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Probing RHIC Matter with Di-Jets and Direct g -Jets in PHENIX

Explore insights into RHIC matter through Di-Jets and g-Jets via PHENIX at the ETD-HIC 2007 conference. Discover novel phenomena and medium responses seen at RHIC, including cone and ridge formations in jet-related events.

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Probing RHIC Matter with Di-Jets and Direct g -Jets in PHENIX

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  1. Thanks to the organizers! Probing RHIC Matter with Di-Jets and Direct g-Jets in PHENIX Justin Frantz SUNY Stony Brook ETD-HIC 2007 Montreal 07/17/07 Outline: 1) Cone and Ridge 2) “2+1” Correlations 3) Anticorrelations/Bkg Norm 4) g-jet in PHENIX

  2. jet h-h ridge Au+Au central @ 200 GeV a.u. Dh Df pTtrig=3-6 GeV/c, 1.5 GeV/c <pTassoc< pTtrig Jets in HI Collisions • Fast formation time of jet parton (determined by the initial state): traverses the medium • Fragmentation process non-peturbative similar timescale / energy scale physics • could also help us learn about Frag itself • Novel phenomena seen @ RHIC • Yield of hard hadrons suppressed • Jet associated event shapes affected: • Cone and Ridge STAR PHENIX Justin Frantz Montreal

  3. PHENIX w/ m Arm Cent Arm Acc m Arm h = 1.7-2.4 PHENIX Central Arm |h| < 0.35 What Can PHENIX Say About Ridge? • We see it in our nearside widths (and yields) • Effect only happens in this particular pT bin combos • Mixing of broader ridge Not much (so far)! 0-10% 20-40% 60-92% Justin Frantz Montreal

  4. PHENIX Focuses on the Cone Comprehensively • Studied: • System Size and Energy Dependence • pT (trig, partner) dependence • Baryon/Meson Dependence • RP Dependence • Definitely jet related? We can’t say for sure, but there is evidence: medium response PHENIX Final arXiv:0705.3238 [nucl-ex] Submitted to PRL Justin Frantz Montreal

  5. In PHENIX we found that the cone seems to have signature associated pT slope (independent of trigger pT) How about the ridge from STAR? Cone (S) Yield from Putchke’s RHIC Users ‘07 talk Cone pT Dependence <pTassoc>, pTtrig 3-4 GeV/c Nearside jet Bulk spectra arXiv:0705.3238 [nucl-ex] Justin Frantz Montreal

  6. In PHENIX we found that the cone seems to have signature associated pT slope (independent of trigger pT) How about the ridge from STAR? Trig pt independence too? Data thief-ing from the above plot for trig 4-5 GeV/c.... Cone (S) Yield from Putchke’s RHIC Users ‘07 talk Do the cone/ridgeslopes compare? <pTassoc>, pTtrig 3-4 GeV/c Nearside jet • I get truncated <pT> = 0.45 +/- 0.02 Bulk spectra WOW! note pTa ~ 1 vs pTa ~2 arXiv:0705.3238 [nucl-ex] Justin Frantz Montreal

  7. In PHENIX we found that the cone seems to have signature associated pT slope (independent of trigger pT) How about the ridge from STAR? Trig pt independence too? Data thief-ing from the above plot for trig 4-5 GeV/c.... from Putchke’s RHIC Users ‘07 talk Do the cone/ridgeslopes compare? <pTassoc>, pTtrig 3-4 GeV/c Nearside jet • I get truncated <pT> = 0.45 +/- 0.02 Ridge == Cone ! Bulk spectra WOW! note pTa ~ 1 vs pTa ~2 arXiv:0705.3238 [nucl-ex] Justin Frantz Montreal

  8. Baryon-Meson Make-up Comparison from J. Putchke’s RHIC Users talk • Cone @ low pt: B/M ~ same as inclusive • strong centrality dependence @ ~ 20%? - unique • Ridge: also like singles? Could use more precise statement singles B/M Ratio ~in cone STAR Statement: /K0S ratio ~ 1.0 in ridge (?) ~= singles Justin Frantz Montreal

  9. Another Ridge and Cone Connection? • Both also appear in (non-triggered) low pt/low pt correlations, ie bulk particle correlations • Also seen in extra correlation seen @ large Dh in bulk multiplicity: B. Srivastava QM06 (nucl-ex/0702054) • This is weird: Is it related? 0-5% pT > ~0.2 pT = 0.2-0.4 x 0.2-0.4 STAR same-sign (h-h) PHENIX Prelim opp-sign Justin Frantz Montreal

  10. Ridge and Cone Related? • There seems to be some concrete experimental evidence that the two phenomena are related • Ridge Associated pT spectra has ~identical slope as Cone component (both harder than bulk, by the same amount) • Bar./Meson ratio in both is ~close to bulk • Both phenomena may occur without a hard trigger • Both are harder than bulk, softer than jets, but seem to be jet related and thus medium response • This has been suggested by theory? • I couldn’t find a reference... Justin Frantz Montreal

  11. T1A1_T2 (also requires a T2) T2A1 (_T1 [right?] STAR Prelim Δf But what does p+p look like? PHENIX doesn’t have an exact answer just yet but... “2+1” Correlated (Jet) Yields • “Conditional” 2-Particle Yields (Projected 3-Particle) • Look at 2-particle Df we’re used to seeing... • but require a third hard particle (ie 3-p) • Select harder events, but same low particle pt... • or certain interesting orientations... • STAR “Back to Back” triggers Trigger1 (T1) T1: pT>5GeV/c T2: pT>4GeV/c A: pT>1.5GeV/c Associated (A1) Df Initial Conclusion: No Cone Hence No Modification Trigger2 (T2) Justin Frantz Montreal

  12. “Recycled” PHENIX 2+1 Analysis? • A similar ana in PHENIX (My QM06 poster): EEC • Trigger Photon (> 5 GeV/c) + 2 ch (~1 GeV) (inclusive g: dominated by meson decay) • “Energy” (EEC) wt’ing but w/ mp therefore ~= pT wt’ing (Due to steep spectra: makes ~no difference!) • “Pair” (triplet) by “Pair” correction Trig (Tg) g A2 T1 Df h+/- h+/- Justin Frantz Montreal

  13. PHENIX 2+1 Acceptance STAR Acc • Holes! (why we can’t use our Df12Df13 acc for “3-p” “Cone vs Deflected”) Only correct where Acc != 0 • EEC: all DfTg1However, like projecting out DfT1-T2 • Further kinematics bias (substantial?) towards Tg-1 back to back Legend --1 p DfTg-T1 = ftrig – f1 2+1 Ana DfT1-T2 No! Df = fT1 – fA1 Df12 = f1 – f2 Justin Frantz Montreal

  14. STAR Prelim 200 GeV p+p Results • p+p widths smaller? (broadening in Au?) • Kinematics? maybe. But widths should be dominated by lowest pT particle (STAR lowest pT = 1.5—should be a bit tighter to start with) • OK many caveats (non-bk to bk, kinematics, direct g contrib, etc...) • Anyway highlights need for p+p: More direct comparison underway in PHENIX Δf Justin Frantz Montreal

  15. Anti correlations? Review: Bkgd/Flow Subtraction • Subtraction: Underlying Event p+p p 0 Au+Au Au+Au Azimuthal Asym ~ v2 cos side view of Nuclear Collision Background Normalization ZYAM, ZYA1 Justin Frantz Montreal

  16. Issue w/ Normalization? (Cone) Mach Cone prediction (Gubser) <Bath Energy> subtracted • Point: As w/ Elliptic flow, particles are moved: thus wrt bulk, there can be “negative yield” • above plot shows example • Careful to keep in mind norm’ing • PHENIX Absolute method: • ~<Nt><Na> (same logic as √N++N– in di-lepton) • Difference w/ ZYAM are usually pretty small However, small h acc Justin Frantz Montreal

  17. Direct Photons - Jet Studies (?) • Prompt Direct Photons appear to be relatively unmodified • compare to hadrons which are suppressed by 80% w/ real p+p w/ fake “p+p” = pQCD hadrons Justin Frantz Montreal

  18. What can we learn from g-jet? • Cleaner determination of fragmentation modification ~ better constrain Eloss models IAA of Awayside yield of Direct g triggers F. Arleo hep-ph/0601075 IAA Renk.. hep-ph/0607166 w/ Eloss Trigger g don’t have same surface bias, thus eventually should constrain Eloss geometry Justin Frantz Montreal

  19. g-Jet Method Combine w/ next Use PHENIX Strength, EMCals, to detect photons! To cancel trigger efficiency Au+Au 200 GeV Run2 Final Rg In PHENIX Direct g Ana, we measure So using that knowledge, subtract Justin Frantz Montreal

  20. g-jet First Results • PHENIX Au+Au compared to p+p • Cu+Cu now available • Run 7 Statistics on Tape: ~3x • + use p0/decay g as associated: another x 2 • IAA should be possible + other improvements Justin Frantz Montreal

  21. Finalizing the Result: h decay (h-h) • Systematic from h contribution • PYTHIA difference in h/p frag surprising (more than mT) • Data measurement performed! • First h-h measurement @ RHIC Poster by Matt Nguyen today!!!! Daughter-h • Parent-h p+p Justin Frantz Montreal

  22. Run 5 p+p @ 200 GeV Statistical Subtraction Method p0 Direct g Recent Improvements in p+p w/ more stats, eta measured, multiple trigger bins • Slope difference ~ promising • Difference btw glue and quark jets? (plenty of other reasons of course) • Search for the 9/4 color factor (g vs q) in Eloss See poster by Matt Nguyen today!!!! Justin Frantz Montreal

  23. More on Tagging Quark Jets (to come) Under construction • More information in this direction: • Enlighten statement that “all baryons are from glue jets” Direct g pt 5-7 GeV/c pTa 1-2 GeV/c (prompt) Justin Frantz Montreal

  24. Final Remarks • “Cone” and “Ridge” unique RHIC phenomena! • There is some experimental evidence relating the two • Also relating them to jet phenomena • 2+1 Correlations offer another way to probe Jet Modification • p+p comparison important. • PHENIX p+p EEC result hints that Au+Au could be broadened? • Direct Photons have been important control to jet studies and are becoming that for jet-jet correlations • Eloss, Differentiating Eloss models, Geometric baises Justin Frantz Montreal

  25. Backup Justin Frantz Montreal

  26. Expo fit for slope error Justin Frantz Montreal

  27. EEC wt’ing vs normal Eg > 5 GeV pTmin > 1.0 Justin Frantz Montreal

  28. 2+1 Correlations - Results T1A1 (does not require a T2) T2A1 T1A1_T2 (also requires a T2) T2A1 Δf Δf Oana B.’s slide • Di-jet trigger - no modification on away-side • Surface dominated? • No energy loss for di-jets? STAR preliminary • Correlation of associates with: • T1 (also requires a T2) • T2 • Detailed shape of near- and away-side is the same STAR preliminary

  29. Other Systems and Energies • Energy Cutoff? • Pathlength/Volume Dependence? PHENIX Cu+Cu Au+Au 62.4 GeV 200 GeV Stony Brook Analysis (M. McCumber and JF) PHENIX Justin Frantz Montreal

  30. Scan: Shape Study • With these, do systematic study of shape • rms, kur (4th moment, non-gaussianness), peak location D Use Fit w/ allowing Away Peak Fit D PHENIX Fix D Away Width PHENIX Work In Progress Justin Frantz Montreal

  31. pT Dependence of shape • Most interesting feature, here again is constant D PHENIX PHENIX Final This is expected in some “Mach Cone” explanations, but inconsistent with initial color Cerenkov cone model... Justin Frantz Montreal

  32. pT Dep. of Shape and Yields Detailed study of pT dep. in central Au+Au PHENIX HS Ratio allows one to see where cone appears and “disappears” Justin Frantz Montreal

  33. pT Dependence of Yields • Calculate slope of the yields in each region • S region: harder than bulk • New interpretation: H region harder than shoulder until quenched—then dominated by tails of S or bulk • H region centrality dependence much like inclusive high pT suppression Inclusive h pT trig Centrality Justin Frantz Montreal

  34. 0-20% 2.5-4x1.6-2 GeV/c Cone Chemistry • Triggering on high pT and identify the associated hadrons • Cone shape observed baryons/mesons both (slight differences?) • B/M Ratio btw bulk and jet Justin Frantz Montreal

  35. Au+Au RP Dependence • Is there any “path-length”, direction (wrt RP) dependence? • Seems to be small, or hidden w/ RP reso. Justin Frantz Montreal

  36. Cu+Cu RP Dependence • Cu+Cu same Deccentricity in smaller Npart range (also range where cone could be distorting/disappearing) • Still no major difference seen • could still be RP resolution, even worse in Cu+Cu • New RP detector in Run 7 Au+Au PHENIX Work in Progress Stony Brook Analysis (M. McCumber and JF) Justin Frantz Montreal

  37. Conclusions so far about the Cone • Exists in ~all systems/ “hot medium” energies (including SPS!) and systems • shape independent of centrality • pT dependence is rich in physics: • Cone location is ~independent of pt • Slope of cone assoc. pt dependence of associated is like slightly harder than bulk, independent of trigger pt, ~centrality • not shown (WIP): cone yield at fix assoc pt, weakly rises w/ trigger pt, slower than p+p jet • B/M Ratio of Cone is lower than bulk, higher than pure jet These are consistent w/ some Mach Cone expectations Looking like jet-related medium excitation! Justin Frantz Montreal

  38. Jeon, Jalilian-Marian, Sarcevic nucl-th/0208012 Switching Gears (a little) • Picture of direct photons being unmodified not completely valid especially at lower pt • First gdirect porton from Fragmentation/ Bremstrahlung  from jets ie suppressed • However in addition, enhancement due to analagous mechanisms of the quenching jet-medium interactions • Multiple Scattering (Collisions) • Radiation Another type of Jet-Medium Interaction Signal! Justin Frantz Montreal

  39. Jet-Medium Photons • g-jet Conversion • Model: q jets traversing q/g bath convert (Kinematics: small u dominates: pg ≈ pq) First calc Fries, et. al./ more complete treatment w/ Turbide,Gale et. al. • Fragmentation (Brems.) g • Jet Eloss implies suppression of Frag g but Zakarov/others predict enhancement (New paper from E. Wang et. al.) also included by the above authors. w/o suppresion Justin Frantz Montreal

  40. Jet-medium Enhancement Tested… • At mid pT some enhancement may be possible, but current predictions are strongly disfavored • At high pT data favors standard suppression predictions, not enhancement Justin Frantz Montreal

  41. Direct Photon v2 • Jet suppression should cause same v2 for normal frag as for h • Enhancements should have negative v2 • Not seen in the data... Turbide, et.al PHENIX Preliminary PHENIX Preliminary Justin Frantz Montreal

  42. Implications/Discussion • Homework for theory: • Bremstrahlung enhancement must exist (in however small amount) if gluon radiative Eloss (GLV, BDPMS…) is present • can discrepancy be accounted for? Another constraint on radiative picture? • g-jet conversion seems reasonable given a QGP, where does it go wrong? (modified aS…) • Interpretation of the partonic medium? • Is there suppression in high pt gdirect? Still need more precision at high pT Justin Frantz Montreal

  43. m Arm h = 1.7-2.4 PHENIX Central Arm |h| < 0.35 PHENIX @ RHIC Forward/Bkwd Muon Arms Central Arm Central Arm Justin Frantz Montreal

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