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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

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Quarkonia with the first LHC data in ALICE

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Quarkonia with the first lhc data in alice

Quarkonia with the first LHC data in ALICE

Mercedes López Noriega

IPNO

25/09/2009


Heavy quarks at the lhc

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

ALICE

  • |η| < 0.9 and -4 <η< -2.5

  • Small xBj (10-3 –10-5)

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


Why quarkonia

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 Tand their binding energy

      • ’, c dissolves at T ~ TC

      • J/ dissolves at T ~ 1.5 - 2 TC

        (Satz, J.Phys.G32 (2006))

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


J at the lhc

J/ at the LHC

SPS

RHIC

LHC

J/ regeneration?

F.Karsch et al.: PLB637 75 (2006)

J/ finally melts?

  • 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/y originate from B decays (B+/- J/ + X+/-)

    • CNM effects will not be easy to quantify at the beginning (no pA run soon)

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


Alice

ALICE

  • 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 Arm

ITS

TPC

TRD

TOF

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


First pp run at the lhc

First pp run at the LHC

Present scenario (July 09)

√spp = 7 TeV

Federico Antinori - Physics Forum - July 2009

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


What alice will measure

What ALICE will measure

assuming (just to get a feeling…):

  • “Pilot Run” conditions

    (as in previous slide)

  • 1 kHz TPC rate

  • 300 k effective sec / month

    (12% overall efficiency)

    [serious uncertainties in all three…]

What do we get for each 100 nb-1?

e.g.: 40 Hz single muon low pT trigger rate

(based on ALICE-INT-2006-0002)

  • ~ 13 000 J/ψ (~150 with pT > 11 GeV/c)

  • ~ 250 ψ‘

  • ~ 140 Υ

  • ~ 35 Υ‘

  • ~ 20 Υ‘‘

Federico Antinori - Physics Forum - July 2009

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


Quarkonia analysis in pp

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 Noriega

Rencontre ions lourds – Orsay 25/09/2009


Quarkonia via in pp

Quarkonia via μ+μ- in pp

pp at 14 TeV, one year of data taking (integrated luminosity = 30 pb-1)

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


Secondary j

Secondary J/ψ

  • tot J/ψ

  • J/ψ from B

  • bkg

  • sum

  • 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

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


J polarization

J/ψ polarization

  • Polarization

    • Angular distribution of μ+ in the quarkonium rest frame.

    • Upsilon polarization

      • 1 nominal year for integrated studies

      • Several years for differentials

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


Here in orsay

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...)

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009


J r cp looking for the cgc

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 Noriega

Rencontre ions lourds – Orsay 25/09/2009


Pbpb collisions at the lhc

PbPb collisions at the LHC

Probably smaller!!

Only possibility for 2009-2010

Mercedes López Noriega

Rencontre ions lourds – Orsay 25/09/2009

J. Jowett, LHC Performance Workshop - Chamonix 2009


Analyses with the first pbpb collisions

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 Noriega

    Rencontre ions lourds – Orsay 25/09/2009


    Quarkonia in pbpb collisions

    Quarkonia in PbPb collisions

    (nominal PbPb year)

    Dielectron channel

    Dimuon channel

    Mercedes López Noriega

    Rencontre ions lourds – Orsay 25/09/2009


    We have plenty of work to do

    We have plenty of work to do

    Mercedes López Noriega

    Rencontre ions lourds – Orsay 25/09/2009


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