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What we have Learned and Challenges Ahead

What we have Learned and Challenges Ahead. An experimental overview of SQM 2006 Richard Seto UCR Strangeness in Quark Matter 2006 UCLA, March 25-31, 2006. . and more. What I will cover. Experimental overview (as requested)

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What we have Learned and Challenges Ahead

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  1. What we have Learned and Challenges Ahead An experimental overview of SQM 2006 Richard Seto UCR Strangeness in Quark Matter 2006 UCLA, March 25-31, 2006  and more

  2. What I will cover • Experimental overview (as requested) • For students – I will remind you of some of the arguments – ask if I don’t • I chose to be clear rather than comprehensive • Flavor/Particle ID plays a critical role • Primarily RHIC data from SQM 06 • SPS data – at the end • any misconceptions are mine • Selection of topics/data are mine • with apologies

  3. Topics I will not cover or will only briefly mention • Chiral Symmetry restoration (!) • Chemical equilibration • Strangeness enhancement –”the horn, the break” • nucleon structure • Fluctuations • Exotics • Astrophysics

  4. What we know: RHIC • What we know • System appears thermally and chemically equilibrated • This happens early <2 fm/c • Energy density high >10 GeV/fm3 • parton energy loss is large • viscosity/entropy, η/s is low ( conjecture ~1/4π?) • General picture is stable since ~ 2004 • More data since QM 2005 • More theory • A clearer view

  5. Busy days at RHIC p+p d+Au Au+Au Cu+Cu 22.4 GeV ? 62.4 GeV 130 GeV 200 GeV Run 1 - 3 Run 4 - 5 Run 6 (?) 4 experiments – BRAHMS, PHENIX, PHOBOS, STAR

  6. 100 Cross over (wanna be 1st order) 4 5 10 ~Energy Density (GeV/fm3) 0.1 1 10 0.1 ~Time (fm) A cartoon – the life history of the sQGP CGC “glasma” T. Lappi hard probes Thermalization Strongly Interacting Elliptic flow Recombination ~some reinteraction L. McLerran (modified by R.S.)

  7. Hadronization(so I can introduce recombination) reco

  8. Recombination and the baryon anomaly pbar/ varies with sNN in Cu+Cu • Originally thought: particle production at “moderate” pTfrom mini-jet Fragmentation PHENIX Preliminary pbar/- ratio CuCu central At ISR pbar/- ~ 0.2 BUT Heavy ion Collisions pbar/- ~0.7 Increasing with energy dave morrison

  9. Baryon/meson (pbar/p-) at √s = 200 GeV AuAu • Scales with Npart independent of system at h=0 and 3.2

  10. Explanation: Recombination • Naively: recombine quasi-partons (“quasiquarks” – Gavai) • PT • baryons pT  3 pT • mesons pT  2 pT • Problem: protons exhibit “jettiness” Mueller et al, Hwa et al, Ko et al +Thermal spectrum=Large pbar/π This implies that we begin in a “quasi-partonic” thermal system

  11. STAR Preliminary STAR Preliminary ReCo Model Modification(Hwa) Premise: The production of Φ and Ω particles is almost exclusively from thermal s quarks even out to 8 GeV/c Observables: The ratio of Ω/Φ yields should rise linearly with pT Mathew Lamont

  12. energy density“jet” energy loss hard probles energy loss

  13. Baryon Transport: How much energy available from the collision? RHIC data AuAu 200 • AGS->RHIC : Stopping -> Transparency • Rapidity Loss <dy>: 2±0.4: not linearly increase with ybeam • Energy loss <dE> per nucleon: 73±6 GeV • Available energy for excitation: ~3/4 of total energy~28 TeV JH Lee

  14. What is the energy density? “Jet quenching” AuAu 200 GeV direct photons scale as Ncoll p0suppressed h suppression shows quenching independent of identity of produced hadron Direct γ • Calculations: • dNg/dy ~ 1000 • Wicks et al, nucl-th/0512076 •  ~10-15 GeV/fm3 • critial ~0.6 GeV/fm3 π0 η yield in A+A/number of equivalent p+p collisions RAA = yield in p+p dave morrison

  15. Au+Au and Cu+Cu sNN = 200 GeV dave morrison

  16. Au+Au and Cu+Cu sNN = 200 GeV RAA Function of Npart independent of system dave morrison

  17. light (M.DjordjevicPRL 94 (2004)) How is the energy lost? • The sQGP has enormous stopping power • rifle bullet stopped in a tissue • Original idea – energy loss by gluon radiation • In 2001, Dokshitzer and Kharzeev showed “dead cone” effect  charm quark small energy loss

  18. What about heavy quarks? PHENIX (1) q_hat = 0 GeV2/fm (4) dNg / dy = 1000 (2) q_hat = 4 GeV2/fm (3) q_hat = 14 GeV2/fm Theory curves (1-3) from N. Armesto, et al., PRD 71, 054027 (4) from M. Djordjevic, M. Gyullasy, S.Wicks, PRL 94, 112301 • We see strong suppression even for heavy quark (charm). Alan Dion PHENIX

  19. STAR: Phys. Rev. Lett. 91 (2003) 172302 What about heavy quarks? STAR • RdAu is above/consistent with unity • RAA suppression up to ~0.6 in 40-80% • Suppression up to ~0.5 in 10-40% • Strong suppression up to ~0.2 in 0-5% centrality at high pT (4-8 GeV/c) • Charm high pT suppression is as strong as light hadrons!!! • Problem is – theorists have to go back to the drawing board (Steffen?) Haibin Zhang

  20. Elliptic Flow (v2)ViscosityRecombination v2 v2

  21. PHENIX Huovinen et al Previous Results • If system free streams • spatial anisotropy is lost • v2 is not developed • Hence • Early thermalization • low viscosity • detailed hydro calculations (QGP+mixed+RG, zero viscosity) • therm ~ 0.6 -1.0 fm/c • ~15-25GeV/fm3 • (ref: cold matter 0.16 GeV/fm3) (Teany et al, Huovinen et al)

  22. Recombination and v21) Three regions of v2 v2 STAR preliminary v2 Maya Shimomura, SQM’06 from partonic AND hadronic quark number dependent from partonic AND hadronic mass dependent geometry-driven absorption anisotropy geometry-driven momentum anisotropy

  23. 2) Data from minimum bias Au+Au collisions at sNN= 200 GeV PHENIX Preliminary (mT - m0) dave morrison

  24. 3) A recombination test rescale by quark number Au+Au collisions at sNN= 200 GeV PHENIX Preliminary Recombination works! (mT - m0) dave morrison

  25. v2 of strange hadrons from STAR • Mass ordering observed at lower pT fit by hydro in hadronic phase • v2 saturates for pT > 3 GeV/c • Clear baryon/meson difference at intermediate to high pT observed • New, high statistics measurement shows deviation from ideal scaling . Mesons above 1. baryons below 1 Mathew Lamont Talk: M. Oldenburg, Poster:Yan Lu

  26. v2 of strange hadrons from STAR • Mass ordering observed at lower pT fit by hydro in hadronic phase • v2 saturates for pT > 3 GeV/c • Clear baryon/meson difference at intermediate to high pT observed • New, high statistics measurement shows deviation from ideal scaling . Mesons above 1. baryons below 1

  27. v2 of strange hadrons from STAR • Mass ordering observed at lower pT fit by hydro in hadronic phase • v2 saturates for pT > 3 GeV/c • Clear baryon/meson difference at intermediate to high pT observed • New, high statistics measurement shows deviation from ideal scaling . Mesons above 1. baryons below 1 The same scaling behaviour is observed in62 GeV data

  28. The  - a test • the  • mass ~ proton • quarks - meson V2 behaves as recombination says it should Sarah. Blythe ALL hadrons seem to obey quark number scaling!

  29. Hydro works in min-bias not as function of centrality initial cond? (Rafelski) Hydrodynamics and centrality Marcus. Oldenburg

  30. recombination and number of quark scaling works for centrality dependence Recombination and centrality? peripheral mid-central central Recombination works well. WHY? What is recombining?? DOF??? A quasi-quark Plasma? Marcus Oldenburg

  31. v2 heavy quarks and viscosity The stone in the river or the concrete canoe University of Wisconsin Badgers engineer third-straight concrete canoe title

  32. Flow, viscosity, and strong coupling • Conversion of spatial anisotropy to momentum anisotropy depends on viscosity • Same phenomena observed in gases of strongly interacting atoms (Li6) M. Gehm, et alScience 298 2179 (2002) strongly coupled viscosity~0 weakly coupled finite viscosity The RHIC fluid behaves like this, viscocity~0 now throw a stone in there

  33. data prefers charm flow addition of bottom to model improves fit at higher pt for charm to flow interactions must be very strong Viscosity small Heavy quarks: Single electron v2 Greco, Ko, Rapp PLB 595 (2004) 202 Shingo Sakai, SQM’06

  34. pT Hendrik, Greco, Rapp nucl-th/0508055 w.o. B meson (c flow) w. B meson (c,b flow) • based on quark coalescence model • c, b reso ; c,b get v2 by elastic scat. in QGP B meson contribution heavy quark electron v2 • B electron v2 reduces heavy quark electron v2 @ high pT • We need to directly measure D’s and B’s Shingo Sakai

  35. Comment on a quantitative measure of the viscosity • Upgrades -microvertex detectors - to both STAR and PHENIX will allow measurement of D and B mesons directly • Theory – will take a while – (Steffen?) • Meanwhile – viscosity better become part of our ethos

  36. Back to the beginningHow does the sQGP get started? a candidate - the CGC CGC

  37. CGC • prediction: suppression in dAu collisions • forward • central for all particles Central Midcentral HongyanYang BRAHMS

  38. What about charm? • prompt muons charm(bottom) are suppressed in dAu CGC Xiaorong Wang, SQM 2006 Au South Arm d Au d North Arm

  39. Initial Temperature Tinitial

  40. Compare to NLO pQCD • L.E.Gordon and W. Vogelsang • Phys. Rev. D48, 3136 (1993) • excess above pQCD Thermal photons - The Spectrum Compare to thermal model • D. d’Enterria, D. Perresounko • nucl-th/0503054 2+1 hydro T0ave=360 MeV(T0max=570 MeV) t0=0.15 fm/c • data above thermal at high pT Compare to thermal + pQCD • data consistent with thermal + pQCD The Future – PHENIX- HBD

  41. What have we learned • Jet quenching • Charm quark energy loss, pretty well established • Viscosity • Charm flows – further evidence that viscosity is small (interactions are strong) • Recombination • baryon to meson ratio seems to obey recombination scaling • All particles seem seem to obey v2 recombination scaling. [, ;Ω] • Some evidence for fine structure • Evidence for quasi-partons from Recombination/Lattice • CGC • indications of charm suppression in dAu collisions at forward rapidity RHIC is now studying a state of matter clearly above the transition Question: So where is it? Deconfinement? Is there a critical point?

  42. Deconfinement and Screening (a puzzle) Debye screening

  43. A Theory update which bothers experimentalists • J/  “melts” at T>1.5 TC (Agnes Mocsy, Peter Petereczky) • “Screening likely not responsible for quarkonia suppression” (Agnes Mocsy, Peter Petereczky) • “You have to use the right potential” (CY Wong) • Does quarkonia suppression tell us anything about deconfinement!??? • Who is right?!! an experimentalist

  44. J/ suppression sum regeneration screening

  45. 1.2<|y|<2.4 |y|<0.35 Aside: RAA of J/ in Au+Au/Cu+Cu • Most things depend on Npart independent of species • Why is J/ at y=0 different for Cu and Au? Corona? • Might help in understanding suppression mechanism Constrained by d+Au Andrew Glenn

  46. <pT2> as a function of Ncol Au+Au = RED Cu+Cu = BLUE Dashed: without recombination Solid: includes recombination Recombination model matches better to the data... nucl-th/0505055 Andrew Glenn

  47. No recombination All recombination Recombination predictions vs rapidity • Recombination ( Thews et al., nucl-th/0505055 ) predicts a narrower rapidity distribution with an increasing Npart. • Going from p+p to the most central Au+Au : no significant change seen in the shape of the rapidity distribution. Andry R

  48. RAA vs. pT in Au+Au/Cu+Cu • Suppression of J/Y yield at low pT in both Au+Au and Cu+Cu. • High pT J/Y escape the medium? Leakage effect? [Phys. Lett. B 607 (2005)] • Might one expect “pile up” at low pT for recombination+energy loss? Andrew Glenn

  49. The critical point? connecting to lower energies

  50. Survival probability corrected for normal absorption Karsch, Kharzeev, Satz energy density Connecting to lower energies • unique things (so far) • ρ broadening • break in Inverse slopes @ √sNN~5 • AGS/SPS/RHIC similarities • strangeness enhancement • J/psi suppression • Ways to look • wait for GSI • wait for JPARK • RHIC ~ 5GeV

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