Measurements of ϒ Production and Nuclear Modification Factor … · 2014-06-17 · June 17, 2014...
Transcript of Measurements of ϒ Production and Nuclear Modification Factor … · 2014-06-17 · June 17, 2014...
Measurements of ϒ Production and Nuclear Modification Factor at STAR
Anthony Kesich University of California, Davis
For the STAR Collaboration
Outline
• Motivation for measuring Upsilons • The Solenoidal Tracker At RHIC and its triggers • ϒ production cross section in p+p • ϒ production in d+Au • ϒ Nuclear Modification Factor in Au+Au • LHC Results • Conclusions
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Goal: Quarkonia states in A+A
Charmonia: J/Ψ, Ψ’, χc Bottomonia: ϒ(1S), ϒ(2S), ϒ(3S),χB Key Idea: Quarkonia Melt in the plasma
• Color screening of static potential between heavy quarks • Suppression of states is determined by TC and their binding energy • Lattice QCD: Evaluation of spectral functions ⇒ Tmelting
• Originaly proposed by Matsui & Satz (1986)
When do states melt?
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H. Satz, HP06
A .M
ocsy, Sum
mer Qua
rkon
ium W
orksho
p, BNL, 201
1
Quarkonia at RHIC
• A cleaner probe compared to J/Ψ • co-mover absorption → negligible • recombination → negligible
• σcc = ~800 µb • σbb= ~ 2µb
• Challenge: low rate, rare probe – Large acceptance detector – Efficient trigger
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Why do ϒ at RHIC instead of J/Ψ?
R. Arnaldi, arXiv:1211.2578v1 [n
ucl-‐e
x]
Regenera'on of J/ψ!
RHIC/AGS AUM 2014 - A. Kesich
STAR
EM Calorimeter • |η| < 1 • Full φ coverage • Electron ID via E/p • Event Triggering
Time Projection Chamber • |η| < 1 • Full φ coverage • Tracking and EID via Ionization
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Triggering on ϒ decays
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Level 0 Trigger (p+p,d+Au,Au+Au): • Hardware-based • Fires on at least one high tower
Level 2 Trigger (p+p,d+Au): • Software-based • Calculates:
• Cluster energies • Opening angle • Mass
High rejection rate allowed us to sample entire luminosity
ϒ in p+p 200 GeV
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)2 (GeV/ceem8 9 10 11 12 130
10
20
30
40
50
60
70 STAR p+p = 200 GeVs
|<0.5ee|y
- -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
+ -N (a)
∫L dt = 20.0 pb-1���
Nϒ(total)= 152±23(stat. + fit)
Phys
. Rev
. D 8
2 (2
010)
120
04
Sta?s?cal error reduced by a factor of 2!
3X
n=1
B(nS)⇥ d�(nS)
dy= 64± 10+14
�12 pb
For |y|<0.5:
arXiv:1312.3675 acc. by PLB
ϒ in d+Au 200 GeV
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∫L dt = 28.1 nb-1���
Nϒ = 46 ± 13 (stat. + fit)
)2 (GeV/ceem8 9 10 11 12 13
Cou
nts
0
5
10
15
20
25
30
35 - -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
>coll<N×p+p
+ -NSTAR d+Au = 200 GeVNNs
|<0.5ee|y
(b)
3X
n=1
B(nS)⇥ d�(nS)
dy= 12.2± 3.4+2.1
�1.9 nb
arXiv:1312.3675 acc. by PLB
ϒ in p+p 200 GeV, Comparisons
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ϒy
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
/dy
(pb)
σd× - l+ lB
(1S+
2S+3
S),
ϒ
0
20
40
60
80
100
120
140
160
180
200STAR
= 200 GeVNNs-l+l →(1S+2S+3S) ϒ
(a)
STARppdAu / 1000
PHENIXppdAu / 1000
R. VogtNLO pQCD CEM
ppdAu / 1000
STAR √s=200 GeV p+p ϒ+ϒʹ′+ϒʺ″→e+e- cross section compared to pQCD and world data trend
(GeV)s210 310
(pb)
y=0
/dy|
ϒσ
d⋅ B
-110
1
10
210
310 STAR, p+p, |y|<1.0CFS, p+AE605, p+ACCOR, p+pR209, p+p
R806, p+ppUA1, p+pCDF, p+
CMS, p+pNLO CEM, MRST HO,
=1µ, m/2 m=4.75 GeV/c
(1S+2S+3S)ϒ
STAR Preliminary
CEM: R
. Vogt, Ph
ys. R
ep. 462125, 2008
CSM: J.P. Lansberg and S. Brodsky, PRD
81, 051502, 2010
arXiv:1312.3675 acc. by PLB
RdAu vs Rapidity
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ϒy
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
dAu
(1S+
2S+3
S) R
ϒ
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2 (1S+2S+3S)dAuSTAR R
STAR p+p Syst. UncertaintyPHENIXShadowing, EPS09 (Vogt)
)eEnergy Loss (Arleo, PeignEnergy Loss + EPS09
(b)• STAR results
consistent with predictions and with unity except for mid-rapidity
• PHENIX results also consistent with predictions
• Indication of suppression at y=0 unexpected, but further studies needed
arXiv:1312.3675 acc. by PLB
Comparison to E772 Results
• Upsilon suppression in CM seen before at E772 • STAR results mostly in agreement with E772
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Mass Number (A)10 210
,
/2)
pdσ
A(
pAσ
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
2
ppσ
A/2
dAσ
scaling0.96A
C Ca Fe WAu
(a)
= 40 GeV, 0<y<1.05NNsE772 1S (pA), = 40 GeV, 0<y<1.05NNsE772 2S+3S (pA),
= 200 GeV, |y|<1.0NNsSTAR 1S (dAu),
Fx-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
α
0.7
0.8
0.9
1
1.1
1.2
1.3 = 40 GeVNNsE772 1S (pA),
= 40 GeVNNsE772 2S+3S (pA), = 200 GeVNNsSTAR 1S+2S+3S (dAu),
= 200 GeVNNsSTAR 1S (dAu),
(b)
arXiv:1312.3675 acc. by PLB arXiv:1312.3675 acc. by PLB
CMS Upsilon pPb Results
• Double ratio of excited states to the ground state
• Large to complete suppression in PbPb
• Slight relative suppression in pPb – Indication of
nuclear absorption or breakup?
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(1S)ϒ(2S)/ϒ (1S)ϒ(3S)/ϒ
pp(1
S)]
ϒ(n
s)/
ϒ /
[xP
b(1
S)]
ϒ(n
s)/
ϒ[
0
0.2
0.4
0.6
0.8
1
1.2
1.4CMS Preliminary
> 4 GeV/cµ
Tp
= 5.02 TeVNNspPb | < 1.93
CMµη|
= 2.76 TeVNNsPbPb | < 2.4
CMµη|
95% upper limit
JHEP 04 (2014) 103
ϒ in Au+Au 200 GeV
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)2 (GeV/ceem8 8.5 9 9.5 10 10.5 11 11.5 12
Cou
nts
0
50
100
150
200
250
300
350
= 200 GeVNNsAu+Au |<0.5, Run 10ee|y
- -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
>coll<N×p+p
+ -NSTAR Au+Au|<1.0ee = 200 GeV, |yNNs
0-60% centrality
Raw yield of ϒ→e+e- with |y|<1.0 = 254 ± 29 ∫L dt = 1075 µb-1
arXiv:1312.3675 acc. by PLB
ϒ in Au+Au 200 GeV, Centrality
June 17, 2014 RHIC/AGS AUM 2014 - A. Kesich 14 )2 (GeV/ceem
8 8.5 9 9.5 10 10.5 11 11.5 12
Cou
nts
0
20
40
60
80
100
120
140
= 200 GeVNNsAu+Au |<0.5, Run 10ee|y
- -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
>coll<N×p+p
+ -NSTAR Au+Au|<1.0ee = 200 GeV, |yNNs
0-10% centrality
(c)
)2 (GeV/ceem8 8.5 9 9.5 10 10.5 11 11.5 12
Cou
nts
0
10
20
30
40
50
60
= 200 GeVNNsAu+Au |<0.5, Run 10ee|y
- -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
>coll<N×p+p
+ -NSTAR Au+Au|<1.0ee = 200 GeV, |yNNs
30-60% centrality
(a)
)2 (GeV/ceem8 8.5 9 9.5 10 10.5 11 11.5 12
Cou
nts
0
20
40
60
80
100
120
140
= 200 GeVNNsAu+Au |<0.5, Run 10ee|y
- -+N+ +N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
>coll<N×p+p
+ -NSTAR Au+Au|<1.0ee = 200 GeV, |yNNs
10-30% centrality
(b)
• AuAu signal split into three centrality bins
• Grey curve indicates line shape if no suppression
arXiv:1312.3675 acc. by PLB
ϒ in Au+Au 200 GeV, RAA
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Mod
els
from
M. S
tric
klan
d an
d D
. Baz
ow, a
rXiv
:111
2.27
61v4
A
. Em
eric
k et
al.,
Eur
. Phy
s. J.
A48
(201
2) 7
2
• Consistent increase in suppression with greater Npart in both Au+Au and U+U • Strickland models predict temperature range of 428 MeV < T < 442 MeV
partN0 50 100 150 200 250 300 350 400
AA
,dA
(1S+
2S+3
S) R
ϒ
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
(1S+2S+3S)ϒSTAR = 200 GeVNNs |<1.0
ϒ|y
STAR Au+Au
STAR d+Au
STAR U+U (prelim)
p+p Stat.+Fit Uncertainty
Common Normalization Syst.
STAR Au+Au, Centrality IntegratedSTAR U+U, Cent. Integrated, Prelim
Strickland-Bazow ModelEmerick-Zhao-Rapp Model
(a)
arXiv:1312.3675 acc. by PLB
ϒ(1S) in Au+Au 200 GeV, RAA
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Mod
els
from
M. S
tric
klan
d an
d D
. Baz
ow, N
ucle
ar P
hysi
cs A
879
, 25-
58 (2
012
Y. L
iu, B
. Che
n, e
t. al
., ar
Xiv
:100
9.25
85
• RAA of ϒ(1S) is consistent with 1 in dAu and peripheral and mid-central AuAu • Indication of suppression consistent with model calculation in central AuAu
partN0 50 100 150 200 250 300 350 400
AA
,dA
(1S)
Rϒ
0
0.5
1
1.5
2
2.5
STAR Au+Au
STAR d+Au
p+p Stat.+Fit Uncertainty
Common Normalization Syst.
STAR Au+Au, Centrality Integrated
Strickland-Bazow Model
Liu-Chen Model
(1S)ϒSTAR = 200 GeVNNs |<1.0
ϒ|y
(c)
arXiv:1312.3675 acc. by PLB
CMS Upsilon PbPb Results
• CMS also sees increasing suppression with more central collisions
• Results are consistent with predictions within statistics
• Suppression level comparable to STAR
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PRL 109 (2012) 222301
LHC: RAA vs Rapidity
• LHC shows increased suppression at higher y – Unexpected and opposite of predictions
• Role of CNM or Regeneration? June 17, 2014 RHIC/AGS AUM 2014 - A. Kesich 18
Javier Castillo
Comparison with models – Transport
• RAA of inclusive Υ(1S) in Pb-Pb collisions at √sNN = 2.76 TeV
• A. Emerick et al., [EPJ A48 (2012) 72]– Transport model– Suppression of Υ resonances by the QGP
• Mainly of the higher mass states– Small regeneration component included– Feed down from higher mass states included– CNM included via an “effective” σABS = 0–2 mb
11
Model does not reproduce the strong rapidity dependence of the RAA and underestimates the Υ(1S) suppression at forward rapidity
• Stronger suppression of direct Υ(1S)?• Role of regeneration?• Role of CNM?
PbPb @ 2.76 TeV arXiv:1405.4493
⟩partN⟨0 50 100 150 200 250 300 350
AA
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Total Primordial Regenerated
-1bµ = 69 intL = 2.76 TeV, NNsALICE: Pb-Pb
> 0Tp < 4, y(1S), 2.5 < ϒInclusive
y-4 -3 -2 -1 0 1 2 3 4
AA
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Total Primordial Regenerated
> 0Tp(1S), ϒ = 2.76 TeV, inclusive NNsPb-Pb
, 0%-90% (open: reflected)-1bµ = 69 intLALICE: , 0%-100%-1bµ = 150 intLCMS:
CMS: PRL109 (2012) 222301arXiv:1405.4493
Binding Energy
• STAR and CMS quarkonia RAA results show suppression for all states measured
• Increased suppression with decreased binding energy as prediction by Debye screening
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Binding Energy (GeV)0 0.2 0.4 0.6 0.8 1 1.2 1.4
AA
R
0
0.2
0.4
0.6
0.8
1
1.2
(1S)ϒ0-10%Centrality
(2S+3S), 95% limitϒ0-60% Centrality
>5 GeV/cT
, pψJ/0-10% Centrality
STAR Inclusive Quarkonium Measurements = 200 GeV, |y|<1NNsAu+Au,
Raphael Granier de Cassagnac Quark Matter 2014, Darmstadt
Five quarkonia • The suppression of 5 quarkonia
was observed in PbPb – Well-ordered with binding energy – Inclusive bottomonia – Charmonia pT > 6.5 GeV + pT-inclusive J/ψ from ALICE less suppressed than at RHIC, calling for recombination
• Quarkonia melt in quark matter
41
Talks by Moon & Abdulsalam PRL109 (2012) 2220301,
PAS-HIN-12-014, PAS-HIN-12-007
Y(1S)
Y(2S) J/ψ
arXiv:1312.3675 acc. by PLB Raphael Granier de Cassagnac, QM14
Outlook
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8 9 10 11 12 130
20
40
60
80
100
120
140 STAR Prelminary = 200 GeVNNsAu+Au
|<0.5, Run 11ee
|y
0-60% Centrality
- -+N+ +N
+ -NComb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
ϒ + bIntegral of CB + DY + b
)2 (GeV/ceem8 9 10 11 12 130
50
100
150
200
250 STAR Prelminary = 500 GeVNNsp+p
|<0.5, 0<pT<10ee|y
- -+N+ +N
+ -N
Comb. Background (CB)
bCB + Drell-Yan + b
(1S+2S+3S)ϒ + bCB + DY + b
ϒ + bIntegral of CB + DY + b
Au+Au @ 200 GeV, 2011 • Same setup as in 2010 • ~2800 ub-‐1
Au+Au @ 200 GeV, 2014 • ~13.8 nb-‐1 sampled by MTD • MTD and HFT full installed
p+p @ 500 GeV, 2011 • High energy doubles Upsilon cross sec?on • Excited-‐to-‐ground ra?o • PT spectrum • Preliminary results available soon • ~22 pb-‐1
Outlook
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ϒ with STAR MTD
• A detector with long-MRPCs – Covers the whole iron bars and leave the gaps in between uncovered. – Acceptance: 45% at ||<0.5 – 122 modules, 1464 readout strips, 2928 readout channels
• Long-MRPC detector technology, electronics same as used in STAR-TOF • Run 2012 -- 10%; 2013 – 60%+; 2014 – 100%: ϒ via +-
22
MTD (MRPC)
PartN0 50 100 150 200 250 300 350
AA
R0
0.2
0.4
0.6
0.8
1-µ
+µ→(1S)ϒ
-µ+µ→(2S)ϒ
-µ+µ→(3S)ϒ
, |y|<0.5-e+e→(1S+2S+3S)ϒ
STAR Muon Telescope Detector Au+Au-1 p+p, 20 nb-160 pb
7
Intermediate Silicon Tracker:
single-sided double-metal silicon pad
sensors with 600 µm × 6 mm pitch
σr-φ: 170 µm σz: 1800 µm
radius: 14 cm X/X0 < 1.5 % See details at poster M-30 by Yaping Wang
The task of SSD and IST is to guide the track from TPC to the innermost PXL detector with high hit density.
Silicon Strip Detector:
existing detector with new faster electronics
double sided silicon strip modules with 95 µm pitch
σr-φ: 20 µm
σz: 740 µm
radius: 22 cm
X/X0: 1 %
HFT Design�
Qiu Hao
Heavy Flavor Tracker
Adapted from J. Bielcik, Hard Probes 2013
Conclusions
• Measured ϒ production in p+p, d+Au, and ���Au+Au collisions at 200 GeV
• Au+Au results consistent with 2S and 3S suppression
• d+Au results hint at additional suppression beyond model calculations – Further studies warranted
• New muon channel will enhance and compliment our electron measurements
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June 17, 2014 RHIC/AGS AUM 2014 - A. Kesich 23
Thank you