WWND 03/13/06 N Grau1 Jet Correlations from PHENIX Focus entirely on A+A collisions High-trigger p T correlations –Can we do jet tomography? Low-trigger.
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WWND 03/13/06 N Grau1 Jet Correlations from PHENIX Focus entirely on A+A collisions High-trigger p T correlations –Can we do jet tomography? Low-trigger p T correlations –Away-side shape modification –RP dependence An outlook –Direct -h correlations, non-photonic e-h correlations Nathan Grau, Columbia University, Nevis Labs For the PHENIX Collaboration
WWND 03/13/06 N Grau2 Constructing Jet Correlations Mixed events – corrects pair acceptance Hard scatteringResonance decays (rad) Elliptic flowTotal C( ) Sum over all events jets measured on a statistical basis
WWND 03/13/06 N Grau3 Jet Quenching Single particle suppression pattern persists to 20 GeV Moderate p T jets are suppressed Due to energy loss of partons in the medium Pedestal&flow subtracted
WWND 03/13/06 N Grau4 Away-Side Jet in Au+Au! C( ) strength ~ S/B of jets Red and blue lines are the uncertainty in v 2. Jets seen above the background for trigger >5 GeV/c and associated >2 GeV/c
WWND 03/13/06 N Grau5 Clear Away Side in Cu+Cu! Larger jet S/B in central Cu+Cu than central Au+Au v 2 modulation is smaller as well
WWND 03/13/06 N Grau6 Lack of Away-Side Broadening 8 < p T (trig) < 15 GeV/c Widths do not change between p+p and Au+Au?!? Trigger 5-10 GeV/c
WWND 03/13/06 N Grau7 Expected Broadening of Away Side Able to fit I AA from STAR. Red – gluons from energy loss. Black – scattering of parent partons I. Vitev hep-ph/0501255
WWND 03/13/06 N Grau8 Away Side Yield Suppression Away-side yield is suppressed?!? What mechanism can suppress yields without broadening them? –Tangential jets? –Punch through? 8 < p T (trig) < 15 GeV/c D. Magestro QM2005
WWND 03/13/06 N Grau9 Punch-through Events (I) Monte Carlo includes radial expansion reducing the effect of E ~ L 2 Non-zero probability to lose no energy Does the away side carry away any information from the interior of the collision zone? Production vertices of events with trigger > 8 GeV Red circles indicate an associated hadron (> 4 GeV) suffering no E-loss T. Renk hep-ph/0602045
WWND 03/13/06 N Grau10 Punch-through Events (II) Yield suppression sensitive to the probability of punch-through Lower p T pairs are apparently more sensitive to energy loss… Comparison of MC to STAR away-side yields.
WWND 03/13/06 N Grau11 Lower p T Correlations h-h Correlations in Au+Au (upper plots) –C( ) strength ~ jet S/B –Few % S/B at lowest pT Correlations. h-h Correlations with background subtracted (lower plots)
WWND 03/13/06 N Grau12 Different Colliding Systems and Energies Au+Au @ 200 GeV Cu+Cu @ 200 GeV Au+Au @ 62.4 GeV
WWND 03/13/06 N Grau13 Parameterize the Away-Side Shape trigg assoc D D Parameterize the away-side shape as a double Gaussian that are offset symmetrically around = by fit parameter D. Could be a “bent” jet or a mach/ Cherenkov cone
WWND 03/13/06 N Grau14 Au+Au Reaction Plane Dependence (I) Look at 4 th bin since it has the smallest v2. Dip exists at most central before substraction!
WWND 03/13/06 N Grau15 Au+Au Reaction Plane Dependence (II) Know v2 depending on triggers RP orientation. Shape independent of RP orientation
WWND 03/13/06 N Grau16 Au+Au Reaction Plane Dependence At Higher pT No hint of a volcano shape in any RP bin
WWND 03/13/06 N Grau17 For the future: Direct -h Direct photons not suppressed in the medium. Much less “trigger bias” i.e. less biased toward skin emission Photon measures jet energy measured away-side D(z) modification Hadrons PRL 94 232301 (2005)
WWND 03/13/06 N Grau18 Inclusive -h Correlations in Au+Au C( : 5-10 GeV/c h: 1-2 GeV/c Comparison with 0 triggered data necessary to extract direct photon correlations. : 5-10 GeV/c h: 3-5 GeV/c
WWND 03/13/06 N Grau19 Comparison of - and 0 - Triggered Widths Near-side widths are consistent between -triggered and 0 -triggered. Dominant inclusive photon correlation is decay from jet fragments
WWND 03/13/06 N Grau20 -h Near Side Yields PRL 94 232301 (2005) ~50% direct photons above 5 GeV/c in the most central. Also seen in -triggered near side yield ratio to 0 -triggered yield.
WWND 03/13/06 N Grau21 For the future: Non-Photonic e-h Use jet correlations to further understand heavy quark energy loss.
WWND 03/13/06 N Grau22 Summary and Conclusions High-p T triggered correlations show –Au+Au away-side that is not broadened –A suppressed yield consistent with punch-through jets. –What is learned from these correlations then? Low-p T triggered correlations show a strongly modified away- side shape –independent of system size and collision energy –Independent of trigger orientation to the RP Still left to do with current data –Further RP studies: Can we show E ~ L 2,L n ? –Direct -h: D(z) modification –e-h Correlations: Heavy quark energy loss