Upsilon Production in
Heavy Ions with STAR
and CMS
HIT Seminar
Berkeley Lab
September 18, 2012.
Manuel Calderón de la Barca Sánchez
Outline
• Bottomonium in heavy ion collisions
• Upsilon measurements in:
– STAR
– CMS
• Upsilon cross sections in p+p
• Upsilon nuclear modification factors
• Conclusions
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
2
Quarkonium in the QGP
• Heavy quarkonia:
– Heavy quark bound state
are probes of the hot
QCD medium
ϒ
– Debye screening
T=0
0<T<TC
TC<T
• Matsui & Satz, PLB 178 416 (1986)
– Sequential Suppression
• Digal et al., PRD 64 2001 094015
– Landau damping: Im V.
• (e.g. Laine et al., JHEP 03 2007 054)
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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High T: the interaction between the
heavy quarks is modified.
• Charmonium suppression:
longstanding QGP
signature
– Original idea: High T leads to
screening
– Screening prevents heavy
quark bound states from
forming.
– J/y suppression:
• Matsui and Satz, Phys. Lett. B 178
(1986) 416
– lattice calculations,
indications of screening
• Nucl.Phys.Proc.Suppl.129:560
-562,2004
– Note: Calculations of internal
energy or internal energy
9/18/12 HIT Seminar, Berkeley Lab
O. Kaczmarek, et al.,
Nucl.Phys.Proc.Suppl.129:560-562,2004
Manuel Calderón de la Barca Sánchez
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The heavy quark potential in QCD
• Recent news: Heavy quark potential from (quenched) Lattice QCD
– A.Rothkopf, et al. PRL 108 (2012) 162001
– Broadening due to collisions with medium (Im V) possibly more
important than screening (Re V).
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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Measuring the Temperature
Quarkonia’s suppression pattern
 QGP thermometer
Lattice QCD Calculations:
Dissociation temperatures of quarkonia states
hep-ph/0110406
• For  production at RHIC and LHC
– A cleaner probe compared to J/y
• co-mover absorption → negligible
• recombination → negligible
– d-Au: Cold Nuclear Matter Effects
• Shadowing / Anti-shadowing at y~0
• Challenge: low rate, rare probe
– Large acceptance detector
– Efficient trigger
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
A .Mocsy, 417th WE-Heraeus-Seminar,2008
• Expectation:
– (1S) no melting
– (2S) likely to melt
– (3S) melts
6
•
J/y Puzzles from SPS and
RHIC
Similar J/y suppression at the
SPS and RHIC!
– despite 10× higher √sNN
• Suppression does not increase
with local energy density
– RAA(forward)<RAA(mid)
• Possible ingredients
– cold nuclear matter effects
– sequential melting
– regeneration
• What happens for
bottomonium?
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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Charmonium vs Bottomonium
• J/y suppression
– Hot nuclear matter effects: Suppression? Regeneration? Co-mover
absorption? Energy loss? Flow?
• Bottomonium Expectations
– Cleaner probe of screening, deconfinement.
– Regeneration?
• Not a big role for bottomonium
• Open bottom: sbb ~ 1.34 – 1.84 mb.
• Open charm: scc ~ 551 – 1400 mb.
– Co-mover absorption?
• Expected to be small for bottomonium
• Charmonium sabs ~ 3 – 4 mb.
• Bottmonium sabs ~ 1 mb.
– Lin & Ko, PLB 503 104 (2001)
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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Upsilons in STAR
• Upsilons via Triggering, Calorimetry, Tracking,
and matching of tracks to calorimeter towers.
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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The CMS Detector
9/18/12 HIT Seminar, Berkeley
Lab
Manuel Calderón de la Barca Sánchez
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 in p+p 200 GeV in STAR
2006
2009
Phys. Rev. D 82 (2010) 12004
∫L dt = 19.7 pb-1
N(total)= 145±26(stat.)
∫L dt = 7.9 ± 0.6 pb-1
N(total)= 67±22(stat.)
STAR Preliminary
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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CEM: R. Vogt, Phys. Rep. 462125, 2008
CSM: J.P. Lansberg and S. Brodsky, PRD 81, 051502, 2010
 Comparison to NLO pQCD
• Comparison to NLO
• STAR √s=200 GeV p+p ++→e+e- cross
section consistent with pQCD Color
Evaporation Model (CEM)
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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 in p+p 7 TeV in CMS
PRD 83,
112004 (2011)
9/18/12 HIT Seminar, Berkeley Lab
• Excellent resolution at
midrapidity.
• Separation of 3 states.
Manuel Calderón de la Barca Sánchez
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 vs √s, World Data
STAR
Preliminary
STAR √s=200 GeV and CMS √s=7 TeV p+p
++→e+e- cross section consistent with pQCD and
world data trend
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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 in d+Au 200 GeV
STAR
Preliminary
Signal has ~8σ significance
pT reaches ~ 5 GeV/c
∫L dt = 32.6 nb-1
N+DY+bb(total)= 172 ± 20(stat.)
Final results on RdAu coming soon.
LHC pPb run in January/February.
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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 in Au+Au 200 GeV
Raw yield of
e+e- with |y|<0.5 = 197 ± 36
∫L dt ≈ 1400 µb-1
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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 in Au+Au 200 GeV, Centrality
STAR
Preliminary
STAR
Preliminary
Peripheral
9/18/12 HIT Seminar, Berkeley Lab
STAR
Preliminary
Central
Manuel Calderón de la Barca Sánchez
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Bottomonia at 2.76 TeV: 2010 data
pp
9/18/12 HIT Seminar, Berkeley Lab
PRL 107 (2011) 052302
Manuel Calderón de la Barca Sánchez
PbPb
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Bottomonia: 2011 data
pp
PbPbEvents / ( 0.1 GeV/c
2
)
800
700
600
500
400
300
200
100
0
7
Preliminary
CMS PbPb sNN = 2.76 TeV
Cent. 0-100%, |y| < 2.4
13
data
= 150 mb-1
12
PbPb fit
T
11
p > 4 GeV/c
10
Lint
m
9
pp shape
8
mm m (GeV/c 2)
14
Ratios not corrected for acceptance and efficiency
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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Models from M. Strickland and D. Bazow, arXiv:1112.2761v4
 in Au+Au 200 GeV, RAA
•Indications of Suppression of Upsilon(1S+2S+3S) getting stronger with centrality.
•Reduced pp statistical uncertainties, increased statistics from 2009 data vs 2006 data.
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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(2S)/(1S) Double Ratio, CMS
• Separated (2S) and (3S)
N¡ (2S) / N¡ (1S) PbPb
N¡ (2S) / N¡ (1S)
pp
N¡ (3S) / N¡ (1S) PbPb
N¡ (3S) / N¡ (1S)
= 0.21± 0.07 ± 0.02
< 0.1 (95% C.L.)
pp
• Measured (2S) double ratio
vs. centrality
– no strong centrality dependence
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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(1S) Nuclear Modification Factor: RAA
• CMS PbPb at 2.76 TeV
• In 2010: 7.28 µb−1
– (1S) RAA, 3 centrality bins
– JHEP 1205 (2012) 063
• In 2011: 150 µb−1
– (1S) RAA, 7 centrality bins
– First results on (2S) RAA
• Clear suppression of (2S)
– (1S) suppression
• Consistent with excited state
suppression only
• ~50% feed down
CMS Preliminary,
arXiv:1208.2826
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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Comparison: RHIC and LHC
• STAR measured RAA of
(1S+2S+3S) combined
– arXiv:1109.3891
– min. bias value:
• CMS: separate RAA for
(1S) and (2S)
– can calculate min. bias RAA
of (1S+2S+3S):
CMS Preliminary,
arXiv:1208.2826
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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ϒ RAA Comparison to models I
• Incorporating lattice-based
potentials, including real and
imaginary parts
– A: Free energy
• Consistent with data vs. Npart
• Includes sequential melting and
feed-down contributions
– ~50% feed-down from cb.
• Dynamical expansion, variations in
initial conditions (T0, η/S)
– Data indicate:
• 428 < T0 < 442 MeV at RHIC
• 552 < T0 < 580 MeV at LHC
• for 3 > 4pη/S > 1
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
•
– B: Internal energy
M. Strickland, PRL 107, 132301 (2011).
• Disfavored, not shown.
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ϒ RAA Comparison to models II
Strong
Weak
Binding
• Weak vs. Strong Binding
– Narrower spectral functions for “Strong”
case
– Ratios of correlators compared to Lattice:
favor “Strong” binding case
• Kinetic Theory Model
– Rate Equation: dissociation + regeneration
– Fireball model: T evolution. T ~ 300 MeV
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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ϒ RAA Comparison to models II
Eur. Phys. J. A (2012) 48: 72
• Comparison to data for “Strong” binding:
– Mostly consistent with data
– Little regeneration: Final result ~ Primordial suppression
– Large uncertainty in nuclear absorption. Need dAu, pPb.
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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ϒ RAA pT and y dependence
1.4
1.2
1
0.8
0.6
0.4
0.2
¡ (1S)
4p h/S = 2
4p h/S = 3
M. Strickland
4p h/S = 1
CMS PbPb sNN = 2.76 TeV
T
Cent. 0-100%
0 < p < 20 GeV/c
6
8
|y|
10
12
14
16
18
Cent. 0-100%
|y| < 2.4
CMS PbPb sNN = 2.76 TeV
¡ (1S)
4
M. Strickland
4p h/S = 1
2
20
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
2.5
2
1.5
1
0.5
0
0
T
p (GeV/c)
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Manuel Calderón de la Barca Sánchez
9/18/12 HIT Seminar, Berkeley Lab
RAA
RAA
• Indications that suppression is largest at low pT.
and mid rapidity.
– Need more statistics for firmer conclusions.
The
line...
• STAR and CMS:
– suppression vs. Npart.
– RAA consistent with suppression of
feed down from excited states only
(~50%)
• CMS: First measurement of
(2S) suppression
– RAA((3S)) < 0.09 (95% C.L.)
• (1S) RAA consistent with
suppression of feed down from
excited states only (~50%)
– Need more pp statistics to pin down
lower-pT double ratio
– Pinning down the medium
properties.
• Cold nuclear matter:
– coming soon!
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez
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