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

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

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? nucl-ex/0510023 T

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

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

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

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

Away side jet shape Gauss width 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!

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

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

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

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 hot dense medium p0 g

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 p0 g g g hot dense medium PHENIX Preliminary

  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:  

   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=

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

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!?

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!

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

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!

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

Some related posters 41 Nathan Grau Evolution of the Away-side Jet Shape and Yield From π0-h± Correlations in sqrt(sNN) = 200 GeV Au+Au collisions 43 Jiangyong Jia Study of the medium modification of the away side jet using π0-hadron correlation in AuAu/CuCu collisions in PHENIX 37 Matthew Nguyen Photon-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

PHENIX people

Backup slides

Per trigger yield suppressed trigger direct g away side jet

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

p0-h CF and yield: Cu+Cu vs p+p p+p, trigger 5-10GeV/c Cu+Cu, trigger 5-10GeV/c, 0-20% 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?

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

Consistent width within Cu+Cu & p+p! Near side Away side Near side widtht decreases with pT Away side gauss width no centrality dependence