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(di-)leptons & heavy flavors in heavy ion collisions at the LHC

(di-)leptons & heavy flavors in heavy ion collisions at the LHC. (di-)leptons & heavy flavors: what is different at the LHC The LHC heavy ion program Selected physics channels quarkonia open heavy flavors low mass dileptons some more exotic channels. Recent activities in the field.

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(di-)leptons & heavy flavors in heavy ion collisions at the LHC

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  1. (di-)leptons & heavy flavors in heavy ion collisions at the LHC • (di-)leptons & heavy flavors: what is different at the LHC • The LHC heavy ion program • Selected physics channels • quarkonia • open heavy flavors • low mass dileptons • some more exotic channels

  2. Recent activities in the field • ALICE col. J. Phys. G 30 (2004) 1517; • CMS col., CMS NOTE 2000-060; ATLAS col., CERN/LHCC/2004-009 • Hard probes in heavy ion collisions at the LHC • 4 working groups (PDF, shadowing and pA; Photons; Heavy quarks and quarkonia; Jet physics) • 3 workshops • 1 CERN Yellow Report: CERN-2004-009 (493 pages, 308 figures) • Heavy quarkonium working group • 6 working groups (Spectroscopy; Production; Quarkonium in media; Decays; Standard Model measurements; Future opportunities) • 3 workshops • 1 CERN Yellow Report: hep-ph/0412158 (521 pages, 260 figures) • HERA and the LHC • 5 working groups (Parton density functions; Multi-jet final states and energy flow; Heavy quarks (charm and beauty); Diffraction; MC tools) • 5 workshops • written document in preparation

  3. central AA hard gluon induced quarkonium breakup hep-ph/0311048 RHIC LHC Heavy flavors: what is different @ the LHC • large primary production • melting of (1S) by color screening • none of the primary J/ survives the (PbPb)QGP • large secondary production of charmonia • kinetic recombination, statistical hadronization, DD annihilation, b-hadron decay

  4. (di-)leptons: what is different @ the LHC dimuons in ALICE, pt > 2 GeV/c unlike-sign total unlike-sign from bottom unlike-sign from charm like-sign from bottom charm pure NLO S.Grigoryan • dileptons from b decay dominate the spectrum below  & J/ • large yield of secondary J/ from b decay • dileptons from b decay have different origin at low & high mass • sizeable yield of like-sign correlated dileptons from b decay

  5. Charm(onium) production, suppression, regeneration & in-medium modification time b decay • interplay between different processes @ different time scales • charm(onium) carries much more physics than anticipated DD annihilation hadronic comovers statistical hadronization kinetic recombination dropping mass, flow increased polarization momentum fluctuations color screening nuclear absorption quenching parton-(pre)resonance breakup pt broadening parton cascade systematic studies are a must hard scattering, shadowing

  6. How well is the heavy flavor production x-section known @ the LHC ? • theoretical uncertainties on absolute values: a factor 2-3 • theoretical uncertainties on the (5.5 TeV)/(14 TeV) ratio: few % •  measuring (ccbar, bbbar) in pp collisions @ 14 TeV is top priority N. Carrer and A. Dainese, hep-ph/0311225

  7. On the relevance of measuring (b) in pp collisions in the first days • (b) in pp is mandatory for understanding (b) in pA & AA (shadowing, quenching) • (b) in pp is mandatory for understanding () in pp, pA & AA (production, absorption, suppression) • (b) in pp is mandatory for understanding (J/) in pp (& pA, AA) (N(b  J/)/N(direct J/) ~ 30% in 4 w/o feed-down) • open heavy flavor statistics is much larger than quarkonium statistics •  (b) = day-one physics in pp collisions @ the LHC

  8. Heavy ion (ALICE) data taking scenario one LHC year = 7 months pp (107s) + few weeks AA (106s), starts in 2007 • 5 first years: • regular pp runs at 14 TeV: commissioning, reference, dedicated pp physics • first PbPb run at low luminosity: global observables, large x-sections • 2 PbPb runs at high luminosity (Lint = 0.5nb-1/year): small x-sections • 1 pA run: structure functions, hadronic reference • 1 light ion run: energy density dependence • later (different options depending on the first results): • pp (or pp-like) at 5.5 TeV • other light or intermediate-mass systems • other systems p-likeA • PbPb at low energy • PbPb at 5.5 TeV & high luminosity ALICE collaboration, J. Phys. G 30 (2004) 1517

  9. Heavy flavor physics program @ LHC(channels investigated so far) • charmonia & bottomonia versus • centrality • transverse momentum • system-size • reaction plane • open bottom (inclusive) • cross-section from 2nd J/, single leptons & dileptons • b quark energy loss • open charm (exclusive D’s) • transverse momentum distribution • c quark energy loss • electron-muon coincidences

  10. CMS: strong heavy ion program ATLAS: heavy ion LOI (2004) ALICE: the dedicated heavy ion experiment Heavy ions @ the LHC

  11. 1000 members 80 instituts 30 countries TOF DIPOLE MAGNET TRD HMPID L3 MAGNET PMD FMD ITS MUON TRIGGER CHAMBERS TPC PHOS MUON FILTER ABSORBER MUON TRACKING CHAMBERS ALICE (A Large Ion Collider Experiment)

  12. (di-)electrons: J/, ’, , ’,’’, open charm, open bottom electron-muon coincidences: open charm & bottom hadrons: exclusive D0 (di-)muons: J/, ’, , ’,’’, open charm, open bottom Heavy flavors with ALICE

  13. Heavy flavors with CMS muon spectrometer & silicon tracker in central barrel & end-caps large acceptance, excellent resolution J/, ’, , ’,’’, open charm, open bottom

  14. Heavy flavors with ATLAS muon spectrometer & silicon tracker in central barrel & end-caps large acceptance studies limited to  reconstruction & b-jet tagging so far

  15. Acceptance for heavy flavor measurements • nice complementarity between the 3 experiments • ATLAS & CMS acceptance is large in  & limited to high pt • ALICE combines hadrons, electrons, muons & covers low pt & high  • ATLAS, CMS & ALICE-electrons/hadrons have inner tracking

  16. barrel (||<1) Quarkonium measurements in ATLAS •  & ’ can be well separated • ’ & ’’ separation is difficult • J/ studies underway CERN/LHCC/2004-009, L. Rosselet@Vienna04

  17. Quarkonium measurements in CMS • M(dimuon) ~ 60 MeV @ M = 10 GeV in central barrel • background mainly coming from uncorrelated muon-pairs • J/ reconstruction limited to high pt G. Baur et al., CMS NOTE 2000-060

  18. background level 1 = 2 HIJING evts with dNch/d = 6000 @  = 0 each Quarkonium measurements in ALICE acceptance  mass resolution pt > 3 GeV/c trigger dielectrons pt > 3 GeV/c trigger pt > 2 GeV/c trigger dimuons pt > 1 GeV/c trigger • J/ measurement down to pt = 0 (unique @ the LHC) • resolution allows to separate the 3  states • note: no need for J/ trigger (at least in central PbPb collisions)

  19. Centrality dependence of quarkonium yields in ALICE-muon • cross-sections from R. Vogt in hep-ph/0311048, • assumes neither suppression nor enhancement • J/: large stat., good sign. • (allows much narrower centrality bins) • ’: small S/B • : good stat., S/B > 1, good sign. • ’: good stat., S/B > 1, good sign. • ’’: low statistics • similar rates for  in the dielectron channel S. Grigoryan (updated Dec.’04)

  20. ’/ ratio versus pt J.P. Blaizot & J.Y. Ollitrault, Phys. Lett. B 199(1987)499; F. Karsch & H. Satz, Z. Phys. C 51(1991)209; J.F. Gunion & R. Vogt, Nucl. Phys. B 492(1997)301 • Melting depends on • resonance formation time, dissociation temp. & pt • QGP temp., lifetime & size • Ratio is flat in pp (CDF) • Any deviation from the pp (pA) value is a clear evidence for the QGP (nuclear effects cancel-out) • The pt dependence of the ratio is sensitive to the characteristics of the QGP • full & realistic simulation • error bars = 1 month of central PbPb (10%) E. Dumonteil, PhD Thesis (2004) E. Dumonteil & P. Crochet, ALICE-INT-2005-002

  21. b-hadron cross-section from single muons & unlike-sign dimuons in PbPb UA1 MC method* used by CDF & D0, applied here# to central PbPb (5%) 1) get Nb from fits with fixed shapes (PYTHIA) & b yield as the only free parameter #R. Guernane et al., (2004) *C. Albajar et al., PLB 213 (1988) 405; PLB 256 (1991) 121

  22. b-hadron cross-section from single muons & unlike-sign dimuons in PbPb 2) for each  sample, correct Nb for eff. & Nevt, then convert to hadron cross-section total number of b from the fit integrated luminosity  global detection efficiency R. Guernane et al., (2004), C. Albajar et al., PLB 213 (1988) 405; PLB 256 (1991) 121

  23. “measured data points” input distribution b-hadron cross-section from single muons & unlike-sign dimuons in PbPb 3) the b-hadron inclusive differential cross-section distribution • input distribution well reconstructed • agreement between the 3 channels • statistics is (very) large • systematic uncertainties underway “a nice illustration that one can use Tevatron-like analyzes in PbPb collisions @ the LHC” R. Guernane et al., (2004)

  24. Bottom from single electrons with displaced vertices • d0 < d0cut: improve S/B for resonances • d0 > d0cut: measure electrons from D & B PbPb central (5%) B  e in ITS/TPC/TRD pt > 2 GeV/c, 200 < d0 < 600 m 40000 e from B, S/(S+B) = 90% CERN/LHCC 99-13, R. Turrisi, CERN HIF, 04/13/05

  25. A. Dainese, nucl-ex/0312005, nucl-ex/0405008 b-hadron inclusive differential cross-section from single electrons • same method as the one used with (di-)muons plus scenario for b-quark energy loss • electrons with 2 < pt < 16 GeV/c  b-hadrons with 2 < ptmin < 23 GeV/c • clear sensitivity to energy loss • will be further used to get RAAb-hadrons • RAAh, RAAD0 & RAAb-hadrons can be measured simultaneously R. Turrisi CERN HIF, 04/13/05 E-loss calculations: N. Amesto, A. Dainese, C.A. Salgado, U.A. Wiedemann, Phys. Rev. D 71 (2005) 054027

  26. From NA50’s (J/)/DY to ALICE’s /bbbar(assuming no quenching on b quarks) w/o  nuclear absorption with  nuclear absorption EPJC 39 (2005) 335 • statistics: one month PbPb • statistics of the reference is in 5<M<20GeV ~5 times larger than that of the probe • errors dominated by uncertainties on  nuclear absorption (~20%) • systematic errors underway R. Guernane & S. Grigoryan (2004)

  27. The Z0 as a normalisation to bottomonium suppression • most natural normalization to  is b (assuming quenching is under control!) • Z0: “clean” signal for normalisation (alternative to Drell-Yan which is out of reach) • not an universal normalisation (different shadowing for quarks & gluons) • Z0 in CMS: • b-hadron decays dominate the dimuon imass • 2 weeks PbPb @ L = 1027 cm-2s-1: 11000 Z0 +- in || < 2.5 CMS/NOTE 2001/008

  28. B  J/ (1S) anything: 1.16  0.10% (PDG) • N(direct J/) in central (5%) PbPb @ 5.5 TeV: 0.31 • N(bbbar pairs) in central (5%) PbPb @ 5.5 TeV: 4.56 •  N(b  J/) / N(direct J/) = 34% in 4 Secondary J/ from B decay • disentangle primary & secondary J/ • measure inclusive b cross-section • probe b quark in-medium energy loss ALICE: CERN/LHCC 99-13, CMS: CMS/NOTE 2001/008

  29. b-hadron cross-section from secondary J/in ppbar @ s = 1960 GeV (CDF results) D. Dacosta et al., Phys. Rev. D 71 (2005) 032001

  30. secondary J/ from B decay in CMS, pt > 5 GeV/c Using secondary J/ from B decayto probe b quark energy loss • energy loss is modeled in 2 extreme cases: • collisional energy loss (minimum) • collisional + radiative energy loss (maximum) • with energy loss: • yield reduced by a factor ~ 4 •  distribution gets significantly narrower interest to combine this study with dimuons from b-hadrons I.P. Lokhtin & A.M. Snigirev, Eur. Phys. J. C 21(2001)155

  31. ALICE dielectrons, central PbPb, pt > 1 GeV/c ALICE dimuons,proton-proton, pt > 0.5 GeV/c ALICE dimuons,central PbPb, pt > 1 GeV/c Low mass dilepton measurements • feasible in pp collisions (with ptl > 0.5 GeV/c & with Dalitz rejection in e+e-) • challenging in PbPb collisions (min ptl threshold = 1 GeV/c, trigger & bgd) • acceptance limited to high pt • excluded in ATLAS & CMS CERN/LHCC 99-13, B. Rapp, PhD thesis

  32. Some more exotic channels • Secondary J/ from tri-muon events in pp w/o 2nd vertex • b measurements from like-sign dileptons • electron-muon coincidences • Z measurements

  33. dimuon evts in pp, pt > 1GeV/c correlated muons correlated muons from b uncorrelated muons tri-muon evts in pp, pt > 1GeV/c S/B = 3 S/√S+B = 80 b-chain Secondary J/ from tri-muon eventsin pp w/o 2nd vertex reconstruction • dimuon events: • 85% of direct J/ • 15% of J/ from b decay • tri-muon events: • 15% of direct J/ • 85% of J/ from b decay doable in pp & pA, very difficult in central ArAr A. Morsch (2004)

  34. b measurements from like-sign dileptons 2 sources of like-sign correlated dileptons: • like-sign correlated b ~ unlike-sign correlated c • B0 oscillations ~ 30% of total like-sign correlated • clean signal (D mesons do not oscillate) • signal measurable via (like-sign)-(event-mixing) P. Crochet & P. Braun-Munzinger, Nucl. Instrum. Meth. A 484(2002)564

  35. Electron-muon coincidences • clean signal • covers intermediate rapidities • measurement done in pp @ ISR (1979!) • challenging in heavy ion collisions ALICE-INT-2000-01

  36. Z measurements with the ALICE muon spectrometer asymmetries in production & decay due to valence quarks PbPb PbPb PbPb acceptance • pp @ 14 TeV: accep ~ 14 %  71000  /run • PbPb @ 5.5TeV: accep ~ 10.8 %  13000  /run • background studies underway Z. Conesa del Valle, DIMUONnet’05

  37. (di-)leptons & heavy flavors in heavy ion collisions at the LHC • new environment, large statistics, new observables, new analyzes  rich physics program • further possibilities with dileptons • B+ J/ K+, B0  J/ K0s, B0s  J/ , b  J/  à la CDF & D0 • quarkonium & open heavy flavor flow • quarkonium polarization • dilepton correlations • first data in April 2007 ... stay tuned

  38. Recent results from CDF

  39. B measurements à la CDF A.Dainese, nucl-ex/0311004, 0312005

  40. Low mass resonances: acceptance    w/o pt cut pt 0.5 GeV/c pt 1 GeV/c

  41. ALICE PID

  42. xxx

  43. xxx

  44. B = 0.5 T Dpt/pt < 2% up to 10 GeV/c < 9% up to 100 GeV/c A.Dainese, SQM04 Tracking & Vertexing • D mesons ct ~ 100–300 mm, B mesons ct ~ 500 mm • Secondary vertex capabilities! Impact param. resolution! acceptance: pt > 0.2 GeV/c rf < 50 mm for pt > 1.5 GeV/c acceptance: pt > 1 GeV/c rf < 50 mm for pt > 2.5 GeV/c B = 4 T Dpt/pt < 2% up to 100 GeV/c

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