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PHENIX Measurement on High p T h-h and g -h Azimuthal Correlations

PHENIX Measurement on High p T h-h and g -h Azimuthal Correlations. Jiamin Jin for the PHENIX collaboration Quark Matter 2006, Shanghai Nov. 18, 2006. Outline. Motivation High p T p 0 -h correlation results (Cu+Cu/p+p) Width and Yield Moving on to direct g -h Method

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PHENIX Measurement on High p T h-h and g -h Azimuthal Correlations

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  1. PHENIX Measurement on High pT h-h and g-h Azimuthal Correlations Jiamin Jin for the PHENIX collaboration Quark Matter 2006, Shanghai Nov. 18, 2006

  2. Outline • Motivation • High pT p0-h correlation results (Cu+Cu/p+p) • Width and Yield • Moving on to direct g-h • Method • Results in Au+Au, how does it compare to p+p? • Conclusions

  3. nucl-ex/0510023 T Motivation • High pT suppression • Pattern persists up to 20GeV/c • Integral quantity, limited sensitivity to medium properties • more differential observables needed, angular correlations! • How are inclusive spectra and jet associated yields related? • How is energy loss reflected in away side suppression? • Near side energy loss?

  4. Construct CF, yield, various jet variables…  Correlation Function (CF) Trigger Assoc Df Mixed events -- correct PHENIX pair acceptance  

  5. CF(Df) [A.U.] 1/NtrigdN/dDf p0: 5-10GeV/c PHENIX Preliminary p0: 5-10GeV/c PHENIX Preliminary p0-h CF and yield: Cu+Cu vs p+p 0-20% Cu+Cu p+p • Per trigger Yield • away side peak seen in both systems • CF strength: ~ jet S/B, p+p > Cu+Cu • lines indicate flow modulated background. No flow in p+p

  6. p0: 5-10GeV/c Near side jet shape: width Gauss width • Consistent Gauss width between Cu+Cu and p+p

  7. Near side jet shape: Pout red: Cu+Cu black: p+p Pout • Enhancement of Pout tail in Cu+Cu (large Df), near side modified

  8. Away side jet shape p0: 5-10GeV/c Gauss width • Within errors, away side Gauss width shows no centrality dependence • No broadening from p+p to Cu+Cu @ high trigger pT!

  9. IAA: modification of yields Red: near side Blue: away side IAA = Yield(Cu+Cu) Yield(p+p) E • Near side IAA ~ unity • Away side IAA suppression ~0.6 at xE>0.4

  10. Integrated IAA(0.4<xE<1.0) similar with RAA! • more suppression, as peripheral  central

  11. Integrated IAA(0.4<xE<1.0) similar with RAA! • more suppression, as peripheral  central • similar to p0 RAA values!

  12. g g p0 g g hot dense medium Moving on to the next stage: direct g-h • Normal dijet (po-h): • Trigger bias: Ep < Ejet,, <z>~0.75 • Possible surface bias • Direct g tagged jet: • No fragmentation: Eg ~ Ejet • No strong interaction, sensitive to the whole medium Proposed in hep-ph/9605213 ~10 years ago

  13. g g p0 PHENIX Preliminary Moving on to the next stage: direct g-h • Normal dijet (po-h): • Trigger bias: Ep < Ejet,, <z>~0.75 • Possible surface bias • Direct g tagged jet: • No fragmentation: Eg ~ Ejet • No strong interaction, sensitive to the whole medium • Inclusive g-h Yield • Trigger photon is a mixture of direct and hadron-decay photon • Need to subtract decay part Proposed in hep-ph/9605213 ~10 years ago g g hot dense medium

  14. Method • Construct inclusive g-h yield • Construct decay g-h yield via: • Pair by pair weighted summation • convolutes all p0-h pair contributions from higher pT • Weight reflects probability from kinematics for p0 at given pT to decay into photon in given pT range • Subtraction via: 

  15. Method • Construct inclusive g-h yield • Construct decay g-h yield via: • Pair by pair weighted summation • convolutes all p0-h pair contributions from higher pT • Weight reflects probability from kinematics for p0 at given pT to decay into photon in given pT range • Subtraction via:    p+p # inclusive g #decay g R=

  16. PHENIX Preliminary PHENIX Preliminary • data • PYTHIA First direct g-h yield in p+p, cmp with PYTHIA! p+p: important baseline measurement! PYTHIA 6.1 kT = 2.5 GeV • A nice confirmation of our method

  17. First direct g-h yield in Au+Au! Au+Au: study medium induced modification! 1/NtrigdN/dDf 1/NtrigdN/dDf Df(rad) Df(rad) • v2 modulated bkgd for inclusive/decay g subtracted from each corr. fn under ZYAM assumption (v2 from from single g/p measurements) • Near side yield consistent with 0 • small fragmentation photon yield • Away side yield also small, suppressed!?

  18. Comparison btw Au+Au and p+p Black: Au+Au Red: p+p 1/NtrigdN/dDf 1/NtrigdN/dDf Df(rad) Df(rad) • Hint of away side modification in AuAu!

  19. 1/NtrigdN/dDf Df(rad) Comparison btw Au+Au and p+p Black: Au+Au Red: p+p

  20. Away side integrated yield • trigger g pT dependence • assoc. h pT dependence • centrality dependence + pp • p+p shows a systematic trend of having higher yields in the • away side than Au+Au!

  21. Conclusions • Precision measurements of high pT dijets in Cu+Cu/p+p collisions • Near side modification visible in Pout distribution. • Away side yield suppressed; shape, peak width unchanged • Away side IAA quantitatively consistent with RAA • First measurements of high pT direct g-h yields in Au+Au/p+p collisions • Near side yield ~ 0 • Hint of suppression of away side jets in Au+Au • Need more statistics to make conclusive statement • Upcoming Au+Au run

  22. Some related posters 41 Nathan GrauEvolution of the Away-side Jet Shape and Yield From π0-h± Correlations in sqrt(sNN) = 200 GeV Au+Au collisions 43 Jiangyong JiaStudy of the medium modification of the away side jet using π0-hadron correlation in AuAu/CuCu collisions in PHENIX 37 Matthew NguyenPhoton-hadron two particle correlations in sqrt(sNN) = 200GeV Au+Au collisions with the PHENIX detector 48 Hua Pei Medium Effect on Jet Correlations in Cu+Cu Collisions at sqrt(sNN) = 200 GeV at RHIC-PHENIX

  23. PHENIX people

  24. Backup slides

  25. Per trigger yield suppressed trigger direct g away side jet

  26. Cu+Cu, trigger 5-10GeV/c, 0-20% p+p, trigger 5-10GeV/c p0-h CF and yield: Cu+Cu vs p+p • CF strength: ~ jet S/B, pp > CuCu • away side peak seen above background in all systems

  27. Cu+Cu, trigger 5-10GeV/c, 0-20% p+p, trigger 5-10GeV/c p0-h CF and yield: Cu+Cu vs p+p • CF strength: ~ jet S/B, pp > CuCu • away side peak seen above background in all systems • away side jet shape – pp: normal gaussian peak, CuCu: modified • - No dip, but extra yield ~ Df=2, conical structure?

  28. Yield/IAA: for different centralities Red: near side Blue: away side IAA = Yield(Cu+Cu) Yield(p+p) • Near side IAA ~ unity • Away side yield suppressed! more suppression in central

  29. Consistent widthwithin Cu+Cu & p+p! Near side Away side • Near side widtht decreases with pT • Away side gauss width no centrality dependence

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