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Quarkonia with the first LHC data in ALICE. Mercedes Ló pez Noriega IPNO 25/09/2009. Heavy quarks at the LHC. Heavy quarks (c and b) will be abundantly produced in heavy ion collisions. Produced in the initial parton collisions, they can be used to probe deconfinement - PowerPoint PPT Presentation
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Quarkonia with the first LHC data in ALICE
Mercedes López NoriegaIPNO
25/09/2009
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 2
Heavy quarks at the LHC• Heavy quarks (c and b) will be
abundantly produced in heavy ion collisions.
• Produced in the initial parton collisions, they can be used to probe deconfinement
• Upsilon (bb) will be produced in an amount of the order of J/ at RHIC
• Some effects might become important:•heavy quarks energy loss in QGP•contributions from secondary quarkonia
SPSPbPbCent
RHICAuAuCent
LHCpp
LHCpPb
LHCPbPb Cent
cc 0.2 10 0.2 1 115
bb - 0.05 0.007 0.03 5
•|η| < 0.9 and -4 <η< -2.5
•Small xBj (10-3 –10-5)
ALICE
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 3
Why quarkonia?•Quarkonia: bound states of heavy quarks
–Charmonia (cc): J/, ’, c
–Bottomonia (bb): (1S), (2S), (3S)
•J/ production used as a probe of formed medium
–A deconfined medium J/ suppression due to color screening
(Matsui and Satz, Phys. Lett. B 178 (1986))
–Hard gluons needed for breaking J/ not available in hadron gas
(D. Kharzeev and H. Satz, Phys. Lett. B477 (2000))
–Calculations using lattice QCD: sequential suppression suppression of states is determined by T and their binding energy
• ’, c dissolves at T ~ TC
• J/ dissolves at T ~ 1.5 - 2 TC
(Satz, J.Phys.G32 (2006))
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 4
J/ at the LHC
•The suppression has been observed at SPS and RHIC, BUT!–Similar suppression at SPS and RHIC–Stronger suppression at forward than at mid-rapidity
•The results from PbPb collisions at 5.5 TeV will disentangle between the different suppression/regeneration scenarios
–Measuring either an excess on J/ production or a complete melting would imply deconfinement.
–An excess on the production would also indicate thermalization
•But we should take into account that:–bb cross-section will be large:
~ 20% of J/ originate from B decays (B+/- J/ + X+/-) –CNM effects will not be easy to quantify at the beginning (no pA run soon)
F.Karsch et al.: PLB637 75 (2006)
J/ regeneration?
J/ finally melts?
SPS RHIC LHC
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 5
ALICE
TRD
TPC
Central |η| < 0.9, in e+e-
• tracking: ITS, TPC, TRD• PID: TRD (e id.), TOF• secondary vertexing: ITS -4.0 < η< -2.5, in μ+μ-
Muon ArmITS
TOF
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 6
First pp run at the LHC
Present scenario (July 09)Present scenario (July 09)
900 GeV collisions
First high E collisions
Pilot run
Expected duration ~ shifts ~ weeks ~ months
N bunches @ ALICE 1 1 ( 2) 24 (100 ns spacing)
bunch intensity @ ALICE
5 1010 5 1010 1.5 1010
* m 10 10 3
transverse bunch size µm 280 84 46
luminosity cm-2 s-1 2.9 1027 3.2 1028 2.3 1029
MB rate s-1 150 2400 17 000
interaction rate per bc .01 .21 .06
pile-up probability .006 .11 .03
√spp = 7 TeV
Federico Antinori - Physics Forum - July Federico Antinori - Physics Forum - July 20092009
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 7
What ALICE will measure
assuming (just to get a feeling…):assuming (just to get a feeling…):– ““Pilot Run” conditions Pilot Run” conditions
(as in previous slide)(as in previous slide)– 1 kHz TPC rate1 kHz TPC rate– 300 k effective sec / month 300 k effective sec / month
(12% overall efficiency)(12% overall efficiency)
[serious uncertainties in all three…][serious uncertainties in all three…]
Federico Antinori - Physics Forum - July Federico Antinori - Physics Forum - July 20092009
What do we get for each 100 nbWhat do we get for each 100 nb-1-1??
e.g.: e.g.: 40 Hz single muon low p40 Hz single muon low pTT trigger rate trigger rate (based on ALICE-INT-2006-0002)(based on ALICE-INT-2006-0002)
– ~ 13 000 J/~ 13 000 J/ψψ (~150 with p (~150 with pTT > 11 GeV/c) > 11 GeV/c)
– ~ 250 ~ 250 ψψ‘‘– ~ 140 ~ 140 ΥΥ– ~ 35~ 35 Υ Υ‘‘ – ~ 20~ 20 Υ Υ‘‘‘‘
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 8
Quarkonia analysis in pp
Baseline for the analysis in PbPb collisions• J/ and Υ production yield and cross section
• J/ polarization• Upsilon family?• CGC
dielectron channel
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 9
Quarkonia via μ+μ- in pp
pp at 14 TeV, one year of data taking (integrated luminosity = 30 pb-1)
J/ψ Υ
Mass resolution (MeV/c2) ~70 ~100
Signal/Noise 12.0 10.4
pT range (GeV/c) 0-20 0-8
Counts2.8 106 2.7 104
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 10
Secondary J/ψ• χc: contribution ~30%
– χc J/ψ+γ• J/ψ in dielectron channel• γ in γ-convertion
– feasible in pp collisions but requires a trigger strategy which is under study
• B mesons: contribution ~20%– B J/ψ+X
• non-photonic electrons• “B tagging”: simultaneous fit
– Invariant mass distribution– Pseudo proper decay time
– In muon arm • method using 3 muon events is
under study
− tot J/ψ− J/ψ from B− bkg− sum
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 11
• Polarization– Angular distribution of μ+ in the
quarkonium rest frame.
•
•
–Upsilon polarization• 1 nominal year for integrated
studies• Several years for differentials
J/ψ polarization
ddcosH
1 cos2H
T 2 L
T 2 L
1 transverse
0 no polarization
1 longitudinal
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 12
Here in Orsay...
•J/ψ production yield and cross section in the dimuon channel
– dN/dpT:•yield with proper background estimation •study different fitting procedures
– Corrections •efficiency correction•acceptance correction
– Systematic errors•uncertainty on efficiency and acceptance corrections...
– Estimation J/ψ coming from B• method using 3 muon events is under study
•CGC (more in next slide...)
AccLdt
dpdN
dp
d T
T
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 13
J/Ψ RCP: looking for the CGC
x region probed by J/ψ production in p-p 14 TeV in the forward muon spectrometer
Event multiplicity groups:• B: small multiplicity [0-70]• M: medium multiplicity [70-95]• H: high multiplicity [95-150]
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 14
PbPb collisions at the LHC
Parameter Units Early Beam Nominal
Energy per nucleon TeV 2.76 2.76
Initial ion-ion Luminosity L0 cm-2 s-1 ~ 5 ×1025 1 ×1027
No. bunches, kb 62 592
Minimum bunch spacing ns 1350 99.8
* m 1.0 0.5 /0.55
Number of Pb ions/bunch 7 107 7 107
Transv. norm. RMS emittance m 1.5 1.5
Longitudinal emittance eV s/charge 2.5 2.5
Luminosity half-life (1,2,3 expts.)
h 14, 7.5, 5.5 8, 4.5, 3
J. Jowett, LHC Performance Workshop - Chamonix 2009
Only possibility for 2009-2010
Probably smaller!!
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 15
Analyses with the first PbPb collisions
•Quarkonia production yields and cross sections
•Quarkonia production suppression:• With respect to
– Beauty
– pp (RAA)
• As a function of– Centrality – Transverse momentum– Rapidity
•J/Ψ polarization
•v2 of J/ψ?
•Upsilon family?•CGC?
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 16
Quarkonia in PbPb collisions
J/ψ Υ
Mass resolution (MeV/c2)
~30 ~90
Signal/Noise 1.2 1.0
pT range (GeV/c) 0-10 0-10
Counts 120k 900
Dielectron channel(nominal PbPb year)
J/ψ Υ
Mass resolution (MeV/c2) ~70 ~100
Signal/Noise 0.3 2.5
pT range (GeV/c) 0-20 0-8
Counts (MB) 680k 6000
Dimuon channel
Mercedes López NoriegaRencontre ions lourds – Orsay 25/09/2009 17
We have plenty of work to do