Heavy quarkonia perspectives with heavy-ions in ALICE E. Vercellin Università and INFN Torino – Italy For the ALICE collaboration

ALICE Set-up HMPID Muon Arm TRD PHOS PMD ITS TOF TPC Size: 16 x 26 meters Weight: 10,000 tons

Quarkonia detection in ALICE Performed both in the – dielectron channel (central barrel, key-detector: TRD) – dimuon channel ( forward rapidity region, Muon Spectrometer) Complementary features and performance

Quarkonia Acceptance – dimuon channel -J/  : p t,cut = 1 GeV/c Dimuon trigger: p t cut on individual muons to reject combinatorial background  : : p t,cut = 2 GeV/c

Quarkonia acceptance – dielectron channel Dielectron trigger: p t cut of 3 GeV/c on individual electrons. Not always needed (e.g. Pb-Pb central).

Running conditions at Point 2 Collision system√s NN (TeV)L 0 (cm -2 s -1 )Run time (s/year)  geom (b) pp * PbPb **7.7 pPb ArAr *L max = ** L int (ALICE) ~ 0.5 nb -1 /year + other ions (Sn, Kr, O) & energies (e.g.: 5.5 TeV)

Simulation inputs Quarkonia: –X-sect from Color Evaporation Model –Pt distribution extrapolated from CDF data –Feed-down from higher –resonances included –J/  from B decay included –Shadowing (EKS) Open heavy flavors –X-sect and kinematic distributions from NLO pQCD (NMR) –PYTHIA tuned to NLO for event generation –Shadowing (EKS)  /k : Hijing For more details see PPR Vol. II – J. Phys. G. Nucl. Part. Phys. 32 (2006)

Quarkonia to dielectrons: Pb-Pb Dielectron invariant mass spectrum in central collisions after one “ALICE-year” of Pb-Pb data taking

Quarkonia to dielectrons: Pb-Pb Dielectron invariant mass spectrum in top 10% central collisions after one “ALICE-year” of Pb- Pb data taking Zoom in the J/  region Zoom in the  region

Quarkonia to dielectrons: p-p

Quarkonia to dimuons: Pb-Pb Statistics for 0.5 nb -1 -J/  : excellent ( ) -  ’: marginal - Y: ok (7000) - Y’: low (2000) - Y’’: very low (1000) Normalization on open b B -> J/  + X

Quarkonia   +  - : suppression studies in Pb-Pb Statistical errors corresponding to one month run. Hp : “perfect” subtraction of comb. background Hp. Nucl. Absorpt. cross sect. = 0 (hint from RHIC) Shadowing + two QGP suppression scenarii: low vs. high diss. temperature Centrality dependence of J/  and  yields normalized to open beauty

Quarkonia   +  - : suppression studies in Pb-Pb Centrality dependence of  ’ / J/  and  ’/  ratios Same working hypothesis as previous slide J/ , Y, Y’: Excellent sensitivity to different suppression scenarios Y’’: Needs 2-3 years of high luminosity  ’:Will be very difficult

Quarkonia to dimuons: pp coll. at 14 TeV Statistics expected in a pp run of 10 7 s at L=310 30 cm -2 s 10 6 J/ 2.7 10 4  Invariant mass resolution at the J/  peak: ~ 70 MeV/c 2 Invariant mass resolution at the  peak: ~ 100 MeV/c 2

Quarkonia to dimuons in pp collisions at 14 TeV: study of p t and y distributions  p t distribution: test of prod. mechanisms (see Tevatron) J/ rapidity distribution: sensitivity to gluon distributions at low x ? (statistics for one pp run : 10 7 s at L=3  cm -2 s -1 )

Quarkonia polarization is reconstructed from the angular distribution of the decay products (J/   +  - ) in the quarkonia rest frame Measurement of quarkonia polarization in pp collisions y z x HH ++ p proj p targ J/  -- =+1 =-1 Transverse polarization Longitudinal polarization With the foreseen pp statistics the measurement of J/ polarization is feasible in ALICE, also as a function of p T

Conclusions Quarkonia production studied in Alice both in the dielectron and dimuon channels The two methods are complementary under different points of view. Quarkonia detected over a wide rapidity range from -4 till +0.9 Thanks to ALICE characteristics, quarkonia will be studied together with all known observables for heavy ion collisions Measurements in p-p collisions are a relevant part of the ALICE program