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Physics Revealed at Intermediate p T

Physics Revealed at Intermediate p T. Rudolph C. Hwa University of Oregon. Quark Matter 2008 Jaipur, India February 6, 2008. low. intermediate. high. p T. 2. 6. hydro. no rigorous theoretical framework. pQCD. But that is where the action is, albeit experimental.

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Physics Revealed at Intermediate p T

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  1. Physics Revealed at Intermediate pT Rudolph C. Hwa University of Oregon Quark Matter 2008 Jaipur, India February 6, 2008

  2. low intermediate high pT 2 6 hydro no rigorous theoretical framework pQCD But that is where the action is, albeit experimental. What can we learn from the abundant data?

  3. Single particle distribution pT   B/M ~ 1 universal decrease with  (dAu) quark number scaling Huge p/ at =3.2 & breaking Two particle correlation data Near side Away side Ridge Jet Double bump Three particle correlation (1 or 2 triggers) Auto-correlation (no trigger) Overview

  4. Single particle distribution pT   B/M ~ 1 universal decrease with  (dAu) quark number scaling Huge p/ at =3.2 & breaking data Near side Away side Ridge Jet Double bump Three particle correlation (1 or 2 triggers) Auto-correlation (no trigger) Overview Two particle correlation

  5. pT  u, d, s g converted to q c,b,t primordial Reco Recombination at Intermediate pT S R J partons hadrons What partons? Medium effects

  6. pT Baryon/Meson ratios STAR 4 /K 3 2 1 0 in recombination/coalescence model (Reco) On the contrary, high B/M ratio is a signature of Reco. Baryons need less quark momenta than mesons. “Baryon anomaly” implies that fragmentation is normal.

  7. M: TT + TS + SS B: TTT + TTS + TSS + SSS M: then If B: 0.1 quark number scaling (QNS) Molnar & Voloshin, PRL91,(2003) 0.05 a property of naïve recombination  Elliptic flow

  8. M: TT + TS + SS B: TTT + TTS + TSS + SSS STAR, PRC75,054906(07)  K p  minbias RH&CBY,0801.2183 However, at larger KET QNS is broken, but hadronization is still by recombination

  9. Au+Au at 62.4 GeV xF = 0.8 xF = 0.9 xF = 1.0 BRAHMS, nucl-ex/0602018  TS TTT TT mainly p produced Few antiquarks at large  Shower partons are suppressed at the kinematical boundary Forward production

  10. Comments at the end, if asked. BRAHMS (preliminary)

  11. J+R     Properties of Ridge Yield Dependences on Npart, pT,trig, pT,assoc, trigger  B/M ratio in the ridge Correlation on the near side ridge RJet J Ridgeology STAR R J Putschke, QM06

  12. on pT,trig 2. STAR preliminary Putschke, QM06 pt,assoc. > 2 GeV Jet+Ridge () Jet () Jet) Ridges observed at any pT,trig Ridge yield 0 R as Npart 0  depends on medium Medium effect near surface 1. Dependence on Npart Ridge is correlated to jet production. Surface bias of jet  ridge is due to medium effect near the surface

  13. STAR (preliminary) A. Feng T s 20-60%, 3-4:1.5-2 RP |  1 Comments at the end, if asked. Ridge yield decreases with increasing s has more ridge yield than Mismatch of T and the direction of radial expansion. Ridge develops by radial flow near the jet axis 3. Dependence on trigger 

  14. Ridge Ridge is from thermal source enhanced by energy loss by semi-hard partons traversing the medium. 4.Dependence on pT,assoc Ridge is exponential in pT,assoc slope independent of pT,trig Putschke, QM06 STAR Exponential behavior implies thermal source. Yet Ridge is correlated to jet production; thermal does not mean no correlation.

  15. + pt,assoc. > 2 GeV 5. B/M ratio in the ridge STAR p Bielcikova, WWND07 Putschke, QM06 Au+Au 0-10%  K  2-4 Ridge hadrons are formed by recombination Large B/M

  16. Recombination of partons in the ridge associated particles SS trigger ST peak (J) TT ridge (R) These wings are useful to identify the Ridge Ridge is from enhanced thermal source caused by semi-hard scattering. Medium effect near surface coordinated with radial flow   But of interest below is mainly the  distribution.

  17. What are the consequences of Ridgeology? Jet correlation at low and intermediate pT Effect on single particle spectra Effect on elliptic flow

  18. J Peak is referred to as jet R ||<0.35 Does not see the ridge Not seeing the ridge does not mean that it is not there. Correlation in J is different from correlation in R 1. Jet correlation at intermediate pT PHENIX PHENIX, PLB 649,359(07) 2.5<pT,trig<4 GeV/c 1.8<pT,assoc<2.5

  19. PHENIX, PLB 649,359(07) Jet + Ridge Jet STAR preliminary STAR preliminary Not un-correlated. Ridge would not be there without semi-hard scattering. SS TS 0.35 How can intermediate-pt Jet yield be independent of centrality? TT

  20. STAR pt,assoc. > 2 GeV 2 p Putschke, QM06 R Au+Au 0-10% J   2 2.5<pT,trig<4.0 GeV/c PHENIX data cannot be properly understood without taking Ridge into account PHENIX 0712.3033

  21. Auto-correlationwithout triggers. 0.15<pt<2.0 GeV/c, ||<1.3, at 130 GeV STAR, PRC 73, 064907 (2006) 2. Effect of Ridge on single-particle spectra Semi-hard scattering at kT~2-3 GeV/c is pervasive. Ridges are present with or without triggers.

  22. TT TS (fragmentation) SS Bulk+Ridge Semi-hard partons generating ridge Fragments from hard partons T includes enhanced thermal partons --- Ridge

  23.  production: Au+Au   + anything (sss) s quark suppressed in shower Exposes the long exponential behavior in  production TTT TTS dN/ptdpt (log scale) uud sss pt How can we see better the TT component? Remove the TS and SS components, if possible.

  24. STAR How can it have correlated partners? --- the  puzzle. R only Prediction: there is no peak (J) in the  distribution --- only R Chiu & Hwa, PRC76,024904(2007)  spectrum is exponential (thermal) Resolution: Both  and its associated hadrons are in the Ridge.

  25. Initial configuration A semi-hard scattering near the surface gives rise to a jet, whose direction, on average, is normal to the surface.  If the semi-hard jets are soft enough, there are many of them, all restricted to || < .   = cos-1(b/2R) 3. Effect of Ridge on elliptic flow There is a layer of ridges at the surface without triggers.

  26. Use data on B(pT) and R(pT) Relate ridgeology to v2 Hwa, 0708.1508 In momentum space B bow tie region B+R

  27. Made no assumption about rapid thermalization. Elliptic flow at low pT v2 driven by Ridge

  28. Elliptic flow at intermediate pT v2 dominated by TS recombination Hwa & CB Yang, 0801.2183

  29. STAR, PRL 95, 152301 (05) Double-bump first observed by STAR PHENIX 0705.3238 & .3060 2D mild dependence of D on pt,assoc favors Is there any connection between the double bumps and ridge w/o peak(J)? Away-side correlation has been studied extensively --- experimentally and theoretically. Mach cone gluon radiation Cherenkov radiation deflected jets …

  30. Generated by semi-hard scattering Mach cone, deflected jet,--- due to recoil of semi-hard parton Large B/M ratio B/M ratio is also large. Due to recombination of enhanced thermal partons What is partonic structure of the Mach-shock-wave? Exponential pt,assoc Distribution in pt,assoc ? Possible relationship between ridge and bump (Renk, Jia) Near side Away side Ridge Bump

  31. Papers submitted to the session on: “Response of Medium to Jets” Experimental Theoretical Majumder C.Y.Wong Gavin Mizukawa, Hirano, Isse, Nara, Ohnishi Pantuev Lokhtin, Petrushanko, Snigirev, Sarycheva Levai, Barnafoldi, Fai Betz, Gyulassy, Rischke, Stoecker, Torrieri Molnar Asakawa, Mueller, Neufeld, Nonaka, Puppert Schenke, Dumitru, Nara, Strickland Bauchle Netrakanti (STAR) Wenger (PHOBOS) McCumber (PHENIX) Suarez (STAR) Feng (STAR) Adare (PHENIX) Barannikova (STAR) Catu (STAR) Daugherity (STAR) Pei (PHENIX) Haag (STAR) Szuba (NA49) G. Ma (STAR) Wang (STAR) Noferini (ALICE) Chetluru (UIC) Plenary session X Ulery Jia

  32. Those with existing codes can make extrapolations. Eskola et al (EKRT model) hard parton energy loss SS hadron SS or SSS recombination to form  or p. S S semi-hard partons On to LHC Many predictions made (see arXiv:0711.0974) Is there new physics that cannot be obtained by extrapolation? Density of semi-hard partons is high at LHC. p/>>1

  33. What is the bulk background at LHC? Since SS and SSS recombination of semi-hard partons are uncorrelated, they occur in mixed events. Thus they belong to the background. But those partons are not thermal,  not in hydro. So there is a mismatch between bg and hydro. Can Ridge be identified in association with a high pT trigger --- pT,trig > 20 GeV/c? The ridge may not stand out among the background that consists of TT, TS, SS, TTT, TTS, TSS, SSS hadrons. Physics at intermediate pT at LHC may be very different from that at RHIC ----- cannot be obtained by extrapolation.

  34. pT  S R J Physics revealed by phenomena observed at intermediate pT Summary soft & semi-hard partons

  35. QN scaling and breaking Exponential pT at large  Large B/M ratio Reco at LHC T S v2 Double bump Ridge Jet

  36. Backup slides

  37. Forward production p momenta degraded  survival probability “baryon stopping” Pions are suppressed due to the lack of antiquarks at large xi. Antiquarks at low xi are affected by the regeneration of that depends on .  ~0.75 Hwa & CBYang, PRC76,104901(2007)  should be larger less degradation more protons less increase of pions larger p/ ratio BRAHMS (preliminary) At large xF, proton can be formed by leading quarks from different nucleons. x can exceed 1

  38. STAR (preliminary) A. Feng T s 20-60%, 3-4:1.5-2 RP |  1 Ridge yield decreases with increasing s has more ridge yield than Mismatch of T and the direction of radial expansion. Ridge develops by radial flow near the jet axis 3. Dependence on trigger 

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