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
!32018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
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
!42018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
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
!52018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
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
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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
!72018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
[GeV/c]T
p0 2 4 6 8 10
pAu
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
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
!82018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
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
!92018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
partN0 100 200 300 400
pA,A
A(1
S+2S
+3S)
Rϒ
0.2
0.4
0.6
0.8
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
0.4
0.6
0.8
1
1.2
uncertaintycollN
STAR Preliminary
partN0 100 200 300 400
pA, A
AR
0
0.2
0.4
0.6
0.8
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
!102018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
partN0 100 200 300 400
AA
(1S)
Rϒ
0
0.2
0.4
0.6
0.8
1
1.2
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
0.4
0.6
0.8
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
!112018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
partN0 100 200 300 400
AA
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4 30-60% 10-30% 0-10%
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
(3S): CMS [email protected] TeV, |y|<2.4ϒ
uncertaintycollN
STAR Preliminary
uncertaintycollN
95% C. L.
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
(3S): CMS [email protected] TeV, |y|<2.4ϒ
(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
!122018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
[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
0.2
0.4
0.6
0.8
1
1.2
1.4 30-60% 10-30% 0-10%
uncertaintycollN
(1S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(1S): CMS [email protected] TeV, |y|<2.4ϒ
Rothkopf STAR CMS
STAR Preliminary
partN0 100 200 300 400
AA
(1S)
Rϒ
0
0.2
0.4
0.6
0.8
1
1.2
1.4 30-60% 10-30% 0-10%
uncertaintycollN
(1S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(1S): CMS [email protected] TeV, |y|<2.4ϒ
Rapp STAR CMS
STAR Preliminary
𝚼(2S+3S) suppression
!132018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
[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
0.8
1
1.2
1.4 30-60% 10-30% 0-10%
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
uncertaintycollN
STAR Preliminary
Rothkopf STAR CMS
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
partN0 100 200 300 400
AA
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4 30-60% 10-30% 0-10%
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
uncertaintycollN
STAR Preliminary
Rapp STAR CMS
(2S+3S): STAR Au+Au@200 GeV, |y|<0.5ϒ
(2S): CMS [email protected] TeV, |y|<2.4ϒ
Summary
!142018/11/04 Qian Yang @ ATHIC 2018, November 3th - 6th 2018, USTC
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
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