Zhangbu Xu (Brookhaven National Lab)

Free Quarks Constituent Quark Scaling of FlowHeavy Quark ThermalizationColor Screening of Heavy Quarkonia

Excited Vacuum Novel symmetries in QCDDileptons as tool to systematically study Chiral Symmetry

Restoration

(Super-)Statistical Fluctuation in particle productionInitial state of gluonic matter in nuclear collisionsSearch for Critical Point

Recent RHIC Heavy-Ion Results

2

STAR Preliminary

3

Quark Matter 1995

1.FREE QUARKS2.EXCITED VACUUM

4

NCQ Scaling

STAR, arXiv:0909.0566 [nucl-ex] PHENIX, PRL 99, 052301 (2007)

d(p+n) : nq = 2 x 3 3He(2p+n) : nq = 3 x 3Number of constituent quark scaling holds well for v2 of 3He.

5

Beam Energy and Species

• Many measurements show impressive scaling• Many others show deviations:

• PID v2 by ALICE• U+U 0-2% PID v2 by PHENIX • Different pt ranges and centralities

S.S. Shi, QM2012

Sakaguchi, S.L. Huang, QM2012

6

Flow of Heavy Quarks

First measurement of directly reconstructedCharmed hadron radial flow at RHIC

Elliptic flow of Electrons from heavy-flavor hadronsDifferent flow methods: large flow at low ptJet contribution at high pt

Dong, Wei, Tlusty QM2012

7

Integrated J/ yield

Npart dependence of J/ RAA: less suppression at LHC compared to at RHIC in central collisionsinterplay between CNM, color screening and ccbar recombinationconsistent with more significant contribution from ccbar recombination at LHC energies

ALICE: Arnaldi, Arsene, Safarik, Scomparin PHENIX: PRC84(2001)054912

8

J/ pT dependence in A+A CMS: Mironov, Moon, Roland

ALICE: Arnaldi, Safarik, Scomparin, Yang

STAR: arXiv: 1208.2736, Trzeciak, Xie PHENIX: PRL98(2007)232301

J/ RAA decreases from low to high pT at LHC.J/ RAA increases from low to high pT at RHIC.

At high pT, J/ more suppressed at LHC. Models incorporating color screening andrecombination can consistently

describe the J/ suppression pattern and flow measurements.

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Suppression without flowRHIC: large suppression, zero flowLHC: less suppression, hints of flow

Color Screening and quark coalescence

STAR Preliminary

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Suppression in A+A

(1s) suppression magnitude consistent with excited states suppression. (2S) strongly suppressed, (3S) completely melted.

Last piece of convincing evidence: color screening features of hot, densemedium in light of RHIC and LHC precise quarkonium measurements.

STAR: Dong, Trzeciak, Xie (QM2012)CMS: arXiv: 1208.2826, Mironov, Rangel, Roland

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Novel SymmetriesLocal Parity Violation Chiral Symmetry

STAR, PRL 103, 251601

Crucial to verify if parity violation is the correct explanation

U+U collisions: collisions with more v2 and less B field than Au+Au

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Beam energy scan

From 2.76 TeV to 7.7 GeV, changes start to show from the peripheral collisions. (Wang, QM2012)

ALICE, arXiv:1207.0900

1313

• A dedicated trigger selected events with 0-1% spectator neutrons.

• With the magnetic field suppressed, the charge separation signal disappears (while v2 is still ~ 2.5%).

Chiral Magnetic in U+U

• The difference between OS and SS is still there in U+U, with similar magnitudes.

• Consider OS-SS to be the signal

0-5%

70-80%

20-40%STAR Preliminary

(Wang, QM2012)

14

Electric QuadrupoleY. Burnier, D. E. Kharzeev, J. Liao and H-U Yee,

Phys. Rev. Lett. 107, 052303 (2011)

Wang, QM2012 Chiral Magnetic Wave

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Energy dependence of di-electron spectra

PHENIX HBD results at 200 GeV : consistent with previous publication in 20-92% centrality.STAR results: systematically study the di-electron continuum from 19.6, 39, 62.4 and 200 GeV.Observe enhancement above cocktails in low mass range (~0.5 GeV/c2)

20-40%

PHENIX: Atomssa, TserruyaSTAR: Dong, Geurts, Huang, Huck

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pT (GeV/c)

Direct photon spectra and elliptic flow

Low pT direct photon elliptic flow measurement could provide direct constraints on QGP dynamics (η/s, T, t0…).

Excess of direct photon yield over p+p: Teff=221 ± 19 ± 19 MeV in 0-20% Au+Au; substantial positive v2 observed at pT<4 GeV/c. Di-lepton v2 versus pT & Mll: probe the properties of the medium from hadron-gas dominated

to QGP dominated. (R. Chatterjee, D. K. Srivastava, U. Heinz, C. Gale, PRC75(2007)054909)

PHENIX, arXiv: 1105.4126

PHENIX: PRL104 (2010)132301

Ruan, QM2012

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Di-electron v2 at 200 GeV Au+Au Cocktail simulation is consistent with the

measured di-electron v2 at Mee<1.1 GeV/c2.

Need a factor of two more data to be sensitive to hardon gas and QGP contribution, in addition to independent measurements to disentangle ccbar correlation contribution

R. Chatterjee, D. K. Srivastava, U. Heinz, C. Gale, PRC75(2007)054909)STAR: Cui, Geurts, Huang QM2012

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Quantify the EnhancementsTemperature dependence of rho spectral function

1. Beam energy range where final state is similar2. Initial state and temperature evolution different3. Density dependence by Azimuthal dependence (v2)4. Use centrality dependence as another knob

19

STAR: Cui, Dong, Geurts, Huang, Huck

A tool to study Chiral Symmetry Restoration

NA60, Eur.Phys.J.C59(2009)607

CERES: Eur.Phys.J.C41(2005)475

Ruan, QM2012

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Pillars of Discoveries in QGP physicsHorowitz,1104.4958

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Cold QCD matter – the initial state at RHIC

RHIC may provide unique access to the onset of saturation

2000—2008: yields 2008—: mono-jet 2009—: statistics/fluctuation

ppperipheral dAu central dAu

STAR preliminary

PHENIX, PRL107

22

Counting (Glittering)

PHENIX PRC 78

Tribedy, Venugopalan PLB710

Gelis, Lappi, McLerran, NPA 828 (2009)

23

Where is the QCD critical point?

A landmark on the QCD phase diagram

24

Thermodynamic properties of hot QCD stateA thermodynamic state is specified by a set of values of all

the thermodynamic parameters necessary for the description of the system. --- statistical mechanics by K. Huang

Temperature (T), chemical potential (m), pressure(P), viscosity () …

1. Chemical/thermal Equilibrium at certain stage of the evolution

2. At the predicted QCD phase boundary

3. persistent from SPS to RHIC

4. Temperature decreases at AGS and SIS

A. Andronic et al., NPA 837 (2010) 65

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Predictable Production Rate

Why is it so predictable?T=164MeV?

)//(/33 pHeH

HeHe 34 /

+ -A. Andronic, P. Braun-Munzinger, J. Stachel, and H. Stocker, Phys.Lett.B697:203-207,2011

26

Directed Flow of Protons• Directed flow (v1) slope:

sensitive to 1st order phase transition.

• Proton v1 slope changes sign from + to – between 7.7 and 11.5 GeV and

remains small but negative up to 200 GeV.

• v1 slopes for other particles are all negative.

• “net-proton” v1 slope shows a minimum around 11.5-19.6 GeV.

• AMPT/UrQMD models cannot explain data.

26

(GeV) Pandit, Dong (STAR), QM2012

27

Higher Moments of Net-protons

Net-proton/Net-charge/Net-kaon

X.F. Luo, L.Z. Chen for STAR, QM2012

28

Negative Binomials fit all data

Net charge

Net kaon

29

Negative-Binomial Distribution vs. Tsallis

nk

kn

)km(km

!n)1nk()1k(k)n(P

kn )1t(

km1t)n(P)t(F

k/mmDmn

22

generatingfunction:

average andvariance:

k = - Nbinomial

distributionN/mmD

mn22

N

)1t(Nm1)t(F

k = Poisson

distribution

)1t(mexp)t(F

mDn 2

Aguiar, Kodama, PA320, 2003

1q

p1S a

qa

Tsallis entropy:

Non extensivity:

)B(S)A(S)1q()B(S)A(S)BA(S

)1q/(1q ]x)1q(1[)x(exp

ma

qaaqq )NE(expZ

“Partition function”:

30

Spectra by same statistics

Are Heavy-Ion collisions governed by a set of generic statistic rules, which also exist in other complex systems?What does this physics tell us about statistics in complex systems. How do we use the existing tools to extract information beyond “normal” statistics?

31

Aims and scopeTo bring together scientists who have made contributions to Tsallis

entropy and those who study complex systems. In physics, the Tsallis entropy is a generalization of the standard

Boltzmann-Gibbs entropy. It was introduced in 1988 by Constantino Tsallis as a basis for generalizing the standard statistical mechanics. In the scientific literature, the physical relevance of the Tsallis entropy was occasionally debated. However, from the years 2000 on, an increasingly wide spectrum of natural, artificial and social complex systems have been identified which confirm the predictions and consequences that are derived from this nonadditive entropy, such as nonextensive statistical mechanics, which generalizes the Boltzmann-Gibbs theory.

Among the various experimental verifications and applications presently available in the literature, the following ones deserve a special mention:

- The distribution characterizing the motion of cold atoms in dissipative optical lattices, predicted in 2003 and observed in 2006.

- The fluctuations of the magnetic field in the solar wind enabled the calculation of the q-triplet (or Tsallis triplet) .

- Spin glass relaxation.- Trapped ion interacting with a classical buffer gas.- High energy collisional experiments at LHC/CERN (CMS,

ATLAS and ALICE detectors) and RHIC/Brookhaven (STAR and PHENIX detectors).

Among the various available theoretical results which clarify the physical conditions under which Tsallis entropy and associated statistics apply, the following ones can be selected:

- Anomalous diffusion.- Uniqueness theorem.- Sensitivity to initial conditions and entropy production at the

edge of chaos.- Probability sets which make the nonadditive Tsallis entropy to be

extensive in the thermodynamical sense.- Strongly quantum entangled systems and thermodynamics.- Thermostatistics of overdamped motion of interacting particles.- Nonlinear generalizations of the Schroedinger, Klein-Gordon and

Dirac equations.

32

Understanding Symmetry and DOF RHIC is the best facility to study

novel symmetries and critical point: flexible machine to change

conditions beam species (magnetic field), BES (turn on/off QGP)

Large Acceptance (good for both LPV and chiral symmetry)

Excellent lepton PID (both electrons and muons at midrapidity, who else has that!)

Since the beginning of physics, symmetry considerations have provided us with an extremely powerful and useful tool in our effort to understand nature. Gradually they have become the backbone of our theoretical formulation of physical laws. — Tsung-Dao LeeParticle Physics and an Introduction to Field

Theory (1981), 177

LPV: beam energy:

deconfinement, chiral symmetry Beam species:

magnetic field Medium effect on vector

mesons (chiral symmetry, resonant states):

beam energy; Spectra and v2 vs Ml+l-

HFT+MTD+VTX upgrade 2017- First glimpse of dilepton spectra

around 0 and 1<M<3GeV Heavy-flavor flow

Beyond 2017 Phase II BES sPHENIX Detailed studies of DOF黄鹤一去不复返还