31st Winter Workshop on Nuclear Dynamics
Keystone, CO
27/Jan/2015
 Heavy Quarkonium in
Heavy Ion Collisions

ϒ production

27/Jan/2015
pp, dAu, AuAu
collisions

Nuclear Modification

Comparison to models

Questions from trends
in data
From A. Mocsy
Manuel Calderón de la Barca Sánchez
2
 Heavy quarkonia are massive, produced
early

pQCD can estimate production
 Sensitive to temperature and deconfined
color fields: input from Lattice QCD

Debye screening, Landau damping


Re and Im V(r, T)
Different states have different sizes/binding
energies

Expect Sequential suppression
 Cold-nuclear matter effects


Initial state effects: e.g. nPDF
Final state: energy loss, absorption
Burnier, Kaczmarek, Rothkopf
arXiv:1410.2546
 Regeneration

Uncorrelated heavy quarks can pair up
 Bottomonium: a cleaner probe than
charmonium...



3 states are accessible experimentally
expect small CNM effects
expect small regeneration effects
27/Jan/2015
Manuel Calderón de la Barca Sánchez
3
 STAR: electron channel
 Analysis steps:



Triggering: L0, L2 (pp, dAu)
TPC tracking, e-ID via dE/dx
TPC-EMC match, e-ID via E/p
 Datasets




pp, 200 GeV (2009 Run)
d+Au 200 GeV (2008 Run)
Au+Au 200 GeV (2010 Run)
U+U 193 GeV (2012 Run, prel.)
 pp, d+Au, Au+Au Results:

27/Jan/2015
STAR: PLB 735 (2014) 127
Manuel Calderón de la Barca Sánchez
4
Counts
70
STAR p+p
s = 200 GeV
N+ ++N - - N+ -
Comb. Background (CB)
¡ (1S+2S+3S) ® l + l
120 STAR
p+p, s = 200 GeV
100
80
-
-1 -0.5
0
CEM: R. Vogt
CSM: Lansberg & Brodsky
STAR
PHENIX
1.5
2
2.5
y
¡
Manuel Calderón de la Barca Sánchez
NLO pQCD CEM
1
predictions.
Color Singlet Model
0.5
 Data ~ in between CEM and CSM
27/Jan/2015
60
40
-1.5
 Calculations:

20
Shape of Drell-Yan from NLO
pQCD (R. Vogt)
Shape of bb from PYTHIA.

60 |yee|<0.5
¡ (1S+2S+3S), Bl +l - ´ ds /dy (pb)
0
-2.5 -2

CB + Drell-Yan + bb
fit simultaneously, likelihood fit

50
 Unlike-sign and like-sign data are
CB + DY + bb + ¡ (1S+2S+3S)
Less inner material
12
13
mee (GeV/c2)

40

20 pb-1, all from pp run 2009.
Improvement over 2006 run:
11

30
STAR data:
10

STAR: PLB 735 (2014) 127
PHENIX: PRC 87, 044909 (2013)
9

8

20
10
0
 Results on cross sections
5
¡ (1S+2S+3S), Bl +l - ´ ds /dy (pb)
pp
STAR
pp
PHENIX
dAu / 1000
200
STAR
180
s
=
200
GeV
NN
¡ (1S+2S+3S) ® l + l
160
140
dAu / 1000
R. Vogt
pp
(a)
NLO pQCD CEM
dAu / 1000
compare RdAu, where many
theoretical and experimental
uncertainties cancel.
27/Jan/2015
120
¡
prediction,

1.5
2 2.5
y
 pp data also lower than
1

Calculation includes shadowing
Does not include estimate of
nuclear absorption
0.5

0
expectations from CEM.
100
-1 -0.5
 Midrapidity point is lower than
80
-1.5

Note: dAu scaled down by 103.
Int. Luminosity: 28.2 nb-1
60

40
comparison to pp.
20
0
-2.5 -2
 STAR dAu cross section and
Manuel Calderón de la Barca Sánchez
PLB 735 (2014) 127
6
Counts
35 STAR d+Au
N+ ++N - N+ -
Comb. Background (CB)
(b)
2
1.8
1.6
STAR RdAu (1S+2S+3S)
STAR p+p Syst. Uncertainty
PHENIX
Shadowing, EPS09 (Vogt)
0.5
Energy Loss (Arleo, Peigne)
Energy Loss + EPS09
0
1
1.5
2.5
y
¡
Manuel Calderón de la Barca Sánchez
(b)
2
27/Jan/2015
¡ (1S+2S+3S) RdAu
1.4
y~0 is right in the middle of the
antishadowing region
Expect RdAu > 1 (small effect)
Observe RdAu < 1
Absorption seems to be important
1.2
1
0.8
0.6
0.4
Arleo & Peigné
-1 -0.5

PLB 735 (2014) 127
-2 -1.5

sNN = 200 GeV
Energy loss
Energy loss + shadowing


R. Vogt
-2.5

CB + Drell-Yan + bb

CB + DY + bb + ¡(1S+2S+3S)
p+p´<Ncoll>
11
Shadowing, EPS09


12
13
mee (GeV/c2)
Model comparison:

30
|y |<0.5
ee
10
Scaled pp reference fit shown for
comparison
 RdAu vs. y

25
20
15
10
9

8
at |y|<0.5
5
0
 Invariant mass distribution in dAu
7
 Ratio of nuclear targets
normalized to deuterium
 Suppression seen with
increasing A.
a
s
=
A
s pp
 A dependence: pA
a1S = 0.962 ± 0.006
a 2S+3S = 0.948 ± 0.012
 STAR result is in the
same range:

PRL 66 (1991) 2285
for sdAu = (2 A)aspp :


a =ln(sdAu /spp )/ln (2A)
a ~ 0.9
 Suppression is the same for 1S and 2S+3S (within errors).

Drell-Yan is not suppressed, follows A scaling.
27/Jan/2015
Manuel Calderón de la Barca Sánchez
8
1.2
C
Ca Fe
W (a)
Au
1.3
a
1.2
1.1
E772 1S (pA), sNN = 40 GeV
E772 2S+3S (pA), sNN = 40 GeV
STAR 1S+2S+3S (dAu), sNN = 200 GeV
STAR 1S (dAu), sNN = 200 GeV
(b)
0.6
xF
0.7
Manuel Calderón de la Barca Sánchez
1
0.1 0.2 0.3 0.4 0.5
Note: dAu 2008 run was first attempt at
measuring bottomonium in cold nuclear matter,
can revisit with higher statistics
2015 plan for a p+A run at RHIC
27/Jan/2015
1.1
scaling
0
 A higher-statistics d+Au run would help.

1
0.96
-0.2 -0.1
 Effect goes away in the forward y bins.
0.9
0.7
explain suppression at y=0.

sdA/2
Aspp
,
A
PLB 735 (2014) 127
0.8
 Shadowing, or shadowing+E. Loss cannot
0.9
Same as STAR |y|<0.5 points.
0.8

0.7
a~0.9.
102
 Large suppression seen near xF~0 by E772,
Mass Number (A)
E772.
A(spd/2)
E772 1S (pA), sNN = 40 GeV, 0<y<1.05
 STAR result: consistent with A trend from
E772 2S+3S (pA), sNN = 40 GeV, 0<y<1.05
10

STAR 1S (dAu), sNN = 200 GeV, |y|<1.0

Increases the statistical uncertainty compared to
sum ϒ(1S+2S+3S)
Use|y|< 1, check A dependence.
Also compare y or xF dependence.
0.6

0.5
2
 For a similar comparison, separate ϒ(1S) state
spA
9
 Cold Nuclear Matter effects
are important!
 STAR dAu results show
suppression at y=0



Not expected from
shadowing
Absorption (or other effect)
seems to be needed
Similar effect seen in at
√s~40 by E772
27/Jan/2015
Manuel Calderón de la Barca Sánchez
10
sNN = 200 GeV, |yee|<1.0
140 STAR Au+Au
120
100
80
9.5
N+ ++N - N+ -
Comb. Background (CB)
CB + Drell-Yan + b b
(c)
CB + DY + bb + ¡ (1S+2S+3S)
p+p´<Ncoll>
10 10.5 11 11.5 12
 Scaled pp reference fit
shown for comparison
mee (GeV/c2)
 Yield extracted by
subtracting background
estimate from data.
60
9
 No L2 trigger on tower
pairs, only L0 single
high-tower trigger
0-10% centrality
8.5
 Au+Au 0-10% Most
central
40
20
0
8
 Integrated Luminosity:
1.08 nb-1.
Counts
PLB 735 (2014) 127
27/Jan/2015
Manuel Calderón de la Barca Sánchez
11
9
9.5
9.5
N+ ++N - -
N+ -
Comb. Background (CB)
CB + Drell-Yan + b b
(c)
CB + DY + bb + ¡ (1S+2S+3S)
p+p´<Ncoll>
10 10.5 11 11.5 12
(a)
mee (GeV/c2)
N+ -
10 10.5 11 11.5 12
p+p´<Ncoll>
CB + DY + bb + ¡ (1S+2S+3S)
CB + Drell-Yan + b b
Comb. Background (CB)
N+ ++N - -
10 10.5 11 11.5 12
p+p´<Ncoll>
CB + DY + bb + ¡ (1S+2S+3S)
(b)
mee (GeV/c2)
N+ ++N - -
N+ -
STAR Au+Au
9
9.5
CB + Drell-Yan + b b
Comb. Background (CB)
8.5
10-30% centrality
sNN = 200 GeV, |yee|<1.0
8.5
0-10% centrality
sNN = 200 GeV, |yee|<1.0
140 STAR Au+Au
120
100
80
60
40
20
0
8
140
120
100
80
60
40
20
0
8
sNN = 200 GeV, |yee|<1.0
60 STAR Au+Au
50
40
30
9
30-60% centrality
8.5
12
Manuel Calderón de la Barca Sánchez
27/Jan/2015
20
10
0
8
mee (GeV/c2)

Clear suppression of excited states.
Suppression of the ground state in the most central bin.

Counts
Counts
Counts
PLB 735 (2014) 127
 Invariant mass distributions in 3 centrality bins
 Possible to separate the ground state statistically.
 Comparison to Ncoll-scaled pp reference:
¡ (1S+2S+3S) R
AA,dA
2
1.8
1.6
1.4
1.2
1
STAR Au+Au
Strickland-Bazow Model
STAR Au+Au, Centrality Integrated
200
350
|y¡|<0.5
300
Emerick-Zhao-Rapp Model
250
400
400
Npart
(a)
(b)
350
|y¡|<1.0
300
Emerick-Zhao-Rapp Model
250
STAR d+Au
p+p Stat.+Fit Uncertainty
Common Normalization Syst.
150
STAR Au+Au, Centrality Integrated
100
STAR Au+Au
Strickland-Bazow Model
200
PLB 735 (2014) 127
dAu, and two most peripheral Au+Au bins: consistent with no suppression
Suppression in the most central Au+Au bin: Consistent with expectations for hot & cold nuclear matter,
however...
Right panel: bin closest to midrapidity, |y|<0.5


STAR ¡(1S+2S+3S)
sNN = 200 GeV
50
STAR d+Au
p+p Stat.+Fit Uncertainty
150
Common Normalization Syst.
100
STAR ¡(1S+2S+3S)
sNN = 200 GeV
50

0.8
0
2
0
Left panel: all data in STAR acceptance |y|<1


0.6
0
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Npart

0.4
AA,dA
0.2
¡ (1S+2S+3S) R
dAu suppression is of the same magnitude as central AuAu: Important to understand dAu system
Calculations:

Strickland & Bazow: Includes estimate of heavy quarkonium potential, Re and Im. Evolution through
anisotropic hydro. (Nucl. Phys. A 879 (2012) 25 ), T: 428 – 442 MeV (Depending on h/s, to match dN/dh)

Emerick, Zhao & Rapp: attempt to include both Hot & Cold nuclear effects. T0 = 330 MeV.
27/Jan/2015
Manuel Calderón de la Barca Sánchez
13
¡ (1S) R
AA,dA
2.5
2
1.5
1
0.5
0
0
STAR d+Au
STAR Au+Au
Liu-Chen Model
Strickland-Bazow Model
STAR Au+Au, Centrality Integrated
200
p+p Stat.+Fit Uncertainty
150
Common Normalization Syst.
100
STAR ¡(1S)
sNN = 200 GeV
50
250
350
|y¡|<1.0
300
(c)
400
Npart
PLB 735 (2014) 127
 Consistent with no suppression in dAu and peripheral AuAu
 Suppression in most central collisions


R AA(1S) = 0.66 ± 0.13(Au + Au stat.) ± 0.10(p + p stat.)+0.02 −0.05(Au + Au syst.) ± 0.08(p +
p syst.).
Models from Strickland et al., and Liu et al. consistent with central suppression

27/Jan/2015
However, neither model includes any CNM effects.
Manuel Calderón de la Barca Sánchez
14
 Measurements: vertical line


8
6
4
2
STAR dAu ¡ (1S+2S+3S)
No Suppression
a
A -scaling
1.2
(a)
(b)
1.4
 QGP+Aa scaling: consistent with
RAA
data
Probability Density
|y¡|<1.0
QGP Effects only
1
QGP effects + Aa scaling
STAR AuAu 0-10%
No Suppression
Based on Strickland et al.
 Aa scaling: consistent with dAu
AuAu data
PLB 735 (2014) 127
 Other scenarios are disfavored.
27/Jan/2015
12
10
8
A2a and QGP Effects
QGP effects only


A2a for AuAu
0.8

2a

A -scaling

No suppression: RAA=1
Aa scaling for dAu (CNM effect)
0.6

6
Run pseudoexperiments for
various scenarios
Stat. unc.: width of distributions
0.4

4

0.2
 Hypothesis test:
2
pink band: syst. unc.
0
0

Probability Density
10
RdAu
RAA, 0-10% most central
Manuel Calderón de la Barca Sánchez
15
 Hypothesis tests:
Probability Density
10
8
6
4
2
12
10
8
STAR dAu ¡ (1S+2S+3S)
No Suppression
a
A -scaling
|y¡|<0.5
QGP Effects only
STAR AuAu 0-10%
No Suppression
1
1.2
(c)
(d)
1.4
27/Jan/2015
RAA
Comparable to central AuAu
No particular scenario is
favored.

A2a and QGP Effects
2a
0.8
large suppression in dAu.

A -scaling
QGP effects + Aa scaling
 Clear that |y|<0.5 shows

6
0.6

Based on Strickland et al.
4
QGP effects only

2

A2a for AuAu
0.4

0.2

No suppression: RAA=1
Aa scaling for dAu (CNM
effect)
0
0

Probability Density
Additional statistics in dAu
would be beneficial.
Manuel Calderón de la Barca Sánchez
PLB 735 (2014) 127
16
RHIC √sNN=193 GeV U+U data
(2012)
 Reach higher Npart, Ncoll, Nch, than
in Au+Au
 Provide higherOpen
energy density
Charm

Production
Expect ~20% increase for U+U
– U+U –
compared to Au+Au
+
Oblate
U+U Collisions
+
e BUU/e BAuAu
Au+Au Collisions
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
+
27/Jan/2015
Prolate
0
0
Kikola, Odyniec, Vogt, PRC 84, 054907 (2011)
Masui, Mohanty, Xu, PLB 679, 440 (2009)
10
20
30
40
50
60
70
Centrality [%]
Manuel Calderón de la Barca Sánchez
17
comb. bg subtracted
e+e− pair invariant mass
U+U
√sNN=193 GeV
0-60%
STAR preliminary
STAR preliminary
 Similar method of yield extraction:


Likelihood fit.
Shape of D-Y from pQCD, bb
from PYTHIA.
27/Jan/2015
ϒ cross section (STAR preliminary)
U+U 193 GeV, 0-60% centrality
¡
ds AA
Bee
dy
= (4.37 ±1.09 +0.65 ) m b
|y|<1
Manuel Calderón de la Barca Sánchez
-1.01
stat.
syst
18
 Trend in U+U follows and extends that from Au+Au
27/Jan/2015
Manuel Calderón de la Barca Sánchez
19
RAA
0.4
0.8
¡(2S+3S), 95% limit
0-60% Centrality
0.6
J/y, p >5 GeV/c
T
0-10% Centrality
0.2
1.2 STAR Inclusive Quarkonium Measurements
Au+Au, sNN = 200 GeV, |y|<1
1
0.8
0.6
0.4
0.2
0
0
¡(1S)
0-10%
Centrality
1.4
1.2
1
Binding Energy (GeV)
 Overall pattern of sequential suppression in hot nuclear matter is observed.


Cold-nuclear matter effects: suppression in mid-rapidity d+Au larger than
predicted by shadowing/energy loss models.
p+Au data from 2015 will be useful to shed more light on this.
27/Jan/2015
Manuel Calderón de la Barca Sánchez
20
 p+p √s=500 GeV, 2011. L ~ 22 pb-1
 x-section larger than at 200 GeV
 L0-only
 excited-to-ground state ratio
27/Jan/2015
 pT spectrum, out to ~10 GeV/c
 Stat. error ~10%, up to ~25% at highest pT
 Efficiency/Acceptance corrections under
study.
Manuel Calderón de la Barca Sánchez
21
 Outermost, gas detector
 Physics goal: Precision
measurement of heavy
quarkonia through the
muon channel
 Acceptance:
45% in azimuth, |y|<0.5
RAA
1
0.8
0.6
0.4
ϒ projection
0.2
0
0
RAA
Complete in 2014, sampled ~13.8 nb-1 in Au+Au data
50
100
150
+
¡ (1S)®m m-
+
¡ (2S)®m m-
+
¡ (3S)®m m-
300
+ -
¡ (1S+2S+3S)®e e , |y|<0.5
250
350
NPart
Manuel Calderón de la Barca Sánchez
STAR Muon Telescope Detector
60 pb-1 p+p, 20 nb-1 Au+Au
200
27/Jan/2015
<Npart>
22
 ϒ: Measurements in STAR spanning pp,
dAu, A+A
 dAu data are now showing intriguing
features
1.2 STAR Inclusive Quarkonium Measurements
Au+Au, sNN = 200 GeV, |y|<1
1
0.8
¡(1S)
0-10%
Centrality
27/Jan/2015
¡(2S+3S), 95% limit
0-60% Centrality

1
1.2
1.4
Binding Energy (GeV)
Hint that suppression at y=0 in dAu is of
similar magnitude as central Au+Au:
0.8

0.6
very consistent with sequential
suppression picture.
J/y, p >5 GeV/c
T
0-10% Centrality
0.4
 AuAu data: Results from STAR look
0.6
0.4
0.2
0.2
Possible large suppression at y=0
0
0

RAA
Outlook: Higher statistics p+Au run will
be very helpful.
Manuel Calderón de la Barca Sánchez
23
27/Jan/2015
Manuel Calderón de la Barca Sánchez
24
27/Jan/2015
Manuel Calderón de la Barca Sánchez
25
 Model from Strickland et al.


Expect largest
suppression “dip” at y=0.
Changing model
parameters does not
change this feature.

Change in T profile




Change in shear viscosity
(and therefore initial T)


Gaussian profile
Boost invariant profile
Widens/narrows dip, but
dip remains
Increases/Decreases RAA
scale, but dip remains
Most (all?) models on the
market have this
behavior.

27/Jan/2015
Note: this model does not
have regeneration...
Manuel Calderón de la Barca Sánchez
26
 Antishadowing region is y~0 at RHIC, but y~-3 at LHC.
 LHCb: Slight enhancement at backward rapidity, indication of antishadowing
 ALICE: enhancement at backward rapidity, slight suppression.
 E. Loss+Shadowing (EPS09) consistent with LHCb backward y data, some tension with
ALICE


27/Jan/2015
EPS09 NLO: IJMP E22 (2013) 1330007
E. loss : JHEP 03 (2013) 122
Manuel Calderón de la Barca Sánchez
27
Strong
Weak
Binding
 Weak vs. Strong Binding



Binding energy changes (or not) with T.
Narrower spectral functions for “Strong” case
Ratios of correlators compared to Lattice: favor
“Strong” binding case
Emerick, Zhao & Rapp.
EPJ A (2012) 48:72
 Kinetic Theory Model


Rate Equation: dissociation + regeneration
Fireball model: T evolution.


27/Jan/2015
T ~ 300 MeV @ RHIC
T ~ 600 MeV @ LHC
Manuel Calderón de la Barca Sánchez
28
 Comparison to data:



Mostly consistent with
data
Little regeneration:
Final result ~
Primordial suppression
Large uncertainty in
nuclear absorption.
Need dAu, pPb.


27/Jan/2015
Based on our
preliminary result
RdAu=0.78
sabs ~ 1 – 3.1 mb
H
o
t
Emerick, Zhao & Rapp.
EPJ A (2012) 48:72
Suppression due to
nuclear matter:
can bring RAA down to ~0.6
(most central, lower edge of green band).
Additional suppression needed to bring
RAA down to ~0.4 :
nuclear effects
Manuel Calderón de la Barca Sánchez
29
 Study A dependence of ϒ family in pA.
 Fixed nuclear targets: liquid deuterium, C, Ca, Fe, W.
 proton beam @ 800 GeV.

Equivalent √s=√((800+1)2-(800)2)=√1601 ~ 40 GeV
 Measured Drell-Yan, ϒ(1S) and ϒ(2S+3S)

xF, x2 and pT dependence.
 Reminder about xF and rapidity:

Definition: xF = pZ/pZ(max) (in CM Frame), y=1/2 ln((E+pZ)/(E-pZ))
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For two protons at √s=40 GeV, pZ(max)=19.98 ~20 GeV
xF = 0 is equivalent to y = 0. (pZ=0 gives 0 for both)
For other values, need E, which means we need pT. Assuming pT~1 GeV:
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27/Jan/2015
xF = 0.1, pZ=2 GeV, E=10.247, y=0.198 ~ 0.2
xF = 0.2, pZ=4 GeV, E=10.817, y=0.388 ~ 0.4
xF = 0.3, pZ=6 GeV, E=11.704, y=0.566 ~ 0.6
Manuel Calderón de la Barca Sánchez
30
140
120
100
80
60
40
20
11
STAR Prelminary
Au+Au sNN = 200 GeV
|y ee|<0.5, Run 11
0-60% Centrality
N+ ++N- N+ Comb. Background (CB)
CB + Drell-Yan + bb
CB + DY + bb + ¡ (1S+2S+3S)
13
Integral of CB + DY + bb + ¡
12
31
Manuel Calderón de la Barca Sánchez
27/Jan/2015
10
 factor of ~3 in statistics.
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 same setup as in 2010
8
L ~ 2.8 nb-1
0
Au+Au √sNN=200 GeV,
2011