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The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid

The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid. An overview of findings at RHIC Richard Seto University of California, Riverside Helsinki, Finland April 27, 2006. In the Beginning…. what is “quark soup” like?. hadrons. quark-hadron QCD phase transition.

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The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid

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  1. The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid Anoverview of findings at RHIC Richard Seto University of California, Riverside Helsinki, Finland April 27, 2006

  2. In the Beginning… • what is “quark soup” like? hadrons quark-hadron QCD phase transition

  3. Phases T Quark Soup Tc Hadrons

  4. Transition – Sharp Crossover at RHIC That’s OK – 1st order for all practical purposes Sharp Crossover difference between S-B and lattice interactions (in hindsight) Lattice Calculations ~degrees of freedom T Tc Relativistic Heavy Ions RHIC Lattice Calculations: Tc = 170 ± 15% MeV ecritical ~ 0.6 GeV/fm3

  5. RHIC • Capable of colliding ~any nuclear species on ~any other species • Energy: • 500 GeV for p-p • 200 GeV for Au-Au(per N-N collision) • Design Luminosity • Au-Au: 2 x 1026 cm-2 s-1 • p-p : 2 x 1032 cm-2 s-1(polarized)

  6. RHIC’s Experiments STAR

  7. 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?) • DOF ~ “quasi-quarks” ???? • General picture is stable since ~ 2004 • More data since QM 2005 • More theory • A clearer view what is “quark soup” like?

  8. 100 Cross over (wanna be 1st order) 4 5 10 ~Energy Density (GeV/fm3) Partonic 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.)

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

  10. Using high pT particles aka “Jets” p+p Au+Au d+Au

  11. peripheral Au+Au d+Au Au+Au RAA =1 for “normal collissions” Direct γ π0 η What is the energy density? “Jet quenching” direct photons scale as Ncoll dAu hadrons scale as Ncoll periph AuAu π0 scale as Ncoll central π0suppressed hadron suppression shows quenching independent of identity of produced hadron AuAu 200 GeV • Calculations: • dNg/dy ~ 1000 • Wicks et al, nucl-th/0512076 • ε ~10-15 GeV/fm3 • εcritial ~0.6 GeV/fm3 Central AuAu

  12. Jet correlations in proton-proton reactions. Strong back-to-back peaks. Jet correlations in central Gold-Gold. Away side jet disappears for particles pT > 2 GeV Jet correlations in central Gold-Gold. Away side jet reappears for particles pT>200 MeV Leading hadrons Medium Jet on the “other” side? Thermalized partons pp AuAu Azimuthal Angular Correlations

  13. 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

  14. What about heavy quarks? (electrons from c and b) (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 Large Energy loss of partons  energy density far in excess of critical energy density • Charm high pT suppression ~ light hadrons!!! • Problem – difficult to reconcile with gluon radiative energy loss • theorists have to go back to the drawing board

  15. Hadronizationand Recombinationhints of the DOF reco

  16. Recombination and the baryon anomaly pbar/π varies with √sNN in Cu+Cu PHENIX Preliminary • Originally thought: particle production at “moderate” pTfrom mini-jet Fragmentation pbar/π- ratio CuCu central At ISR pbar/π- ~ 0.2 higher energy 200 GeV BUT Heavy ion Collisions pbar/π- ~0.7 Increasing with energy 22 GeV

  17. Explanation: Recombination – a hint at the DOF • Naively: recombine quasi-partons (“quasiquarks” – Gavai) • PT • baryons pT  3 pT • mesons pT  2 pT Mueller et al, Hwa et al, Ko et al +Thermal “quark” spectrum Large pbar/π This implies that we begin in a “quasi-partonic” thermal system

  18. Elliptic Flow (v2)Early Thermalizationand Recombination v2 v2

  19. z y x  Flow: A collective effect really? • Elliptic flow = v2 = 2nd fourier coefficient of momentum anisotropy • dn/d ~ 1 + 2v2(pT)cos (2 ) + ... • Initial spatial anisotropy converted into momentum anisotropy. • Efficiency of conversion depends on the properties of the medium.

  20. PHENIX Huovinen et al early thermalization? • If system free streams • spatial anisotropy is lost • v2 is not developed • detailed hydro calculations (QGP+mixed+RG, zero viscosity) • therm ~ 0.6 -1.0 fm/c •  ~15-25GeV/fm3 • (ref: crit ~0.6 GeV/fm3) (Teany et al, Huovinen et al)

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

  22. 2) Data from minimum bias Au+Au collisions at √sNN= 200 GeV PHENIX Preliminary (mT - m0)

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

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

  25. Hydro works in min-bias not as function of centrality initial cond? (Rafelski) Hydrodynamics (in the hadronic phase) and centrality

  26. 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? “constituent quarks”

  27. DOF and Baryon-Strangeness Correlations • different degrees of freedom introduce different correlations between conserved charges • assumption: conservation of charge @ hadronization local in rapidity • introduce baryon-number strangeness correlation: • system of particles: • connection to Lattice susceptibilities: QP-QGP: CBS=1 HG: CBS~ 2/3 BS-QGP: CBS~0.61 CBS: V. Koch, A. Majumder & J. Randrup, PRL95 182301 (2005) BS-QGP: E. Shuryak, I. Zahed,PRC70 021901 (2004);PRD70 054507 (2004)

  28. CBS & CQS: Lattice & Lessons • T>TC: CBS=1 • mesonic as well as baryonic bound-states ruled out via χBS and μB-derivatives thereof • Lattice confirms quasi-quark nature of flavor carriers in the deconfined phase Gavai, Majumder Gavai & Gupta, PRD 73, 14006, 2006

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

  30. 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

  31. data prefers charm flow for charm to flow interactions must be very strong Viscosity small Heavy quarks: Single electron v2 Greco, Ko, Rapp PLB 595 (2004) 202

  32. 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

  33. Los Angles Times – May 2005 WHAT?! Flow, Hydrodynamics, Viscosity, Perfect Fluds…. ? YUK! and String Theory

  34. Fluids: Ask Feynman ( from Feynman Lecture Vol II) • The subject of the flow of fluids, and particularly of water, fascinates everybody….we watch streams, waterfalls, and whirlpools, and we are fascinated by this substance which seems almost alive relative to solids. …. • The subject of the flow of fluids, and particularly of water, fascinates everybody…. Surely you’re joking Mr. Feynman

  35. [ ] Viscosity and the equation of fluid flow =density of fluid =potential (e.g. gravitational-think mgh) v=velocity of fluid element p=pressure Sheer Viscocity Bernoulli

  36. [ ] Non-ZERO Viscosity smoke ring diffuses smoke ring dissipates

  37. [ ] ZERO Viscosity does not diffuse smoke ring keeps its shape Viscosity dissipates momentum note: you actually need viscosity to get the smoke ring started

  38. Can we anyone calculate the viscosity?A primer on viscosity (Feynman again) the low-brow sheer force(stress) is: energy momentum stress tensor

  39. Using Maldecena 10-D string theory magici.e. AdS/CFT duality Gravity “QCD” “QCD” strong coupling N=4 supersymmetry ~ almost QCD “SYM” (OK the coupling constant doesn’t run, but I am interested in the strong coupling case, there are a bunch of extra particles so we will divide by the entropy to get rid of the extra DOF…) Gravity dual Policastro, Son, Starinets hep-th 0104066 “The key observation… is that the right hand side of the Kubo formula is known to be proportional to the classical absorption cross section of gravitons by black three-branes.” σ(0)=area of horizon

  40. finishing it up to get η/s Entropy black hole “branes” Entropy “QCD”  Area of black hole horizon Entropy black hole Bekenstetein, Hawking = σ(0)=area of horizon Kovtun, Son, Starinets hep-th 0405231

  41. viscocity~0, i.e. A Perfect Fluid? RHIC ~ 1? JPG, 30(2004) 1221 nitrogen viscosity bound? water helium T=1012 K • See “A Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231 • THE SHEAR VISCOSITY OF STRONGLY COUPLED N=4 SUPERSYMMETRIC YANG-MILLS PLASMA., G. Policastro, D.T. Son , A.O. Starinets, Phys.Rev.Lett.87:081601,2001 hep-th/0104066 lowest viscosity possible?

  42. When will we make 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 • Meanwhile – viscosity better become part of our ethos

  43. A strongly Interacting QGP? RHIC data: nearing hydrodynamic prediction with zero viscosity early thermalization strong coupling Old picture short screening length screening length q q weakly coupled QGP?

  44. A strongly Interacting QGP RHIC data: nearing hydrodynamic prediction with zero viscosity early thermalization strong coupling New picture Long screening length Long range correlations screening length q q sQGP New Lattice Data J//ψ stays together at > TC F. Karsch et al, Journal of Physics G 30 (2004) 887

  45. Deconfinement and Screening (a puzzle) Debye screening

  46. 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

  47. J/ suppression • Suppression similar in amount to SPS • consistent with screening+ regeneration sum regeneration screening

  48. 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

  49. <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

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