Quarkonium measurements in heavy-ion collisions at the ... · 0 2 4 6 8 10 pAu R 0 0.2 0.4 0.6 0.8...

Quarkonium measurements in heavy-ion collisions at the STAR

experiment

Qian Yang （杨钱） (for the STAR Collaboration)

Shandong University

2018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC �1

Outline

!22018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC

Motivation

STAR experiment

J/ψ measurements in p+Au collisions

𝚼 measurements in p+Au and Au+Au collisions

Summary

Quarkonium: sensitive probe to QGP


Heavy quarkonium: heavy mass (mc = ~1.5 GeV/c2, mb = ~ 4.5 GeV/c2) ➜ early creation.

long lifetime

Quarkonium is a sensitive probe of the deconfinement in the QGP: color screening dissociation

Cold nuclear matter effects


nPDF effect - Modification of gluon distributions in nucleus - Shadowing and Anti-shadowing

Shadowing

Anti-shadowing

Nuclear absorption effect - Break-up of quarkonium by remnant of incident nuclei.

Co-mover effect - Break-up of quarkonium by co-moving hadrons outside of nuclear remnant.

J/ψ

Hadron

J/ψ

𝚼: a cleaner probe at RHIC


𝚼 is a cleaner probe at RHIC: Regeneration is expected to be small

[A. Emerick, X. Zhao and R. Rapp: EPJ A48, 72 (2012)] [X. Du, M. He, and R. Rapp: PRC 96, 054901 (2017)]

Co-mover absorption is expected to be small for 𝚼(1S) [Z. Lin and C. Ko: PLB 503, 104 (2001)]

𝚼(1S)

𝚼(2S)

𝚼(3S)

QGP “Thermometer”

+ ➜

QGP

The Solenoidal Tracker at RHIC


TPC Tracking (momentum measurement, identification) (|𝝶| < 1, 0< 𝝋 < 2𝞹)

BEMC Trigger and identification of high-pT electrons (|𝝶| < 1, 0< 𝝋 < 2𝞹)

MTD Dimuon trigger and muon identification (|𝝶| < 0.5, 45% in 0< 𝝋 < 2𝞹)

J/ψ and 𝚼 ➔ µ+ + µ- : TPC + MTD 𝚼 ➔ e+ + e- : TPC + BEMC

Inclusive J/ψ RpA at √sNN = 200 GeV


[GeV/c]T

p0 2 4 6 8 10

pAu

R

0

0.2

0.4

0.6

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1

1.2

1.4

1.6

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2 |y|<0.5 0-100%pAuSTAR R

STAR Global uncertainty

=4.2mb Ferreiro et al.absσ nDSg + dAuR EPS09NLO Ma & VogtpAuR EPS09NLO Lansberg & ShaodAuR nCTEQ15 Lansberg & ShaodAuR

STAR Preliminary

Model calculations with only nPDF effect can touch upper limit of data within uncertainties. Data favor nPDF effects with additional nuclear absorption.

EPS09+NLO, Ma & Vogt, Private Comm. nCTEQ, EPS09+NLO, Lansberg Shao, Eur.Phys.J. C77 (2017) no.1, 1Comp. Phys. Comm. 198 (2016) 238-259 Comp. Phys. Comm. 184 (2013) 2562-2570

Inclusive 𝚼 RpA at √sNN = 200 GeV


ϒy

2.5− 2− 1.5− 1− 0.5− 0 0.5 1 1.5 2 2.5

)dA

u(R

pAu

(1S+

2S+3

S) R

ϒ

0

0.5

1

1.5

2

2.5

pAuSTAR preliminary R

dAuSTAR published RPHENIX

Shadowing, EPS09 (Vogt)

)eEnergy Loss (Arleo, Peign

Energy Loss + EPS09

common norm. Syst.pAuSTAR R common norm. Syst.dAuSTAR R

common norm. Syst.dAuPHENIX R

STAR Preliminary

Indication of 𝛶(1S+2S+3S) suppression in p+Au collisions ➜ Cold nuclear matter effects: RpA (|y|<0.5): 0.82 ± 0.10 (stat.) (sys.) ± 0.10 (global)- 0.07

+0.08

PHENIX: PRC 87 (2013) 044909STAR: PLB 735 (2014) 127

Inclusive 𝚼 RAA vs. Npart at √sNN = 200 GeV


partN0 100 200 300 400

pA,A

A(1

S+2S

+3S)

Rϒ

0.2

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1

1.2

1.4 30-60% 10-30% 0-10%

STAR Au+Au@200 GeV, |y|<0.5STAR p+Au@200 GeV, |y|<0.5

partN0 100 200 300 400

AA

(1S)

Rϒ

0

0.2

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1

1.2

uncertaintycollN

STAR Preliminary

partN0 100 200 300 400

pA, A

AR

0

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1

1.2

1.4 30-60% 10-30% 0-10%

(1S): Au+Au@200 GeV, |y|<0.5ϒ

(2S+3S): Au+Au@200 GeV, |y|<0.5ϒ

(1S+2S+3S): p+Au@200 GeV, |y|<0.5ϒ

uncertaintycollN

STAR Preliminary

(1S): Au+Au@200 GeV, |y|<0.5ϒ

(2S+3S): Au+Au@200 GeV, |y|<0.5ϒ

(1S+2S+3S): p+Au@200 GeV, |y|<0.5ϒ

𝚼(1S): Stronger suppression towards central collisions

𝚼(2S+3S): Stronger suppression in more central collisions More suppressed than 𝚼(1S) in 0-10% central collisions — sequential melting

Combination of dielectron and dimuon channels

𝚼(1S) suppression


partN0 100 200 300 400

AA

(1S)

Rϒ

0

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1.4 30-60% 10-30% 0-10%

(1S): STAR Au+Au@200 GeV, |y|<0.5ϒ

(1S): CMS [email protected] TeV, |y|<2.4ϒ

uncertaintycollN

STAR Preliminary

(GeV/c)T

p0 2 4 6 8 10

AA

(1S)

Rϒ

0

0.2

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0.6

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1

1.2

1.4STAR Au+Au@200 GeV (0-60%)

, |y|<0.5-µ+µ→(1S)ϒCMS [email protected] TeV (0-100%)

(1S), |y|<2.4 ϒ

STAR Preliminary

STAR Au+Au@200 GeV (0-60%), |y|<0.5-µ+µ→(1S)ϒ

CMS [email protected] TeV (0-100%)(1S), |y|<2.4 ϒ

𝚼(1S) suppression is similar at RHIC and LHC and no significant pT dependence: Medium temperature is higher at LHC due to higher collision energy Regeneration contribution is larger at LHC CNM Strong suppression of excited 𝚼 states that feed-down to 𝚼(1S)

CMS: PLB 770, 357 (2017)

𝚼(2S+3S) suppression


partN0 100 200 300 400

AA

R

0

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1

1.2

1.4 30-60% 10-30% 0-10%

(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ



uncertaintycollN

STAR Preliminary

uncertaintycollN

95% C. L.




(GeV/c)T

p0 2 4 6 8 10

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4STAR Au+Au@200 GeV (0-60%)

, |y|<0.5-µ+µ→(2S+3S)ϒCMS [email protected] TeV (0-100%)

(2S), |y|<2.4ϒ

STAR Preliminary

STAR Au+Au@200 GeV (0-60%), |y|<0.5-µ+µ→(2S+3S)ϒ

CMS [email protected] TeV (0-100%)(2S), |y|<2.4ϒ

STAR Preliminary

𝚼(2S+3S): • Indication of less suppression at RHIC than at LHC.

STAR: 𝚼(2S+3S) RAA: 0.35 ± 0.08 (stat.) ± 0.10 (sys.) (0 < pT < 10 GeV/c, 0-60%) CMS: 𝚼(2S) RAA: 0.08 ± 0.05 (stat.) ± 0.03 (sys.) (0 < pT < 5 GeV/c, 0-100%)

𝚼(1S) suppression


[CMS: PLB 770, 357 (2017)] [B. Krouppa, A. Rothkopf, M. Strickland: PRD 97, 016017 (2018)] [X. Du, M. He, and R. Rapp: PRC 96, 054901 (2017)]

𝚼(1S) RAA: Both Rothkopf’s and Rapp’s models describe data

Rothkopf’s model: use a lattice-vetted heavy-quark potential Rapp’s model: use in-medium binding energies predicted by thermodynamic T-matrix calculations using internal-energy potentials, from lattice QCD

partN0 100 200 300 400

AA

(1S)

Rϒ

0

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1

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1.4 30-60% 10-30% 0-10%

uncertaintycollN



Rothkopf STAR CMS

STAR Preliminary

partN0 100 200 300 400

AA

(1S)

Rϒ

0

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1.4 30-60% 10-30% 0-10%

uncertaintycollN



Rapp STAR CMS

STAR Preliminary

𝚼(2S+3S) suppression


[CMS: PLB 770, 357 (2017)] [B. Krouppa, A. Rothkopf, M. Strickland: PRD 97, 016017 (2018)] [X. Du, M. He, and R. Rapp: PRC 96, 054901 (2017)]

𝚼(2S+3S) RAA : Rapp’s model describes data Rothkopf’s model calculation is slightly lower than data in 30-60%

partN0 100 200 300 400

AA

R

0

0.2

0.4

0.6

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1.2

1.4 30-60% 10-30% 0-10%



uncertaintycollN

STAR Preliminary

Rothkopf STAR CMS



partN0 100 200 300 400

AA

R

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1.4 30-60% 10-30% 0-10%



uncertaintycollN

STAR Preliminary

Rapp STAR CMS



Summary


p+Au collisions at √sNN = 200 GeV

• Indication of 𝚼 suppression • J/ψ RpA favors additional nuclear absorption effect on top of nPDF effect

Au+Au collisions at √sNN = 200 GeV The precision of 𝚼 measurements is improved by combining results of dielectron and dimuon channels from dataset taken in different years (2011, 2014 and 2016) 𝚼(1S):

• Indication of stronger suppression towards central collisions• Similar suppression as at LHC• Both models are consistent with data at RHIC and LHC

𝚼(2S+3S):• More suppressed than 𝚼(1S) in 0-10% — sequential melting• Indication of less suppression at RHIC than at the LHC

Quarkonium measurements in heavy-ion collisions at the ... · 0 2 4 6 8 10 pAu R 0 0.2 0.4 0.6 0.8...

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