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Dileptons from Strongly Coupled quark-gluon plasma (sQGP)

Dileptons from Strongly Coupled quark-gluon plasma (sQGP). Edward Shuryak Department of Physics and Astronomy State University of New York Stony Brook NY 11794 USA. Background:. New spectroscopy of sQGP

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Dileptons from Strongly Coupled quark-gluon plasma (sQGP)

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  1. Dileptons from Strongly Coupled quark-gluon plasma (sQGP) Edward Shuryak Department of Physics and Astronomy State University of New York Stony Brook NY 11794 USA Trento 05 Shuryak

  2. Background: • New spectroscopy of sQGP • Multiple bound states, 90% of them colored. If so, it explains several puzzles related to lattice results: • Why resonances in correlators (J/ from MEM)? • How rather heavy quasiparticles can create high pressure already at T= 1.5-2 Tc? Motivations: • Reduced scale => enhanced coupling • Hydro works and QGP seem to have remarkably small viscosity • Lattice bound states and large potentials Trento 05 Shuryak

  3. Outline – main ideas Jet quenching due to ``ionization” of new bound states (I.Zahed+ES) Vectors in QGP and dileptons: Bound states (,,) in L and T forms, and a near-threshold bumpcan tell us what are thequasiparticle masses and interaction strength in QGP (Jorge Casalderrey +ES) Trento 05 Shuryak

  4. Can we verify existence of bound states at T>Tc experimentally?Dileptons from sQGP: an idea M=1.5-2 GeV M=.5-.8 GeV Trento 05 Shuryak

  5. Motivation 1: RHIC produces ``matter”, not a fireworks of partons, => hydro and thermodynamics work • Good equilibration (including strangeness) is seen in particle rations (as at SPS) • the zeroth order in l/L , an ideal hydro, works well (except in hadroic phase) • Viscosityis the O(l/L) effect, » velocity gradients. Note thatl» 1/( n) and hydro is (the oldest) strong coupling expansion tool. /s =.1 -.2 l << L (the micro scale) << (the macro scale) (the mean free path) << (system size) (relaxation time) << (evolution duration) I Trento 05 Shuryak

  6. ES,Nucl.Phys.A717:291,2003 How strong is strong interaction and where?How large can s be in QGP ? • In a QCD vacuum the domain of perturbative QCD (pQCD) is limited by non-pert. phenomena, e.g. by the Q> 1 GeV as well as by confinement: so s< 0.3 • At high T we get weak coupling because of screening <(gT) << 1 (the Debye mass Md sets the scale) • In between, Tc<T<few Tc, there is no chiral/conf. scales While Md=2T= 350-400 MeV is not yet large: can s(Md) be .5-1 (?). If so, binding appears. (ES-Zahed,03) Trento 05 Shuryak

  7. New QCD Phase Diagram, which includes ``zero binding lines”(ES+I.Zahed hep-ph/030726) T The lines marked RHIC and SPS show the adiabatic cooling paths Chemical potential B Trento 05 Shuryak

  8. lattice puzzles • Since Matsui-Satz and subsequent papers it looked like even J/,c dissolves in QGP (thus it was a QGP signal) • And yet recent works (Asakawa-Hatsuda,Karsch et al) have found, using correlators and MEM, that they survive up to about T=2Tc . What was wrong? Trento 05 Shuryak

  9. New ``free energies” for static quarks (from Bielfeld) • Upper figure is normalized at small distances: one can see that there is large ``effective mass” for a static quark at T=Tc. • Both are not yet the potentials! • The lower figure shows the effective coupling constant Trento 05 Shuryak

  10. Fitting F to screened Coulomb • From Bielefld hep-lat/0406036 • Note that the Debye radius • produces ``normal” coupling, • but the coeff. is larger • It becomes still larger if V is used • instead of F, see later Trento 05 Shuryak

  11. For a screened Coulomb potential, a simple condition for a bound state • (4/3)s (M/MDebye) > 1.68 • M(charm) is large, Md is only about 2T • If (Md) indeed runs and is about ½-1, it is large enough to bind charmonium till about T=3Tcor about 500 MeV (which is above the highest T at RHIC) • Since q and g quasiparticles are heavy, M appr. 3T, they all got bound as well ! Trento 05 Shuryak

  12. Digression:Relativistic eqns have a critical Coulomb coupling for falling onto the center (known since 1920’s) • (4/3)s=1/2 is a critical value for Klein-Gordon eqn, at which falling onto the center appears. (It is 1 for Dirac). Trento 05 Shuryak

  13. New potentials (cont):after the entropy term is subtracted,potentials become much deeper this is how potential I got look like for T = 1; 1.2; 1.4; 2; 4; 6; 10Tc, from right to left, from ES,Zahed hep-ph/0403127 Trento 05 Shuryak

  14. Here is the binding and |psi(0)|^2 Trento 05 Shuryak

  15. If a Coulomb coupling is too strong,falling onto the center may occur:but it is still rather difficult to get a bindingcomparable to the massBut we need massless pion/sigma at T=>Tc ! • Brown,Lee,Rho,ES hep-ph/0312175 : near-local interaction induced by the ``instanton molecules” (also called ``hard glue” or ``epoxy”, as they survive at T>Tc • Their contribution is » |(0)|2 which is calculated from strong Coulomb problem Trento 05 Shuryak

  16. Solving for the bound statesES+I.Zahed, hep-ph/0403127 • In QGP there is no confinement => Hundreds of colored channels may have bound states as well! Trento 05 Shuryak

  17. The pressure puzzle (GENERAL) • Well known lattice prediction (numerical calculation, lattice QCD, Karsch et al) the pressure as a function of T (normalized to that for free quarks and gluons) • This turned out to be the most misleading picture we had, fooling us for nearly 20 years • p/p(SB)=.8 from about .3 GeV to very large value. Interpreted as an argument that interaction is relatively weak (0.2) and can be resumed, although pQCD series are bad… • BUT: we recently learned that storng coupling leads to about 0.8 as well! Trento 05 Shuryak

  18. (The pressure puzzle, cont.) • How quasiparticles, which according to direct lattice measurements are heavy (Mq,Mg = 3T) (Karsch et al) can provide enough pressure? (exp(-3) is about 1/20) • (The same problems appears in N=4 SUSY YM, where it is parametric, exp(-1/2) for large =g2Nc>>1) Trento 05 Shuryak

  19. The pressure puzzle is resolved! Trento 05 Shuryak

  20. Other observables at T>Tc? • Viscosity, charm diffusion coefficient => are binary resonances enough? Chains \bar q g … g q? • Succeptibilities at nonzero mu have large peaks (Karsch et al, mu/T^6 paper): => is N bound at T>Tc? Or only diquarks? • V.Koch et al: what about <SB>/<S^2>? => (strange B)/(strange B+M) or (qs vs \bar q s bound states)(T) Trento 05 Shuryak

  21. Can we verify existence of bound states at T>Tc experimentally?Dileptons from sQGP: Trento 05 Shuryak

  22. Quark mass and the interactionstrength (“s”) via dileptons • Example: pp(gg) -> t t at Fermilab has a bump near threshold (2mt) due to gluon exchanges. • The Gamow parameter for small velocity z= (4/3)s/v; can be > 1, • Produces a bump (or jump): the • Factor z/(1-exp(-z)) • Cancels v in phase space • Three objects can be seen at nonzero p, T,L bound states (at fixed T<Tz.b.about 2 Tc) and the near-threshold enhancement (``bump”), at any T • Why bump? Because attraction between anti-q q in QGP enhances annihilation Trento 05 Shuryak

  23. a nonrelativistic approach with realistic potentials (Jorge Casalderrey +ES,2004) Trento 05 Shuryak

  24. Following the methods developed for t quark • Khose and Fadin: sum over states, then Strassler and Peskin: Green function can be formed of 2 solutions • We get 2 solutions numerically and checked that published t-pair production for Coulomb is reproduced up to .2 percent! • Then we used it for ``realistic” potentials Trento 05 Shuryak

  25. Study of near-endpoint annihilation rateusing non-rel. Green function, for lattice-based potential (+ instantons) Im(M) for T=1… 2 Tc(a warning: very small width) Trento 05 Shuryak

  26. Total width is 20,100 or 200 MeV Trento 05 Shuryak

  27. Width is not to be trusted ! Asakawa-Hatsuda, T=1.4Tc Karsch-Laerman, T=1.5 and 3 Tc Trento 05 Shuryak

  28. Scattering amplitudesfor quasiparticlesM. Mannarelli. and R. Rapp hep-ph/05050080\bar q q scattering no q - gluon scattering yet Trento 05 Shuryak

  29. QUARK-HADRON DUALITY AND BUMPS IN QCD: A simple exercise with all M scaling as T (the worse case scenario) Operator product expansion tells us that the integral Under the spectral density should be conserved (Shifman, Vainshtein, Zakharov 78). Three examples which satisfy it (left) the same after realistic time integral Over the expanding fireball (as used in Rapp+ES paper on NA50), divided by a ``standard candle” (massless quarks) (right) Trento 05 Shuryak

  30. Summary on dileptons • In general, 3*3 objects (for each rho, omega and phi states):L,T vectors plus a near-threshold bump • Most observable is probably T=Tc when Vs are about .5-.8 GeV in mass • Possibly observable enhancement is in the region 1.5-2 GeV, where 2Mq is about constant in a wide T interval. Not to be present at SPS but at RHIC • Realistic potential predicts quite interesting shapes, but the width(and resolution) issue is so far not quite quantitive. • Sound waves became narrow in strong coupling: can this mix with omega and produce dileptons? Trento 05 Shuryak

  31. Jet quenching by ``ionization”of new bound states in QGP? Trento 05 Shuryak

  32. Calculation of the ionization rateES+Zahed, hep-ph/0406100 • Smaller than radiative loss if L>.5-1 fm • Is there mostly near the zero binding lines, • Thus it is different from both radiative and elastic looses, which are simply proportional to density • Relates to non-trivial energy dependence of jet quenching (smaller at 62 and near absent at SPS) dE/dx in GeV/fm vs T/Tc for a gluon 15,10,5 GeV. Red-elastic, black -ionization Trento 05 Shuryak

  33. Lattice EoS is about confirmed, QGP seems to be the most ideal fluid known /s = .1-.2 => QGP at RHIC is in a strong coupling regime => New spectroscopy: many old mesons plus hundreds of exotic colored binary states Dileptons is a way to measure masses of qs and the strength of their interactions, via resonances and near-threshold bumps Conclusions: Trento 05 Shuryak

  34. Additional slides

  35. Sonic boom from quenched jets Casalderrey,ES,Teaney, hep-ph/0410067; H.Stocker… • the energy deposited by jets into liquid-like strongly coupled QGP must go into conical shock waves, similar to the well known sonic boom from supersonic planes. • We solved relativistic hydrodynamics and got the flow picture • If there are start and end points, there are two spheres and a cone tangent to both

  36. Distribution of radial velocity v_r (left) and modulus v (right).(note tsunami-like features, a positive and negative parts of the wave)

  37. Is such a sonic boom already observed?Mean Cs=.33 time average over 3 stages=> =+/-1.23=1.91,4.37 flow of matter normal to the Mach cone seems to be observed! See data from STAR, M.Miller, QM04

  38. PHENIX jet pair distribution Note: it is only projection of a cone on phi Note 2: more recent data from STAR find also a minimum in <p_t(\phi)> at 180 degr., with a value Consistent with background

  39. Away <pT> vs centrality STAR,Preliminary Away core <pT> drops with centrality faster than corona <pT>. Core hadrons almost identical to medium in central collisions. A punch-thorugh at the highest trigger?

  40. Preliminary away <pT> dependence on angle (STAR,preliminary) <pT> (phi) has a dip structure in central AA. Mach shock wave?

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