Quarkonia with the first LHC data in ALICE
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Transcript of Quarkonia with the first LHC data in ALICE
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