1 28 July – 6 August 2014, Kolymbari, Crete, Greece

STAR Highlight on Heavy Ion Physics

Shusu Shi for the STAR collaboration

Lawrence Berkeley National Laboratory

The 3rd International Conference on New Frontiers in Physics 2014

2 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  Introduction

Ø  STAR Detectors

Ø  Recent Results Ø  Top energy collisions at RHIC - Study the medium properties Ø  Beam Energy Scan at RHIC - QCD phase boundary and critical point

Ø  Summary/Outlook

Outline

3 28 July – 6 August 2014, Kolymbari, Crete, Greece

Large acceptance at mid-rapidity! Time Projection Chamber: Full azimuthal coverage, (|η|<1.0)

Excellent particle identification!

STAR Detectors

4 28 July – 6 August 2014, Kolymbari, Crete, Greece

2 2

2 2

y xy x

ε< − >

=< + >

v2 =< cos2ϕ >, ϕ = tan−1(pypx)

Elliptic flow => Ø  Initial spatial anisotropy (eccentricity ε) -> final momentum anisotropy v2 by interactions among constituents

Ø  Self-quenching with time Ø Sensitive to the early stages of the system evolution

Good probe of the early stage of the collision.

partonic hadronic

Elliptic Flow (v2)

5 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  RHIC delivered the U+U collisions in order to study geometry effects Ø  Tip-tip and body-body enhanced samples selected via ZDC-mult cut Ø  IP-Glasma model matches the data better Bjoern Schenke, et al. arXiv:1403.2232 Maciej Rybczyński, et. al. PRC87,044908(2013)

v2 in U+U Collisions

more overlapping fewer spectators

Dashed boxes are systematic errors

ZDC (%)

Slo

pe

6 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  Event-by-Event fluctuations ε3 -> v3 Ø  The number of constituent

quark scaling does not work for v3

Ø  Hydro inspired (nq)i/2, i=3, seems to work for 200 GeV collisions up to (mT-m)/nq ~ 1 GeV/c2

P. Huovinen, Phys. Lett. B503, 58 (2001) R. Lacey, J. Phys. G38, 124048(2011)

Triangular Flow v3

7 28 July – 6 August 2014, Kolymbari, Crete, Greece

0 2 4 6 8

-2dy

) (G

eV/c

)T

dp Tp/2ev

N/(N

2 d -710

-410

-110

210 )/2, |y| < 10D+0U+U 193 GeV (D0-80%

20]×0-10% [5]×10-40% [

40-80% [/2]

2]×+D* [0p+p D

Au+Au 200 GeV

for Au+Au 200GeV�binN�p+p Levy scaled by

for U+U 193GeV�binN�p+p Levy scaled by

STAR Preliminary

(a)

Transverse

0.51

1.52 40-80% (b)

STAR Preliminary

AA R0 D 0.5

11.5

2 10-40% (c)

0 2 4 6 8

0.51

1.52

0-10% (d)

(GeV/c)T

Momemtum ppT (GeV/c)

Au+Au@200 GeV: submitted to PRL, arXiv:1404.6185

D0 R

AA

Open Heavy Flavor

Particle production in A+A

Particle production in p+p

Average number of binary collisions in A+A

Ø  Large suppression at high pT indicates strong charm-medium interactions Ø  Enhancement at pT ~ 0.7-2 GeV/c: described by models with charm quark coalescence with light quarks

David Tlusty: August 6 [parallel 2]

8 28 July – 6 August 2014, Kolymbari, Crete, Greece

partN0 100 200 300 400

AA

R

00.20.40.60.8

11.21.41.61.8

2200 GeV theoretical curve62.4 GeV theoretical curve39 GeV theoretical curve

uncertaintycollNp+p uncertainty 62.4 GeVp+p uncertainty 39 GeVp+p 200 GeV(statistics)

Au+Au 200 GeV

Au+Au 62.4 GeV

Au+Au 39 GeV

U+U 193 GeV

Ø  Suppression increases with collision centrality Ø  Similar suppression in U+U and Au+Au collisions Ø  Weak beam energy dependence of J/ψ RAA X.B. Zhao et al., PRC82, 064905(2010) L. Yan et al., PRL97, 232301(2006)

J/ψ STAR Preliminary

Quarkonia

Barbara Trzeciak: August 2 [parallel 4]

9 28 July – 6 August 2014, Kolymbari, Crete, Greece

BES-I

Beam Energy Scan at RHIC

Data: 5% Au+Au collisionsA. Adronic, et al.J. Cleymans, et al.

10 100 10000

50

100

150

200

Tem

pera

ture

Tch

(MeV

)

Baryonic Chemical Potential µB (MeV)

Au+Au Collisions at RHIC //STAR//11 BESII//R

eferences//03/plot2_cfo_March2014.kum

ac//

LGT: S. Gupta, et al.LGT: Z. Fodor, et al.

(TC = 170 MeV)

Observables:

Phase boundary Charge separation; v2 - NCQ scaling 1st order phase transition Directed flow v1 Critical point Fluctuations Chiral symmetry restoration Di-lepton production

Statistical-Thermal Model

STAR Preliminary

√sNN (GeV) 7.7 11.5 14.5 19.6 27 39

µB (MeV) 420 315 260 205 155 115

Study QCD Phase Structure! Year 2014

Daniel McDonald: July 29 [FAIR workshop]

10 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  The difference between particles and anti-particles increases with decreasing beam energy – NCQ scaling breaks

Ø  Model comparison Ø  Hydro + Transport (UrQMD): consistent with baryon data Ø  Nambu-Jona-Lasino (NJL) model (partonic + hadronic potential): hadron splitting consistent

J. Steinheimer, V. Koch, and M. Bleicher PRC86, 44902(2013); J. Xu, et al., PRL112, 012301(2014)

0

0.01

0.02

0.03

0.04

0 100 200 300 400

pR

K/

Exp. data Hybrid model

p

K

/

0-80% Au + Au Collisions at RHIC

Baryonic Chemical Potential µB (MeV)

200 39 27 19.6 11.5 7.7 (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 39 27 19.6 11.5 7.7 (GeV)

(b)(a)

(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

Particle vs. Anti-particle v2

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

11 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  Hydro calculation with 1st order phase transition motivates the study

Ø  Net-proton slope changes sign twice EOS softest point? Ø  UrQMD fails to reproduce the data

Ø  BESII improvement: Improved reaction plane determination

Systematic centrality-dependent analysis STAR: PRL112, 162301(2014) H. Stoecker, NPA750, 121(2005)

Directed Flow v1: Softest Point

dv1/dy: the slope of directed flow versus rapidity near mid-rapidity

12 28 July – 6 August 2014, Kolymbari, Crete, Greece

SS -

OS

Ø  H: CME contributions A. Bzdak et al., Lect. Notes Phys. 871, 501 (2013)

è Disappears at low energy hadronic interactions become dominant at √sNN ≤ 11.5 GeV D. Kharzeev. PLB633, 260 (2006) D. Kharzeev, et al. NPA803, 227(2008) (GeV)NNs

10 210 310

4 1

0×

) O

S -

HSS

(H

-1

0

1

2 30 - 60%

= 1g = 1.5g = 2g

BES II error projection

Au+Au Pb+Pb

STAR: PRL 113, 052302 (2014)

Charge Separation wrt Event Plane Chiral Magnet Effect + Local Parity Violation

STAR: PRL. 103, 251601(2009)

13 28 July – 6 August 2014, Kolymbari, Crete, Greece

0.4

0.6

0.8

1

[

[

[

[ [

[

[

[

[

[

[

[ [

[

Net

-pro

ton gm

2

(a) STAR net-proton data70 - 80% 0 - 5%

(|y|<0.5; 0.4<pT<0.8(GeV/c))

UrQMD (0 - 5%)Poisson

BESII error

-10

0

10

[

[

[

[

[

[

[

[

[

[

[

[ [ [

Net

-cha

rge gm

2

10 20 505 100 200

Colliding Energy 3sNN (GeV)

(b) STAR net-charge data70 - 80% 0 - 5%

(|d|<0.5; 0.2<pT<2.0(GeV/c))

NBD (0 - 5%)Poisson

Au + Au Collisions at RHIC

Non-monotonic behavior would be indicative of existence of CP Net-proton results:

Ø  Deviations below Poisson for κσ2 at all energies. Relatively larger deviation at √sNN~20GeV

STAR: PRL112, 32302(2014)

Net-charge results:

Ø  No non-monotonic behavior Ø  More affected by resonance

decays

STAR: arXiv: 1402.1558

Higher statistics needed for collisions at √sNN < 20 GeV

Sensitive to critical point (ξ correlation length):

δN( )2 ≈ ξ 2, δN( )3 ≈ ξ 4.5, δN( )4 ≈ ξ 7

Sσ ≈χB3

χB2 ,κσ

2 ≈χB4

χB2

Higher Moments

14 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  Mee < 1.1 GeV/c2: Model results with in- medium broadened ρ are consistent with data.

Ø  1.1 < Mee < 3.0 GeV/c2: QGP thermal radiation Ø  BES-II: high statistics R. Rapp: PoS CPOD13, 008(2013)

200GeV

19.6GeV

Di-electrons

BES: STAR Preliminary 200 GeV: PRL 113, (022301) 2014

Clean and penetrating probe! Do not suffer from strong interactions

15 28 July – 6 August 2014, Kolymbari, Crete, Greece

Ø  Top Energy Heavy Ion Collisions - Initial Condition: U+U collisions: IP-Glasma results match data better - Hot and dense sQGP: Heavy flavor hadron RAA: large suppression for D mesons at high pT

Ø RHIC Beam Energy Scan Program √sNN ≥ 39 GeV: partonic interactions dominant √sNN ≤ 11.5 GeV: hadronic interactions dominant

Ø Outlook - Heavy flavor program with new upgrade Heavy Flavor Tracker and Muon Telescope Detector - RHIC BES-II: Focus on √sNN ≤ 20 GeV region

Summary/Outlook

2013 2014 2015 2016 2017 2018 2019

Charm; Di-lepton; sQGP properties

BESII HFT/MTD e-Cooling, iTPC

16 28 July – 6 August 2014, Kolymbari, Crete, Greece

Heavy Flavor Tracker (HFT) Physics goal: Precision measurement of heavy quark hadron production in heavy ion collisions

Collected 1.2 B Au+Au at 200 GeV events in year 2014

HFT and MTD

Muon Telescope Detector (MTD): Physics goal: Heavy Quarkonia – Upsilon states Took 12 nb-1 Au+Au collisions at 200 GeV in year 2014 for quarkonium physics

Both Fully installed in Run14!

Spyridon Margetus: August 5 [parallel 5]

17 28 July – 6 August 2014, Kolymbari, Crete, Greece

BES II Electron cooling + longer beam bunches for BES II factor 4-15 improvement in luminosity compared with BES I Detector upgrade Ø  Event Plane Detector important for flow and fluctuation analyses Ø  iTPC upgrade increases TPC acceptance to ~1.7 in η; improves dE/dx resolution Fixed target program extends STAR’s physics reach to region of compressed baryonic matter

With electron cooling and long beam bunches

With electron cooling

BES I performance

Grazyna Odyniec: August 4 [Plenary 5]