dileptons from strongly coupled quark-gluon plasma (sqgp)

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Dileptons from Dileptons from Strongly Strongly CoupledCoupled quark-gluon plasma quark-gluon plasma

(sQGP)(sQGP)

Edward ShuryakEdward ShuryakDepartment of Physics and AstronomyDepartment of Physics and Astronomy

State University of New YorkState University of New York

Stony Brook NY 11794 USAStony Brook NY 11794 USA


Background: Background:

Motivations:Motivations: Reduced scale Reduced scale

=> enhanced => enhanced couplingcoupling

Hydro works Hydro works and QGP seem and QGP seem to have to have remarkably remarkably small viscosity small viscosity

Lattice bound Lattice bound states and states and large potentialslarge potentials

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?


Outline – main ideasOutline – main ideas

Vectors in QGP and Vectors in QGP and dileptons:dileptons:

Bound states (Bound states (,,,,) ) in L and T forms, in L and T forms, and a and a near-threshold near-threshold bumpbump can tell us can tell us what are thewhat are the quasiparticle quasiparticle masses and masses and interaction strength interaction strength in QGPin QGP

(Jorge Casalderrey (Jorge Casalderrey +ES)+ES)

Jet quenching due to ``ionization” of new bound states

(I.Zahed+ES)

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Can we verify existence of bound states at T>Tc experimentally?Dileptons from sQGP: an idea

M=.5-.8 GeV

M=1.5-2 GeV


Motivation 1: RHIC produces ``matter”, Motivation 1: RHIC produces ``matter”, not a fireworks of partonsnot a fireworks of partons, => , => hydro and thermodynamics workhydro and thermodynamics work

l << Ll << L(the micro scale) << (the macro scale)(the micro scale) << (the macro scale)(the mean free path) << (system size)(the mean free path) << (system size)(relaxation time) << (evolution duration) (relaxation time) << (evolution duration)

II •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)

•Viscosity is the O(l/L) effect, » velocity gradients. Note

that l» 1/( n) and hydro is (the oldest) strong coupling expansion tool. /s =.1 -.2

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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)

ES,Nucl.Phys.A717:291,2003

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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

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lattice puzzleslattice puzzles

Since Matsui-Satz and subsequent papers Since Matsui-Satz and subsequent papers it looked like even it looked like even J/J/,,cc dissolves in QGP dissolves in QGP

(thus it was a QGP signal)(thus it was a QGP signal)

And yet recent works (Asakawa-And yet recent works (Asakawa-Hatsuda,Karsch et al) have found, using Hatsuda,Karsch et al) have found, using correlators and MEM, that correlators and MEM, that they survive up they survive up to about T=2Tc .to about T=2Tc . What was wrong? What was wrong?


New ``free energies” for static New ``free energies” for static quarks (from Bielfeld)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

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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 usedinstead of F, see later


For a screened Coulomb potential, a simple condition for a bound state (4/3)s (M/M

Debye) > 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 !


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).


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


Here is the binding and |psi(0)|^2


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


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!


The pressure puzzle The pressure puzzle (GENERAL)(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!


(The pressure puzzle, cont.)(The pressure puzzle, cont.)

How quasiparticles, which according to How quasiparticles, which according to direct lattice measurements are direct lattice measurements are heavy heavy (Mq,Mg = 3T)(Mq,Mg = 3T) (Karsch et al) can provide (Karsch et al) can provide enough pressure?enough pressure? (exp(-3) is (exp(-3) is about about 1/20)1/20)

(The same problems appears in N=4 (The same problems appears in N=4 SUSY YM, where it is parametric, SUSY YM, where it is parametric, exp(-exp(-1/21/2) for large ) for large ==gg22NNcc>>>>1)1)


The pressure puzzle is resolved!


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)


Can we verify existence of bound states at T>Tc experimentally?Dileptons from sQGP:


Quark mass and the interaction strength (“s”) via dileptons

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

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): theFactor z/(1-exp(-z))Cancels v in phase space


a nonrelativistic approach with realistic potentials (Jorge Casalderrey +ES,2004)


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


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)


Total width is 20,100 or 200 MeV


Width is not to be trusted !

Asakawa-Hatsuda, T=1.4Tc

Karsch-Laerman, T=1.5 and 3 Tc


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


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 integralOver the expanding fireball (as used in Rapp+ES paper on NA50), dividedby a ``standard candle” (massless quarks) (right)


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?


Jet quenching by ``ionization”of new bound states in QGP?


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


Conclusions: Conclusions:

Lattice EoS is about Lattice EoS is about confirmed, confirmed,

QGP seems to be the QGP seems to be the most ideal fluid most ideal fluid known known

/s = .1-.2 /s = .1-.2 => QGP at RHIC is in => QGP at RHIC is in

a strong coupling a strong coupling regime => regime => New New spectroscopy:spectroscopy: many many old mesons plus old mesons plus hundreds of exotic hundreds of exotic colored binary statescolored binary states

Dileptons is a Dileptons is a way to measure way to measure masses of qs masses of qs and the strength and the strength of their of their interactions, via interactions, via resonances and resonances and near-threshold near-threshold bumpsbumps

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Additional slidesAdditional slides

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Sonic boom from quenched Sonic boom from quenched jets jets Casalderrey,ES,Teaney, hep-ph/0410067; Casalderrey,ES,Teaney, hep-ph/0410067;

H.Stocker…H.Stocker…

• the energy deposited the energy deposited by jets into liquid-like by jets into liquid-like strongly coupled QGP strongly coupled QGP must go into must go into conical conical shock wavesshock waves, similar , similar to the well known to the well known sonic boom from sonic boom from supersonic planes.supersonic planes.

• We solved relativistic We solved relativistic hydrodynamics and hydrodynamics and got the flow picture got the flow picture

• If there are start and If there are start and end points, there are end points, there are two spheres and a two spheres and a cone tangent to bothcone tangent to both

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

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Is such a sonic boom already Is such a sonic boom already observed?observed?Mean Cs=.33 time average over 3 stages=>Mean Cs=.33 time average over 3 stages=>

M.Miller, QM04

flow of matter normal to the Mach cone seems to be observed! See data from STAR,

+/-1.23=1.91,4.37

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PHENIX jet pair distribution 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

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Away <pAway <pTT> vs > vs centralitycentrality

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?

STAR,Preliminary

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away <pT> dependence on away <pT> dependence on angle angle (STAR,preliminary)(STAR,preliminary)

Preliminary

<pT> (phi) has a dip structure in central AA.

Mach shock wave?

dileptons from strongly coupled quark-gluon plasma (sqgp)

Documents

shuryak background

shuryak digression

shuryak motivation

high t

shuryak new potentials

highest t

t forms

shuryak fitting f