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Upsilon Production in Heavy Ions with STAR and CMS. Manuel Calderón de la Barca Sánchez . HIT Seminar Berkeley Lab September 18, 2012. Outline. Bottomonium in heavy ion collisions Upsilon measurements in: STAR CMS Upsilon cross sections in p+p - PowerPoint PPT Presentation
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Upsilon Production inHeavy Ions with STAR
and CMS
Manuel Calderón de la Barca Sánchez
HIT SeminarBerkeley LabSeptember 18, 2012.
Manuel Calderón de la Barca Sánchez 2
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 3
Quarkonium in the QGP• Heavy quarkonia:
– Heavy quark bound state are probes of the hot QCD medium
– Debye screening • 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
TC<T0<T<TCT=0
ϒ
Manuel Calderón de la Barca Sánchez 4
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/ysuppression: • 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
O. Kaczmarek, et al.,Nucl.Phys.Proc.Suppl.129:560-562,2004
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 5
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 6
Measuring the Temperature
hep-ph/0110406
Dissociation temperatures of quarkonia statesLattice QCD Calculations: Quarkonia’s suppression
pattern QGP thermometer
• 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
• Expectation:– (1S) no melting– (2S) likely to melt– (3S) melts
A .Mocsy, 417th WE-Heraeus-Seminar,2008
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 7
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 8
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 9
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 Sánchez10
The CMS Detector
9/18/12 HIT Seminar, Berkeley Lab
• ϒ event in CMS.
Manuel Calderón de la Barca Sánchez 11
in p+p 200 GeV in STAR
9/18/12 HIT Seminar, Berkeley Lab
∫L dt = 7.9 ± 0.6 pb-1
N(total)= 67±22(stat.)
Phys. Rev. D
82 (2010) 12004
∫L dt = 19.7 pb-1
N(total)= 145±26(stat.)
2006 2009
STAR Preliminary
Manuel Calderón de la Barca Sánchez 12
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
CEM
: R. V
ogt,
Phys
. Rep
. 462
125,
200
8C
SM: J
.P. L
ansb
erg
and
S. B
rods
ky, P
RD
81,
051
502,
201
0
Manuel Calderón de la Barca Sánchez 13
• Excellent resolution at midrapidity.
• Separation of 3 states.
9/18/12 HIT Seminar, Berkeley Lab
in p+p 7 TeV in CMS
PRD 83, 112004 (2011)
Manuel Calderón de la Barca Sánchez 14
vs √s, World Data
9/18/12 HIT Seminar, Berkeley Lab
STAR √s=200 GeV and CMS √s=7 TeV p+p ++→e+e- cross section consistent with pQCD and world data trend
STAR Preliminary
Manuel Calderón de la Barca Sánchez 15
in d+Au 200 GeV
9/18/12 HIT Seminar, Berkeley Lab
∫L dt = 32.6 nb-1
N+DY+bb(total)= 172 ± 20(stat.)Signal has ~8σ significancepT reaches ~ 5 GeV/c
STAR Preliminary
Final results on RdAu coming soon. LHC pPb run in January/February.
Manuel Calderón de la Barca Sánchez 16
in Au+Au 200 GeV
9/18/12 HIT Seminar, Berkeley Lab
Raw yield of e+e- with |y|<0.5 = 197 ± 36
∫L dt ≈ 1400 µb-1
Manuel Calderón de la Barca Sánchez 17
in Au+Au 200 GeV, Centrality
9/18/12 HIT Seminar, Berkeley Lab
Peripheral Central
STAR Preliminary
STAR Preliminary
STAR Preliminary
Manuel Calderón de la Barca Sánchez 18
Bottomonia at 2.76 TeV: 2010 datapp PbPbPRL 107 (2011) 052302
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 19
Bottomonia: 2011 datapp PbPb
Ratios not corrected for acceptance and efficiency
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 20
in Au+Au 200 GeV, RAA
9/18/12 HIT Seminar, Berkeley Lab M
odel
s fro
m M
. Stri
ckla
nd a
nd D
. Baz
ow, a
rXiv
:111
2.27
61v4
•Indications of Suppression of Upsilon(1S+2S+3S) getting stronger with centrality.•Reduced pp statistical uncertainties, increased statistics from 2009 data vs 2006 data.
Manuel Calderón de la Barca Sánchez 21
(2S)/(1S) Double Ratio, CMS• Separated (2S) and (3S)
• Measured (2S) double ratio vs. centrality– no strong centrality dependence
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 22
(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
9/18/12 HIT Seminar, Berkeley Lab
CMS Preliminary,arXiv:1208.2826
Manuel Calderón de la Barca Sánchez 23
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):
9/18/12 HIT Seminar, Berkeley Lab
CMS Preliminary,arXiv:1208.2826
Manuel Calderón de la Barca Sánchez 24
ϒ RAA Comparison to models I• Incorporating lattice-based potentials,
including real and imaginary parts– A: Free energy
• Disfavored, not shown. – B: Internal 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 •M
. Stri
ckla
nd, P
RL
107,
132
301
(201
1).
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 25
ϒ RAA Comparison to models II
• 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
StrongBindingWeakBinding
Manuel Calderón de la Barca Sánchez 26
ϒ RAA Comparison to models II
• 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
Eur. Phys. J. A (2012) 48: 72
Manuel Calderón de la Barca Sánchez 27
ϒ RAA pT and y dependence
• Indications that suppression is largest at low pT. and mid rapidity. – Need more statistics for firmer conclusions.
9/18/12 HIT Seminar, Berkeley Lab
Manuel Calderón de la Barca Sánchez 28
The bottom 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