study qcd phase diagram in high-energy nuclear collisions · nu xu “new frontiers in qcd ... dec....

Nu Xu 1/38 “New Frontiers in QCD”, Kyoto, Nov. 18 – Dec. 20, 2013

QCD Emergent Properties

Study QCD Phase Diagram in High-Energy Nuclear Collisions

Nu Xu

(1) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA

(2) College of Physical Science & Technology, Central China Normal University, China

Many Thanks to the Organizers!


Outline

1) Introduction: QCD Phase Structure

2) Part I: STAR BES-I Results (selected)

3) Part II: Quarkonia in HIC



1)  After the discover of the Higgs boson the QCD degrees of freedom are well defined, at short distance.

2)  Study dynamical structures of matter that made from q, g. E.g. the confinement, nucleon spin, the QCD phase structure... Large αS and strong coupling – QCD at long distance.

Short distance

Long distance

ELEMENTARY PARTICLES


Study QCD Phase Structure at RHIC Observables: 1st order phase transition

(1) Azimuthally HBT

(2) Directed flow v1

Partonic vs. hadronic dof

(3) RAA: N.M.F.

(4) Dynamical correlations

(5) v2 - NCQ scaling*

Critical point, correl. length

(6) Fluctuations* (7) Di-lepton production* Study QCD Phase Structure

- Phase boundary? - Critical point?


BES-I: √sNN = 7.7, 11.5, 19.6, 27, 39GeV


Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006

RHIC! BRAHMS"PHOBOS"PHENIX"

STAR"

AGS!

TANDEMS!

v = 0.99995⋅c = 186,000 miles/sec Au + Au at 200 GeV

Animation M. Lisa

- RHIC: The high-energy heavy-ion collider (i) Dedicated QCD collider (ii) √sNN = 200 - 5 GeV (iii) U, Au, Cu, d, p

- RHIC: The highest energy polarized proton collider! √s = 200, 500 GeV


Part I

Recent Results from RHIC BES-I Program


STAR Experiment TPC MTD Magnet BEMC BBC EEMC TOF

HFT


Particle Identification at STAR

TPC

TOF

EMC

HFT

Neutral particles

e, µ

π K p d

TPC TOF TPC

Log10(p)

Multiple-fold correlations for the identified particles!

Hyperons & Hyper-nuclei

Jets

Heavy-flavor hadrons

MTD

High pT muons Jets & Correlations

Charged hadrons

STAR PID for (π, K, p) Au+Au at 7.7 GeV Au+Au at 39 GeV Au+Au at 200 GeV

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 7.7 GeV

STAR Preliminary

π TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 7.7 GeV

STAR PreliminaryK TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 7.7 GeV

STAR Preliminaryp TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 39 GeV

STAR Preliminary

π TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 39 GeV

STAR Preliminary

K TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

0.5

1

1.5

2

2.5

3

3.5

4Au+Au 39 GeV

STAR Preliminaryp TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

1

2

3

4

5

6Au+Au 200 GeV

STAR Preliminaryπ TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

1

2

3

4

5

6

Au+Au 200 GeV

STAR Preliminary

K TPC

Rapidity-1 -0.5 0 0.5 1

(G

eV

/c)

Tp

0

1

2

3

4

5

6Au+Au 200 GeV

STAR Preliminary

p TPC


STAR Detector Configurations

  STAR: Large coverage, excellent PID, fast DAQ - detects nearly all particles produced at RHIC - multiple fold correlation measurements - Probes: bulk, penetrating, and bulk-penetrating

  STAR: Perfect mid-y collider experiment

  STAR: Expanding into forward rapidity regions

Period Detectors Physics 2001-2010 TPC u, d, s 2010 TPC + TOF u, d, s + dilepton 2013 TPC + TOF + MTD u, d, s, c, b +

dilepton 2014 TPC + TOF + MTD + HFT


(1) Hadron Spectra

STAR Preliminary

√sNN = 39 GeV Au+Au Collisions


Bulk Properties at Freeze-out

Kinetic Freeze-out: -  Central collisions => lower value of Tkin and larger collectivity β

-  Stronger collectivity at higher energy

Chemical Freeze-out: (GCE) - Centrality dependence in Tch and µB

-  The effect seems stronger at lower energy.


(2) BES Dependence Dielectrons

1)  Low mass reg. (Mee ≤ 1GeV): no obvious energy dependence in the ratio of data/cooktail. At 19.6, the ratio is consistent with SPS results.

2)  Intermediate mass reg. (1 ≤ Mee ≤ 3GeV): clear energy dependence, correlated charm? Thermal radiation, ~exp(-Mee/T)?

√sNN

200 GeV

62.4 GeV

39 GeV

ω ϕ

J/ψ


BES Dependence of Di-electrons

1)  With in-medium broadened rho, model results are consistent with experimental data (mee ≤ 1 GeV/c2) at √sNN = 200, 62.4, 39, 27 and 19.6GeV

2)  In Au+Au collisions at 200GeV, the centrality and pT dependence results on data/hadronic cocktails (mee ≤ 1 GeV/c2) understood with current model calculations


(3) NCQ Scaling in v2

-  mφ ~ mp ~ 1 GeV -  ss ➯ φ not K+K- ➯ φ -  σφh << σpπ, ππ

In the hadronic case, no number of quark scaling and the value of v2 of φ will be small.

* Thermalization is assumed!

➠

0 0.5 1 1.5

0

0.02

0.04

0.06

0.08

0.1

!

sK

"

#

K

p

(a) Default

0 0.5 1 1.5

(b) String Melting

)2 (GeV/cq

)/n0-mT

(m

q/n

2v

|<1$AMPT, Au+Au, 9.2GeV, b<14fm, |

➠


Collectivity v2 Measurements

(GeV)NNs0 20 40 60

)X( 2

(X)-v

2v

0

0.02

0.04

0.06

0.08Au+Au, 0-80%-sub EPη

+Ξ--Ξ

pp-Λ-Λ --K+K

-π-+π

1) Number of constituent quark (NCQ) scaling in v2 => partonic collectivity => deconfinement in high-energy nuclear collisions

2) At √sNN < 11.5 GeV, the v2 NCQ scaling is broken, indicating hadronic interactions become dominant.

2v

0

0.1

0.211.5 GeV a)

p�

-�

-�

+�+Ks0K

�

0 1 2 3

(B)-

fit2v 0

0.05

62.4 GeV b)

Au+Au, 0-80%

0 1 2 3

0-mTm

11.5 GeV c)

p�

+�

+�

-�-Ks0K

�

0 1 2 3)2 (GeV/c

62.4 GeV d)

-sub EP�

0 1 2 3

STAR: Phys. Rev. Lett. 110 (2013) 142301


BES v2 and Model Comparison

0

0.01

0.02

0.03

0.04

0 100 200 300 400

pR

K/

Exp. data Hydro model

p

K

/

MB Au + Au Collisions at RHIC

Baryonic Chemical Potential µB (MeV)

200 62.4 39 27 19.6 11.5 7.7 3sNN (GeV)

v 2(pa

rt.) -

v2(

anti-

part.

)

0 100 200 300 400

RV=0.5

RV=1.1

pR

K/

Exp. data NJL model

200 62.4 39 27 19.6 11.5 7.7 3sNN (GeV)

(b)(a)//STAR

//11 BESII//References//plot1_D

v2_2013.kumac//

(a) Hydro + Transport: consistent with baryon results. [J. Steinheimer, V. Koch, and M. Bleicher PRC86, 44902(13).]

(b) NJL model: Hadron splitting consistent. Sensitive to vector-coupling and net-baryon density dependent. [J. Xu, T. Song, C.M. Ko, and F. Li, arXiv:1308.1753]


(4) Higher Moments 1) High moments for conserved quantum numbers:

Q, S, B, in high-energy nuclear collisions

2) Sensitive to critical point (ξ correlation length):

3) Direct comparison with calculations at any order:

4)  Extract susceptibilities and freeze-out temperature. An independent/important test on thermal equilibrium in heavy ion collisions.

References: - A. Bazavov et al. 1208.1220 (NLOTE) // STAR: PRL105, 22303(2010) // M. Stephanov: PRL102, 032301(2009) // R.V. Gavai and S. Gupta, PLB696, 459(2011) // S. Gupta, et al., Science, 332, 1525(2011) // F. Karsch et al, PLB695, 136(2011) // S.Ejiri etal, PLB633, 275(06) // M. Cheng et al, PRD79, 074505(2009) // Y. Hatta, et al, PRL91, 102003(2003)

€

δN( )2 ≈ ξ2, δN( )3 ≈ ξ4.5, δN( )4 ≈ ξ7

S *σ ≈χB3

χB2 , κ *σ 2 ≈

χB4

χB2


0.20.40.60.81.01.2 Au+Au Collisions at RHIC

Net-proton<0.8 (GeV/c),|y|<0.5

T0.4<p

Skellam Distribution70-80%0-5%

0.4

0.6

0.8

1.0

1.2

p+p dataAu+Au 70-80%Au+Au 0-5%Au+Au 0-5% (UrQMD)

5 6 7 8 10 20 30 40 100 2000.85

0.90

0.95

1.00

1.05

mS

2m

g)/S

kella

mm

(S

(GeV)NNsColliding Energy

STAR net-proton results:

1)  All data show deviations below Poisson beyond statistical and systematic errors in the 0-5% most central collisions for κσ2 and Sσ at all energies. Larger deviation at √sNN ~ 20GeV

2)  Independent p and pbar production reproduces the observed energy dependence of κσ2 and Sσ

3)  UrQMD model show monotonic behavior in the moment products

4)  Higher statistics needed for collisions at √sNN < 20 GeV. BES-II is needed.

STAR: 1309.5681

Net-proton Higher Moments BES-II RHIC

BES-I


BES-II: e-cooling, iTPC Upgrades A. Fedotov, W. Fischer, 2012

√sNN (GeV) ~ 5 ~ 20 Increasing factor 3-5 10

1) BES-II at √sNN < 20 GeV

2) RHIC e-cooling will provide increased luminosity ~ x3 - 10

3) STAR iTPC upgrade extend mid-rapidity coverage – beneficial to several crucial measurements

Relativistic Gamma

Lum

inos

ity 1

/(sec

.cm

2 )

iTPC Upgrade: |η| ≤ 1.1 |η| ≤ 1.7 i) Crucial for BES-II ii) Important for eSTAR


Part I: Summary

(1)  In high-energy nuclear collisions, √sNN ≥ 200 GeV, hot and dense matter, with partonic degrees of freedom and collectivity, has been formed

(2) RHIC BES-I: [partonic] < µB ~ 110 (MeV) ( √sNN ≥ 39 GeV ) [hadronic] > µB ~ 320 (MeV) ( √sNN ≤ 11.5 GeV )

(3) RHIC BES-II: focus at √sNN ≤ 20 GeV region with higher luminosity (x10) + detector upgrade iTPC: Run18 (2017)


0

0.5

1

1.5

0 2 4 6 80

0.5

1

1.5

0 2 4 6 8

quark-gluon plasma

hadronic phase

(TC = 175 MeV)

Baryon Chemical Potential µB/TC

Tem

pera

ture

T/T

C//m

odels/kurtosis4Science/figure/tmu_dl_15July2012.kum

ac//LHC SPS AGS SIS

RHICFAIR/NICA

Chemical freeze-out*

2 TE RHIC, SPS, FAIR

3

3 Phase boundary RHIC, FAIR/NICA

Exploring QCD Phase Structure

1

1 Tini, TC LHC, RHIC

2

Part

onic

Mat

ter

Had

roni

c M

atte

r

LHC+RHIC sQGP properties √sNN ~ 0.05 - 5 TeV

RHIC BES-II QCD phase

structure and critical point √sNN ≤ 20 GeV

Future EIC Cold nuclear

matter properties

e + ion collisions

RHIC+FAiR Quarkyonic? √sNN ≤ 12 GeV


eSTAR: The Future of RHIC eSTAR: A Letter of Intent

The STAR Collaboration

October 1, 2013

0

0.5

1

1.5

0 2 4 6 80

0.5

1

1.5

0 2 4 6 8

quark-gluon plasma

hadronic phase

(TC = 175 MeV)


Tem

pera

ture

T/T

C

//models/kurtosis4Science/figure/tm

u_dl_15July2012.kumac//

LHC SPS AGS SIS

RHICFAIR/NICA


Hot QCD Matter

Cold QCD Matter gluon degrees of freedom dominant


Part II

Study Quarkonia Production at RHIC and LHC

Yunpeng Liu1, Zebo Tang2, Kai Zhou3, NX4, Pengfei Zhuang3

1: Texas A&M, USA 2: USTC, Hefei, China 3: Tsinghua University, Beijing, China 4: CCNU and LBNL, China/USA

0

0.5

1

1.5

0 2 4 6 80

0.5

1

1.5

0 2 4 6 8

quark-gluon plasma

hadronic phase

(TC = 175 MeV)


Tem

pera

ture

T/T

C//m

odels/kurtosis4Science/figure/tmu_dl_15July2012.kum

ac//

LHC SPS AGS SIS

RHICFAIR/NICA


2 TE RHIC SPS, FAIR 1 Tini, TC

LHC, RHIC 3 Phase Boundary

RHIC, FAIR/NICA

The QCD Phase Diagram and High-Energy Nuclear Collisions

1 2 3

heavy quark (hq): clean, penetrating, bulk probes for studying the

sQGP medium properties


Why Heavy Quark? Mass Matters: -  Heavy quark masses are not

altered in QCD medium -  Negligible thermal production

in collisions

 Tool for studying properties of the hot/dense medium at the early stage of collisions

Heavy quark collectivity Thermalization Deconfinement

B. Mueller, arXiv: 0404015 X. Zhu, et al, PLB647, 366(2007)

1

10

10 2

10 3

10 4

10 5

1 10 102

103

104

105

1

10

10 2

10 3

10 4

10 5

1 10 102

103

104

105

Total quark mass (MeV)

Hig

gs q

uark

mas

s (M

eV)

t

bc

s

d

u

QCD Vacuumχc symmetry breaking

Higgs VacuumElectroweak symmetry breaking

/Models/00_jpsi_Science/plot2_qcd_m

ass_dec2011


Key Effects

(GeV)s10 210 310 410

b)µ ( cc

m

1

10

210

310

410

510 b)µ ( bb

m

1

10

210

310

410

510SPS/FNAL/HERA-B (pA)PHENIX (pp, AuAu)STAR (pp, dAu, AuAu)

)pUA1 (pALICE (pp)ATLAS (pp)LHCb (pp)

NLO (MNR)

cc

bb

FONLL

0.4

0.6

0.8

1

1.2

10-3

10-2

10-1

1

RH

IC(<y>=0)

RH

IC(<y>=1.7)

LHC

(<y>=0)

Gluon Distribution Function (EKS89)

Q2 = 13 GeV2

Q2 = 2 GeV2

Momentum Fraction xBJ

RPbG

(x, Q

2 )

/Models/00_jpsi_Science/plot4_pdf_15june2012/

L (fm)0 1 2 3 4 5 6 7 8 9 10

]2 [(

GeV

/c)

� 2 T p�

1

2

3

4

5

L (fm)0 1 2 3 4 5 6 7 8 9 10

NA50, 27.4 GeV (pA)NA3/NA38, 19.4 GeV (pA, OA, SU)NA50, 17.2 GeV (PbPb)NA60, 17.2 GeV (InIn)PHENIX, 200 GeV (pp, dAu)PHENIX, 200 GeV (CuCu)PHENIX, 200 GeV (AuAu)PHENIX (forward), 200 GeV (pp, dAu)PHENIX (forward), 200 GeV (CuCu)PHENIX (forward), 200 GeV (AuAu)

partN1 2 3 4 5 10 20 100 200

SPS

RHIC

Cold Matter Effects: 1)  Npdf: shadowing effect 2)  Production cross-sections 3)  Cronin effect

Hot Matter Effects: 1)  Debye screening 2)  Regeneration


In Nucleus-Nucleus Collisions

1

� J/

Surv

ival

Pro

babi

lity

�(2S) �(1P)

(2S)(1P) (1S)

(1S)�

Energy Density

J/

Pro

duct

ion

Prob

abili

ty�

1

Energy Density

thermal dissociation

exogamous regeneration

Sequential Suppressions Regenerations

Matsui & Satz, PLB178, 178(1986).

Debye Screening:

1)  Total # of J/ψ reduces 2)  Sensitive to hot/dense medium

€

J /ψ →c + c_

rJ /ψ ≥ λD ≈1

g T( ) • T

At the boundary of hadronizatipn:

1)  Total # of J/ψ increases 2)  Sensitive to hot/dense medium

€

c + c_→J /ψ

A. Adronic, et al, PLB652, 659(2007).


1) Traditional RAA depends on the (TMD) pT integrated yields. Sensitive to Npdf* and model dependent parameter nbin.

2) The TMD dependent rAA(pT2) ＊＊

more sensitive to dynamical medium effects including Cronin effect, Debye Screening, and Regeneration.

＊ H. Satz, arXiv: 1303.3493 ＊＊ Kai, Xu, Zhuang, NPA834, 249(2010)

Modification Factors

€

RAA =N AA

nbinAA N pp

rAA(pT2 ) =

pT2 AA

pT2 pp

TMD: transverse momentum distribution


Charm Production at RHIC

QM 2011, QM 2012

He, et al. arXiv: 1204.4442; Gossiaux, et al. arXiv: 1207.5445 Where is the true QCD medium effect?

Open Charm: (1)  Initial production

follows binary collisions

(2)  Suppressed at pT> 3GeV/c.

J/ψ: (closed Charm) (1)  Suppressed in more

central collisions. Similar observations at LHC

(2)  Near zero v2.


Charm Interactions with Medium

0

0.5

1

1.5

2

PHENIX /0, PRL96, 202301(96)STAR KS

0, PRL108, 72302(12)STAR D0, QM12

0.2 0.5 1 2 5 10 20

Transverse Momentum pT (GeV/c)

Mod

ifica

tion

Fact

or R

AA 1)  As for light-quark hadrons, charm-quark hadrons show suppression at intermediate pT region: energy loss of hq!

2)  At LHC, charm-quark hadrons show non-zero collectivity: strong interactions among hq and the hot/dense medium.

RHIC

LHC


Onia Production in HI Collisions

Pythia* heavy-quark

Cold QCD effects Shadowing, Cronin

Hot QCD effects Debye screening

Energy loss

Regeneration

pT broadening (for all hadrons)

-  pT decreasing -  thermalization

(hq hadrons)

Hydro + Transport

Hadronization

(GeV)s10 210 310 410

b)µ ( cc

m

1

10

210

310

410

510 b)µ ( bb

m

1

10

210

310

410

510SPS/FNAL/HERA-B (pA)PHENIX (pp, AuAu)STAR (pp, dAu, AuAu)

)pUA1 (pALICE (pp)ATLAS (pp)LHCb (pp)

NLO (MNR)

cc

bb

FONLL

0 50 100 150 200 250 300 350

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4

pNumber of Participant N

0 50 100 150 200 250 300 3500 50 100 150 200 250 300 350

NA50/60, 17.2 GeV, 0<y<1PHENIX, 200 GeV, |y|<0.35ALICE Prel., 2760 GeV, |y|<0.9

(a) mid-rapidity

0 50 100 150 200 250 300 350

PHENIX, 39/62 GeV, 1.2<|y|<2.2PHENIX, 200 GeV, 1.2<|y|<2.2ALICE Prel., 2760 GeV, 2.5<|y|<4

(b) forward rapidity 0

0.5

1

1.5

0 100 200 300 400

(a) mid-rapidity J/^

Model predictions

SPS: Pb+Pb at 3sNN = 17.3 GeVRHIC: Au+Au at 3sNN = 200 GeVLHC: Pb+Pb at 3sNN = 2760 GeV

Number of Participants Npart

r AA(p

2 T) =

<p2 T>

AA/<

p2 T>pp

SPS

RHIC

LHC

0 100 200 300 400

(b) forward-rapidity J/^

Pb+Pb at 3sNN = 17.3 GeVAu+Au at 3sNN = 200 GeVPb+Pb at 3sNN = 2760 GeV

Experimental data

RHIC

LHC

/Models/00_jpsi_Science/plot2_ptraa_22dec2011/

σhf RAA rAA


0

20

40

60

80

100

0 100 200 300 400

Pb+Pb at √s−−NN = 2.76 TeVAu+Au at √s−−NN = 200 GeV

|y| < 0.9

2.5 < y < 4

|y| < 0.35

1.2 < y < 2.5


f regJ/Ψ (%

)/M

odels/00_jpsi_Science/plot2_freg_062012/

Driven by the initial heavy quark production cross-sections, much larger fraction of J/ψs are formed via regeneration, at hadronization, at LHC than that from RHIC!


T.M.D.: Charmonium Production

0

0.5

1

1.5

0 100 200 300 400

(A) mid rapidity

Model predictions

SPS: Pb+Pb at √sNN = 17.3 GeVRHIC: Au+Au at √sNN = 200 GeVLHC: Pb+Pb at √sNN = 2760 GeV


r AA(p

2 T) =

<p2 T>

AA/<

p2 T>pp

SPS

RHIC

LHC

0 100 200 300 400

(B) forward rapidity

Pb+Pb at √sNN = 17.3 GeVAu+Au at √sNN = 200 GeVPb+Pb at √sNN = 2760 GeV

Experimental data

RHIC

LHC


1)  LHC: large fraction of final J/ψs produced via regeneration leads to lower value of <pT>

2)  SPS: all final J/ψs are survivors. Increase of <pT> due to the initial Cronin scatterings

3)  RHIC: mixture of initial and regenerated J/ψs


J/ψ v2 Results

(1) J/ψ v2 is consistent with zero for MB Au+Au collisions at RHIC.

(2) At LHC energy, finite value of the J/ψ v2 is seen at the forward-y. Larger v2 is predicted for mid-y J/ψs.

Stronger regeneration effect at LHC!

Hydro model calculations failed.


0

0.5

1

1.5

0 100 200 300 400

(A) J/Ψ

Pb+Pb at √s−−NN = 17.3 GeVAu+Au at √s−−NN = 200 GeV

Experimental data


RAA

(p2 T)

= <

p2 T>AA

/<p2 T>

ppSPS

RHIC

LHC

0 100 200 300 400

(B) Υ

Model predictionRHIC: Au+Au at √s−−NN = 200 GeVLHC: Pb+Pb at √s−−NN = 5500 GeV

RHIC

LHC


(A) J/ψ productions at SPS, RHIC and LHC (B) Upsilon production: - RHIC: negligible regenerations, Cronin effect dominant. - LHC: sizable contributions from regenerations.

T.M.D.: Quarkonia Production


Regeneration at Low pT Region

Coalescence J/ψ concentrate at the small transverse momenta: from low pT charm quarks and lower averaged J/ψ <pT> and <pT

2>. Initial shadowing effect is small on rAA.

At LHC: Deconfinement and Thermalization of charm quarks!


(1)  In high-energy collisions, transverse momentum distributions (TMD) are important!

(2) The effects of Debye Screening and Regeneration are opposite for quarkonia production. They are all medium effects.

(3) J/ψ production showing by rAA(pT2), demonstrated

the influence of Debye screening and the regeneration, implying the formation of the hot/dense medium, the QGP, at RHIC and LHC. At LHC: charm quarks are consistent with the scenario of thermalization.

Part II: Summary

Thank you!

study qcd phase diagram in high-energy nuclear collisions · nu xu “new frontiers in qcd ... dec....

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