Summary of Experimental results: Photons, Leptons and Heavy Quarks at QM2008

Summary of Experimental results: Photons, Leptons and Heavy Quarks at QM2008Richard SetoFeb 9, 2008QM2008, Jaipur, India

Three topicsdi-leptons/photonsNA60RHIC heavy quarksRHIConiumRHIC

Concentrate on new information (subset)Will be RHIC-centric sincere apologies to folks with the very nice results from the SPS (other than NA60), lower energy experiments (HADES, KEK, JLAB,)and of course the RHIC folks whose results I do not mention

Otherwise I would have to talk for 1 hr (just kidding you dont want to listen to me for that long)

I have freely taken slides THANKS!

Where are we? (RHIC)Evidencesuppression of high pt mesonshigh energy densityflow early thermalization -> thermal radiation?charm quark- flow/suppressionStrongly interacting/low viscosity/entropywhat about B?Constituent quark scalingquasi-particle DOFan exercise after QM can you fit Ds and Bs into KE/nq scaling?What about deconfinement? the story of the J/psiWhat about chiral symmetry restoration low mass di-electronsExperimentallyCombinations eg. flow of charm or j/psi (a big step forward for experiments)correlations between various experimental observables e.g. direct or c/b: R_AA, v2, correlation functions

RHIC a cartoonhard processespre-equilibrium (CGC?)Cross over distinction between hadrons and quarks is ambiguous q* But correlations increase - DOF hard to think aboutpartonic thermalizationpartons cooling elliptic flow developshadrons more distincthadrons cool/decouple radial flow developsqq eeq*q * ee or** eeeeee means ee (PHENIX/STAR) or (Na60/PHENIX)Tc ~ 190 MeVTtimeTi=?sQGP9fm (?imaging)Paradigm switch that is hard for my brain

Di-leptons/virtual photons

NA 60 Low mass di-muon spectrumno mass shift of models of in medium spectral function modification (i.e. broadening) describe data below 900 MeV- beginning of restoration of chiral symmetry?

S. Damjanovic, Quark Matter 2008*Predictions by Rapp (2003) for all scenariosPhys. Rev. Lett. 96 (2006) 162302

S. Damjanovic, Quark Matter 2008*remember the NuXu plot? mass ordering of slopesNA 60 Low mass di-muon spectrumPhys. Rev. Lett. 96 (2006) 162302Radial flow develops in hadronic stage.

S. Damjanovic, Quark Matter 2008*NA60 a look at the slopesPhys. Rev. Lett. 96 (2006) 162302drop-Teff rises in low mass region radial flow of a hadronic source- drop at M~1 GeV suggests partonic nature of equilibrated particles~thermal radiation? - note: yield goes like (dN ch /dy)2

pp and AuAu normalized to p0 region

p+p: follows the cocktailAu+Au: large Enhancement in 0.15-0.75

p+p NORMALIZED TO mee

Experimental Knobs for in-medium modifications in a fireballSignal should increase with centralityLook for enhancement at low pt in central events

Me+esignalSignal should increase at low ptMe+eMe+eMe+e

Centrality Dependency

PT dependence of Au+Au MeeLow Mass excess is a low pT enhancement strongest in central events Behaves like a modified hadron

for 600-800 MeVSeveral theoretical schemes are OK, including dropping massFor 200-600 MeV none of the scenarios workIs there a partonic thermal component? Try hadronic scenarios?

Virtual photonsBackgrounds dalitz decaystrick : dalitz decays suppressed by factor

Use mee>M where M=MCompare to cocktail

Fraction of direct photonsFraction of direct photonsCompared to direct photons from pQCDp+pConsistent with NLO pQCDAu+AuClear excess above pQCD = 0.5pT = 1.0pT = 2.0pTp+pAu+Au (MB)Now multiply by Inclusive yield

The spectrumCompare spectra to NLO pQCDp+p consistent with pQCDAu+Auabove binary scaled pQCDIf excess of thermal origin: inverse slope is related to initial temperature

To do fit for T!?

heavy quarks throw a pebble in the stream

see if it moves

bouldermu~3 MeVmd~5 MeVms~100 MeVmc~1,300 MeVmb~4,700 MeV

QCD~200 MeVPooh and Rabbit playing pooh sticks

Centrality Dependence of RAA Non photonic electrons (aka charm+bottom)PRL 98, 172301 (2007)high pT non-photonic e suppression increases with centrality similar to light hadron suppression at high pTcareful: decay kinematics!updated result on flow of non-photonic e saturation at pT ~ 2.5 GeVcharm suppressed and thermalizesWhat fraction of this is bottom?

STAR (PHENIX also uses this technique)Answer: measure B/B+C

STARNear- and away-side correlation peak expected for B productionSTAR and PHENIX both have ways of separating charm and bottom

Bottom fraction

A blemish.Charm cross-sectionBoth STAR and PHENIX are self-consistent.STAR results ~ 2 times larger than PHENIXSome work to do for PHENX and STAR (another try)

Estimating h/stransport modelsRapp & van Hees (PRC 71, 034907 (2005))diffusion coefficient required for simultaneous fit of RAA and v2 DHQx2pT ~ 4-6at mB = 0 e + P = Tsthen h/s = (1.3-2.0)/4pMoore & Teaney (PRC 71, 064904 (2005))calculate perturbatively (and argue that plausible also non-perturbatively)DHQ/ (h/(e+P)) ~ 6 (for Nf = 3)consistent with other calculations of /s

Conclusion- heavy quarksB suppressed, and flowsthis must mean thermalization of the B quark (or at least many of them)

Mechanism? clearly QCD but in the non perturbative regimeremember sQGP~non pertubative or hadronic methodsVitev et al B Meson suppression (like J/psi)Rapp/Hess resonant interactions of heavy quarks in sQGP with D/B mesons (remember hadrons/quark ambiguous)AdSCFT Teany, Castleberry Solana, AMY, Gubser etc

The J/psiAn interesting* story

* depending on your mood you can takethis to mean exciting, intriguing, confusing

Good news from the lattice screening a good picture

I hope this holds upRBC-Bielefeld Collab. (2007) Free energy of a static ccFor the First Time Agreement between potential model and lattice correlators to few % and for all statesStrong screening seen in Lattice We can use onium states as thermometer (OK - the lattice is static and we have to use a dynamical model)

BUT

Whats newCuCu and new Run-7 data confirms previous [email protected], there is more suppression at forward rapidity where the energy density is lowertwo ideasfinal state: recombinationinitial state:saturation (aka CGC)shadowingdAu should give us a handle on initial state effects

Cold matter. Using the dAu (reanalyzed data)

In a Glauber data-driven model, propagate what we know from RdA(y,centrality) to build up the a model for AuAu No shadowing scheme nor absorption schemePHENIX, arxiv:0711.3917Forward rapidity MidrapidityAt the moment, the PHENIXdAu data is not good enough to saywhether or not cold nuclear mattereffects can totally explain the mid-rapiditydata.

RHIC run 8 dAu 30 x run 3 !Lets wait for this run analysis before to say more about cold matter Rafael GdC*/29

RAA at high pTSTAR0-60%AuAuCuCuPHENIX prelimSTAR prelimDoes the RAA return to 1 at high pT?But there is energy loss of charm?

Could the cc be in a singlet state (then it would be colorless and pass freely through the sQGP)Or maybe we are jumping to conclusions wait for more accurate measurementsshh..I am thinking about the hot wind0-60%

let me now draw a couple conclusions which (I think) will hold up B (bottom, beauty..) flows and is suppressedB/(B+C) measuredv2 strength and R_AA suppression of c/b -> electrons in AADileptons and photons enhanced

(I ignore the J/ now since it still needs much more clarification i.e. data and data analysis)

Good progress for 1 year BUT

Can we begin to make these statements stronger?What would it take for us to say charm and bottom are thermalized early thermal radiation tell us the initial temperature is XX

So what?There are clearly many questions to be answeredWhat are sources of the excess di-leptons/photons? are they telling us a temperature? if so what is it?How do the heavy quarks manage to become part of the bulk? how strong is the s in sQGP? what is the viscosity (can we trust our calculation?)Does the J/ show anomalous suppression? More at high y?It is an exciting time we now have powerful tools to begin to answer these thingse.g. flow of J/, correlations measurements (e.g. charm+jet.), excess dileptons/photons

*******80 nb 1 *