1 Future experiments in Relativistic Heavy Ion Physics Rene Bellwied Wayne State University Strangeness in Quark Matter SQM June Levoca, Slovakia

2 To limit the scope a little bit… To me SQM is the Quark Matter of Identified Produced Particle Measurements, preferably with s,c,b content. The scope of this year’s SQM was probably too expanded. SQM should not be a mini-QM. I will focus on flavor dependent measurements I will try to review: –The lessons from RHIC –The low energy running at RHIC and the FAIR programme –RHIC and its future accelerator and detector capabilities (RHIC-II) –The LHC programme

3 Lessons from RHIC: The Quark Soup liquid ? liquid plasma gas Hirano, Gyulassy (2006)

4 From light to heavy, from soft to hard participant scaling for light quark hadrons (soft production) binary scaling for heavy flavor quark hadrons (hard production) strangeness is not well understood (canonical suppression in pp ?) PHENIX D-mesons up, down strange charm

5 s-quarks are formed primordial Scaling according to quark content? u, d – scale with N part s,c,b – scale with N bin p – N part K 0 s – 1/2*N part + 1/2*N bin  – 2/3*N part + 1/3*N bin  – 1/3*N part + 2/3*N bin  – N bin  – N bin D – N bin Primordially produced strange quarks have to recombine with ‘thermal’ u,d quarks (thermal-shower picture ?) Normalized to central data H.Caines, SQM 2004

6 The medium consists of constituent quarks ? baryons mesons

7 Nuclear Modification Factor R cp 0-5% 40-60% 0-5% 60-80% √s NN =200 GeV Baryon and meson suppression sets in at the same quark p T. √s NN =200 GeV Strange R CP signals range of recombination model relevance Recombination scaling can be applied to R CP as well as v2

8 Particles are produced differently Partons have different current & constituent quark mass up, down strange charm Production scaling is different but v 2 is the same !! and R CP is the same !!

9 χ 2 minimum result D->e 2σ 4σ 1σ charm flows like light quarks. An amazing result.. strong elliptic flow of electrons from D meson decays → v 2 D > 0 v 2 c of charm quarks? recombination Ansatz: (Lin & Molnar, PRC 68 (2003) ) universal v 2 (p T ) for all quarks simultaneous fit to , K, e v 2 (p T ) a = 1 b = 0.96  2 /ndf: 22/27

10..which leads to a dramatic conclusion (  /s)…. Simultaneous description of STAR & PHENIX R(AA) and PHENIX v2 for charm. (Rapp & Van Hees, PRC 71, 2005) AdS/CFT ==  /s ~ 1/4  ~ 0.08 pQCD calculation of D (2  t)~6 (Teaney & Moore, PRC 71, 2005) ==  /s~1 transport models require –small heavy quark relaxation time –small diffusion coefficient D HQ x (2  T) ~ 4-6 –this value constrains the ratio viscosity/entropy  /s ~ (1.3 – 2) / 4  consistent with light hadron v 2 analysis & p T fluctuation analysis (STAR) …but what does it mean for the partonic degrees of freedom ?

11 Interlude: what do we know right now ? The degree of freedom for light quark particles seems to be a constituent quark (or a quasi-particle..). It is not massless in the strictest sense, but the ‘mass’ is the same for u,d,s quarks. Deconfinement, not necessarily chiral symmetry restoration These degrees of freedom seem to recombine in partonic medium to form hadrons. This is distinctly different from jet fragmentation. The strange quark seems to be produced primordially, whereas the light quarks a largely ‘thermal’. Effect should reduce at LHC, if hadronization occurs at same T (canonical suppression melts away (R. Stock)) Interesting test: the charm with a bare quark mass of 1300 MeV. It is definitely produced primordially but it also has a larger ‘thermal’ or ‘interaction’ mass. In other words it is a heavier quasi-particle. How can it show the same flow and the same nuclear suppression ?

12 The D-meson issues FONLL prediction STAR d+Au (MinBias ) STAR Cu+Cu (MinBias) STAR Au+Au (MinBias) PHENIX Au+Au (MinBias) PHENIX p+p (MinBias +  trigger) pp M. Floris (NA60), this conference: NA60 & NA50 is also several times above FONLL

13 The problem: semi-leptonic decay Kinematic smearing B- vs. D- contribution

14 Resolving heavy flavor experimental issues with better statistics at LHC energies and better detectors at RHIC-II Discrepancy between PHENIX and STAR in semi-leptonic D-meson measurements, even in pp Resolving B- and D-mesons through direct reconstruction of hadronic decay channels

15 The solution:  vertex detectors at RHIC and LHC HFT in STAR (2011 ?) VTX in PHENIX (2010 ?) IST in ALICE (2008) In addition (ALICE,CMS): B → J/  →  or ee  c,  b ?

16 Lower energies – the search for the critical point. Two dedicated programs: RHIC (2010) – bulk probes FAIR-CBM (2014++) – rare probes

17 The Quark Soup – when is it formed ? liquid ? liquid plasma gas CP ? sQGP ? RHIC FAIR 1.) is there a 1 st order phase transition at FAIR energies ? Is there a critical point ? 2.) is chiral symmetry restored at the critical point ? 3.) are the degrees of freedom different in the sQGP and at the critical point ? 4.) is there a QGP at the SPS ?

18 Location of the critical point Ejiri, et.al Taylor Expansion Fodor, Katz 2001 Lattice Re-weighting Gavai, Gupta 2005  B Lower Limit  B √s NN ——————————————————— 180 MeV25 GeV 420 MeV7.5 GeV 725 MeV4.5 GeV ———————————————————

19 Achievable Key RHIC Low Energy Measurements yields and particle ratios yields and particle ratios  T and  B identified particle elliptic flow v 2 identified particle elliptic flow v 2  collapse of proton flow? K/ , p/ ,  p T  fluctuations K/ , p/ ,  p T  fluctuations  the critical point signal scale dependence of fluctuations scale dependence of fluctuations  source of the signal v 2 fluctuations v 2 fluctuations  promising new frontier?

20 Major upgrade: 2  TOF for STAR Key detector for measurements of K/  ratio event-by-event, K/  fluctuations, and enhanced hadronic resonance reconstruction sensitivity at low and high p T (MRPC) Multi Resistive Plate Counter Tray Array

21 Onset of chiral symmetry restoration at high  B  in-medium modifications of hadrons ( , ,   e + e - (μ + μ - ), D) Deconfinement phase transition at high  B  excitation function and flow of strangeness (K, , , ,  )  excitation function and flow of charm (J/ψ, ψ', D 0, D ,  c )  sequential melting of J/ψ and ψ', charmonium suppression The equation-of-state at high  B  collective flow of hadrons  particle production at threshold energies (open charm) QCD critical endpoint  excitation function of event-by-event fluctuations (K/π,...) CBM – physics topics and observables

22 C. Blume et al., nucl-ex/ Decrease of baryon-chemical potential: transition from baryon-dominated to meson-dominated matter ? Low energy run at RHIC: remeasurement of K/π (incl. e-by-e) CBM: Excitation function of multistrange particle production and propagation (collective flow) Strangeness production at critical point ?

23 from Tony Frawley RHIC Users mtg. at LHC: (10-50) x  ~10% of L 25% running time 10 weeks CBM Au+Au 25 AGeV RHIC-II, LHC, CBM annual yields

Nambu model (Fujii et al., hep-ph/ ) CP and the chiral transition Massive Scalar Chiral transition m q =0 Critical point m q >0 ScalarVector (Baryon-density)‏ T<T c T>T c chiral symmetry restoration might decouple from critical point !

25 The Quark Soup – when does it vaporize ? liquid ? liquid plasma gas wQGP ? sQGP ? RHIC LHC ? 1.) is there a wQGP at the LHC ? 2.) is chiral symmetry decoupled from deconfinement in the sQGP ? 3.) are the degrees of freedom different in the sQGP and the wQGP ? 4.) does it matter if the partonic medium always de-excites through the quark soup phase ?

26 Chiral and deconfinement transitions still happen at the same temperature Interlude: news from Lattice QCD (Peter Petreczky, this conference) Critical Temp T c = MeV (around 40 MeV higher than T chem ) At high T deviation from ideal gas limit is only about 10%

27 SU(3) gauge theory (2+1) flavor QCD Resummed perturbative calculations from : Blaizot, Iancu, Rebhan, hep-ph/ Lattice data on pressure and entropy density at high temperatures can be described by re-summed perturbation theory Is 10% a large effect ? Comparison with re-summed perturbation theory, effective 3d theory and additional lattice data on quark number susceptibility and the Debye mass suggest that we have wQGP for T > 2 T c

28 AdS/CFT vs. lattice vs. HTL J. P. Blaizot, E. Iancu, U. Kraemmer, A. Rebhan, hep-ph/ AdS/CFT

29 Proton-proton collisions: unprecedented physics reach at LHC (charged particle spectra) (from the ALICE physics performance report (J.Phys.G32 (2006)1295)) enormous reach in multiplicity and transverse momentum.

30 HBT result: m T dependence of radius the same in pp and AA collisions. (Z. Chajecki, nucl-th/ ) Establish level of collectivity in high multiplicity pp events elliptic flow component ? (STAR coll., PRC 72 (2005) ) elliptic flow component ? (STAR coll., PRC 72 (2005) ) radial flow component ? (blastwave fits) (STAR coll., PRL 92 (2004) ) Program: measure identified spectra, flow & correlations as a function of multiplicity Hard component increases with N ch ? (STAR coll., PRD 74 (2006) ) n = 1 n = 2 n = 3 n = 11-12

31 Charged particle spectra in quark vs. gluon jets (CDF coll., PRL 94 (2005) ) Establish non-Abelian nature of fragmentation process in pp Identified particle spectra: breakdown of mt-scaling due to quark vs gluon jet production (STAR coll., nucl-ex/ ) Excitation function of baryon/meson ratios: fragmentation or recombination ? Program: measure identified spectra as a function of jet axis, jet energy, jet flavor

32 HI Experiments at the LHC ? All of them are interesting, clearly ALICE is the most versatile and superior HI detector, clearly CMS/ATLAS are superior in calorimeter based jet measurements.

33 Heavy Ion collisions: unprecedented physics reach at LHC from the ALICE EmCal proposal ALICE physics performance report (J.Phys.G32 (2006)1295)

34 What to expect at the higher energies ? Is there a significant change in coupling ? Is there a significant change in coupling ? Weaker coupling = larger mean free path = less flow = less v2 ? Weaker coupling = more viscosity = more entropy = much larger particle yields ? Detectors go black (‘Pisarski doomsday’ scenario) The first heavy ion day at the LHC will be very interesting

35 spatial eccentricity momentum anisotropy Elliptic flow: early creation P. Kolb, J. Sollfrank and U.Heinz, PRC 62 (2000) LHC: more viscosity, less flow ? (RB for R2D group, QM05) from RHIC to LHC: lifetime of QGP phase nearly doubles Most hydro calculations suggest that flow anisotropies are generated at the earliest stages of the expansion, on a timescale of ~ 5 fm/c if a QGP EoS is assumed.

36 Hydro pushes to higher pT at the LHC Ruuskanen et al., hep-ph/

37 Recombination pushes to higher pT at the LHC Thermal recombination pushes to higher pT because of higher parton. (Fries, Mueller, EJP C34(2004)S279) Shower recombination (from overlapping or neighboring jets) pushes recombination out to 20 GeV/c (Hwa, nucl-th/ )

38 Jet quenching will populate the recombination region at the LHC Borghini and Wiedemann (hep-ph/ ): solid lines: modified leading logarithm approximation (MLLA) dashed lines: introduce medium effects in parton splitting  =ln( E Jet / p hadron ) p T hadron ~2 GeV for E jet =100 GeV Fragmentation strongly modified at p T hadron ~1-5 GeV even for the highest energy jets

39 It will be challenging to interpret the intermediate pT region at the LHC pTpT pQCD Hydro ~ 2 GeV/c~ 6 GeV/c Soft Medium modified fragmentation (jet quenching) 0 p T independence of pbar/p ratio. p/  and  /K ratio increases with p T to > 1 at p T ~ 3-4 GeV/c in central collisions. Suppression factors of p,  different to that of , K 0 s in the intermediate p T region. Parton recombination and coalescence LHC, RHIC-II SPS, RHIC-I Thermal

40 Identified particle ratios inside and outside a jet (recombination predicts p/  = 5-20 out to 20 GeV/c) Determine the hadronization process & degrees of freedom in medium Identified particle correlations inside and outside a jet: Ridge vs. mach cone vs. fragmentation Program: study identified particle spectra, ratios and correlations as a function of jet energy, jet flavor, fractional momentum, medium path-length STAR coll., nucl-ex/ STAR coll., nucl-ex/ PHENIX coll., PRL 97 (2006)

41 Resonance formation inside and outside a jet & inside and outside a partonic medium Search for evidence of chiral symmetry restoration (C. Markert, this conference) Formation time argument: a.) General pQCD: Formation time [fm/c] ~ pT [GeV] b.) Specific string fragmentation (PYTHIA) formalism (Gallmeister, Falter, PLB630, 40 (2005)): High pT resonances form early c.) Vitev et al. (hep-ph/ ): heavy quarks fragment early, i.e. heavy resonances form early. side 1 side 2 near away Program: study resonance formation as a function of jet energy, jet flavor, jet axis, fractional momentum, medium path-length Low ptHigh pt Near sideNo medium or late hadronic medium No medium Away sideLate hadronic mediumPartonic or early hadronic medium (depends on formation time) CSR ? Side 1&2Late hadonic mediumEarly hadronic medium

42 The fate of strangeness enhancement at the LHC Canonical suppression in pp should reduce as a function of the incident energy The absolute yield rises but only linear with the yield of pions in a QGP The integrated yield is predictable, the pt-differential yield holds the new physics Hypothesis: due to the higher energy, the remaining differences between u,d and s quarks should significantly reduce (no Nbin scaling, same d.o.f.)

43 I.Kuznetsova & J.Rafelski, (this conference) oversaturated strange phase binds the charm quark ??  c  c

44 LHC R c AA (p T )/R b AA (p T ) Prediction –Taking the ratio cancels most normalization differences seen previously –pQCD ratio asymptotically approaches 1, and more slowly so for increased quenching (until quenching saturates) –AdS/CFT ratio is flat and many times smaller than pQCD at only moderate p T W. Horowitz, this conference

45  uons from W as a medium-blind reference (A.Dainese, this conference) pQCD predicts b/W crossing at p t muon ~ 30 GeV/c  from W should be unaffected by the medium b-quark energy loss would shift crossing to lower p t R AA

46 LHC Experiments: Muon Acceptance ALICE muon spectrometer: -4 1 GeV/c CMS, ATLAS: |  | 3.5 GeV/c High p t reach in Pb-Pb: about GeV/c

47 RHIC-II and LHC : unique places to study the complete onium program –Melting of quarkonium states (Deconfinement T C ) T diss (  ’) < T diss (  (3S)) < T diss (J/  )  T diss (  (2S)) < T diss (  (1S)) In order to resolve the question of melting of the states and its relevance to the QGP we need to measure: the J/  production mechanism (octet vs. singlet model) (requires pp) the effect of nuclear absorption (requires pA) the effect of thermal recombination the effect of co-mover absorption the feed-down from  c (in pp, pA,AA) all states (in pp, pA, AA) needs to be revised based on A. Mocsy talk

48 J/  : partonic recombination (PBM) Transport models show similar results based on hadronic recombination (Linnyk & Bravina, this conference)

49 Requirement: full coverage and excellent resolution in tracking and calorimetry  and pT broadening for  +jet  distribution for  c decay Y States resolution R2D

50 Summary – Questions for the LHC We have RHIC evidence for constituent quark scaling above T c. Is recombination the dominating hadronization process at RHIC and LHC energies ? Do the hadronizing degrees of freedom in the Quark Gluon Liquid have a dynamic mass ? Could there be a decoupling of the deconfinement transition and chiral symmetry restoration ? Is there another transition from the sQGP to the wQGP at LHC energies ? The excitation function (energy dependence) of v2 and R(AA) of identified particles will resolve many of the present ambiguities

51 Compelling reasons for RHI Physics (RHIC-II, FAIR, LHC) B.Jacak (QM06) Entirely new questions posed by RHIC  fast thermalization mechanism? *  how low is the viscosity of the liquid?  response of the plasma to deposited energy? *  what is the color screening length?  is the initial state a color glass condensate? * Early questions still outstanding  nature of phase transition? critical point?  equation of state of hot QCD matter?  do heavy quark bound states melt?  can dilepton observables provide evidence for chiral symmetry restoration? * could motivate new experiment

52 Ernest O. Lawrence (Nobel Prize, 1939) Father of ‘Big Science’ Let’s all work together because there is enough science for everyone !

53 Backup slides

54 What is missing in HI physics ? Detectors drive the physics output –Hadronic calorimetry –Track by track PID (not dE/dx driven) out to 20 GeV/c –Full tracking, PID and calorimetry out to forward rapidity Measurements –Identified hadron and resonance spectra out to very high pT  -jet,  c, Y(1s,2s,3s) measurements –Forward (low x) physics – CGC, fragmentation tests

55 A high energy detector for heavy ion physics R=2.8m Is it necessary, is it financially achievable ? LHC program will tell us

56 STAR preliminary Do the pT dependencies in the recombination results hint at a more ‘massive’ strange quark ? Light & strange baryon to meson ratios

57 Heavy quark energy loss dependencies (  s, gluon density) (S.Wicks, last call for LHC predictions)

58 Towards a quantitative result M. Stephanov hep-lat/ Large sensitivity to model inputs (such as quark masses), lattice sizes, and other assumptions