX Au+Au central High pT particle Au+Au Jets in Heavy Ion Collisions High pT particle p+p • Jets • directly related to partons • Difficult experimentally • (e.g. dependence on jet algorithm, • fake jets due to underlying event • in HI collisions) • High pt particles are a proxy for a jet • Experimentally easier to handle • Correlations are simple and • rather straightforward • more difficult to relate to partons ICHEP 2010 per unit velocity || to beam

  3. The PHENIX Detector Event Characterization • Vertex,centrality, reaction plane: Zdc, Bbc, Mpc, Rxnp h± h p0 • Single Particle reconstruction • Charged Particle Tracking: DC,PC1,RICH,PC3 clean up to pt5GeV/c • Photon and p0 Reconstruction: PbSc, PbGl, PC3 easy p0 id up to pt=20GeV/c • What makes PHENIX suitable for jet • measurements despite small acceptance? • High granularity emc (>19000 towers) • with trigger capability • High speed daq (> 5kHz) and trigger for • rare probes ICHEP 2010

  4. Trigger Particle: π0 (4-9 GeV/c), Associated Particle: h± (0.5-7 GeV/c) ptT > 7 GeV/c Back-to-back peaks for all measured associated pT No evidence for jet broadening Away-side suppression at large associated pT PRL 104, 252301 (2010) Two Particle Correlations Broad range of trigger ptT ICHEP 2010

  5. Phys. Rev. Lett. 104, 252301 (2010) No away side broadening at pt>5GeV/c head IAA > RAA ZOWW H.Zhang, J.Owens, E.Wang, X-N.Wang PRL 103, 032302 (2009) Follows data reasonably well (describes also RAA of p0 and IAA of -h) Uses a simple spherical geometry away Away Side IAA ICHEP 2010

  6. Two particle correlations with respect to the reaction plane ICHEP 2010

  7. Insignificant near-side trend Falling away-side trend We seem to have some path length dependence Per Trigger Yield Ratios ICHEP 2010

  8. X.N. Wang, Z. Huang PRC55 (1997) 3047-3061 Measurements with Photon Tagged Jets QCD Compton qg  q  penetrates medium Direct γ RAA1  no medium effect γenergy ≈ jet energy Measured: IAA = YAA/Ypp≈DAA(z)/Dpp(z) ICHEP 2010

  9. γ-h Df Correlation Measured statistically Small near-side yield (fragmentation photons) ICHEP 2010

  10. IAA,RAA Comparison Away-side -h: suppression similar to both RAA and IAA similar path as RAA quark jet dominated ICHEP 2010

  11. Towards the Fragmentation Function Away-side -h: fragmentation function somewhat steeper than p+p (only 1.3σ significance) bpp consistent with quark fragmentation (b=8) dN/dzT =Ne−bzT bAuAu= 9.49 ± 1.37 bpp= 6.89 ± 0.64 ICHEP 2010

  12. CuCu Rejected Accepted Improved background suppression over kT or SISCone algorithm Y. Lai, arXiv:0806.1499 PHENIX Jet Reconstruction: Gaussian Filter pp ICHEP 2010

  13. pp Jet Spectrum Follows pQCD Extends out to pt=60GeV/c ICHEP 2010

  14. Unfolded Cu+Cu RAA We see significant Jet suppression in CuCu Jet RAA is comparable to p0 RAA ICHEP 2010

  15. Conclusion • We see significant jet suppression in CuCu • The pp jet spectrum extends to pt=60GeV/c • Correlations with high pt particles provide a wealth of additional information which are consistent with our jet measurements • This years silicon vertex upgrade will enable heavy flavor tagging in the upcoming run ICHEP 2010

  16. Future PHENIX (Super-PHENIX, sPhenix, Sphnx..?) Counts per 2.5 GeV bin in 50B AuAu Events NLO pQCD (W. Vogelsang) CTEQ6M5, DSS FF pp @ 200 GeV |h|<1.0 q,g jets Direct g Fragmentation g p0(assume RAA = 0.2) GEANT4: Q-Pythia Dijet Event p0 Photons Jets Coverage 2,  = 1 Build on existing svtx, fvtx RHIC II Luminosity 50 bio events/year sampled Hi speed daq (25bio events/year on tape) ICHEP 2010

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