Recent results from ALICE - RHIG - Wayne State University

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Recent results from ALICE - RHIG - Wayne State University

ALICE Results at the LHCJohn Harris (Yale) for ALICE Collaboration 1 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


LHCAliceDedicated “general purpose”Heavy Ion experiment at LHCJohn Harris (Yale) for ALICE Collaboration 2 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Why Heavy Ions at the LHC?• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ sets stage for particle production / dynamics• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling? Interaction times?– Does the system still equilibrate rapidly?Thermal model still apply? → T still ~ T c (lattice QCD)?– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?– Is the QGP still strongly- (or weakly-) coupled?Liquid? More like a gas? Impact on energy loss! → “Nearly-perfect” fluid flow? viscosity?• Understand parton energy loss! – What are the microscopic processes?Mass and flavor dependence? → use high p T jets & tag heavy quark jets• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet• Color screening of the medium! – Is the system deconfined (vs LQCD), initial T?→ J/ψ & Y statesJohn Harris (Yale) for ALICE Collaboration 3 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity in PbPb*→ Centrality Dependence of Particle Multiplicity in PbPb*• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling? Interaction times?→ Bose-Einstein (3D HBT) Correlations in PbPb*– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow in PbPb*• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb*• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?→ Quarkonium Yields in PbPb* publishedin progressJohn Harris (Yale) for ALICE Collaboration 4 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Collaboration~ 1000 Members(63% - CERN States)~ 30 Countries~ 100 InstitutesUS ALICE – 13 Institutions57 members (inc. 12+ grad. students)Cal. St. U. – San Luis Obispo, Chicago St. University,Creighton University, University of Houston,Lawrence Berkeley Nat. Lab, Lawrence LivermoreNat. Lab, Oak Ridge Nat. Lab, Ohio State University,Purdue University, University of Tennessee,University of Texas at Austin, Wayne State University,Yale UniversityIndiaArmeniaUkraineMexicoJINRRussiaRomania Spain/CubaJapanSouth AfricaUSAChinaCroatiaNetherlandsHungaryUKGreeceSwedenPolandNorwaySlovak Rep.Czech Rep.BrazilKoreaCERNDenmarkItalyFranceGermanyFinlandJohn Harris (Yale) for ALICE Collaboration 5 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


The ALICE Experiment• Fully Installed & Commissioned – Hadron & µ CapabilitiesITS, TPC, TOF, HMPID, MUONS, V0, T0, ZDC, ACORDE, TRIGGER, HLT• EM (e and γ ) Partial Capabilities - (2010, 2011 in % below)TRD (40, 60%), PHOS (60, 60%) & EMCAL (40, 100 %) completeJohn Harris (Yale) for ALICE Collaboration 6 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Data-Taking at the LHCYEAR BEAM ENERGY EVENTS (TRIG) STATUS√s NN2009 pp 0.9 TeV 3 x 10 5 (MB) analysis complete2009 pp 2.36 TeV ~ 4 x 10 4 (MB) ITS, dN ch /dη only2010 pp 0.9 TeV ~ 8 x 10 6 (MB) partially analyzed2010 pp 7.0 TeV ~ 8 x 10 8 (MB) partially analyzed~ 5 x 10 7 (muons)~ 2 x 10 7 (high N ch )2010 Pb-Pb 2.76 TeV few x 10 7 in progressLHC - increased pp luminosity (L) by 10 5 in 2010 (to L pp > 2x10 32 )- delivered > 8 µb -1 Pb in 4 weeks (to L PbPb > 2x10 25 , ~ 1/20 L max - PbPb )John Harris (Yale) for ALICE Collaboration 7 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE pp Physics ApproachHeavy Ion Comparison Data- e.g. yields & spectra in Pb-Pb vs “scaled” ppMinimum Bias Events at LHC energies- compare to lower energies- tune Monte Carlos for SM backgroundSoft & semi-hard QCD- complementary to other LHC experiments- address issues of QCDVery high multiplicity pp events- dN ch /dη comparable to RHIC Cu-Cu data → QGP?John Harris (Yale) for ALICE Collaboration 8 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE pp Physics Results SummaryGlobal Event PropertiesN ch multiplicities & distributions 0.9 TeV: EPJC: Vol. 65 (2010) 1110.9 TeV/2.36 TeV: EPJC: Vol. 68 (2010) 897 TeV: EPJC: Vol. 68 (2010) 345pbar/p ratio (0.9 & 7 TeV) PRL: Vol. 105 (2010) 072002Momentum distributions (0.9 TeV) PLB: Vol. 693 (2010) 53QCD issuesBose-Einstein (HBT) correlations 0.9 TeV: PRD: Vol. 82 (2010) 0520010.9 & 7.0 TeV: arXiv:1101.3665In ProgressIdentified particles (π,K,p) 7 TeV HBT Strangeness (K 0 ,Λ,Ξ,Ω,φ)event properties: spectra, PID’d particles, high mult.Heavy flavor: charm (D 0 ,D + , D*) heavy quarks (c,b) -> µ, e J/y -> µ + µ - , e + e -pQCD: Event topology, underlying event, jet fragmentation, …HI Comparison Data (discussed in this talk)John Harris (Yale) for ALICE Collaboration 9 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Soft Physics in ALICE at the LHCLHC Heavy Ions in general –• Expectations are based on pQCD predictions and RHIC results• A lesson from RHIC – guided by theory + versatility + “expect the unexpected”Soft Physics (p T ≤ 2 GeV/c) with heavy ions at LHC –• Smooth extrapolation from SPS → RHIC → LHC?Event Characterization (baseline, shadowing, CGC, …. )• Multiplicity, centrality, transverse momentum and pseudo-rapidity distributions→ ALICE to measure comprehensive set of soft observables→ Couple with RHIC results to understand URHI collision dynamics (timescales)John Harris (Yale) for ALICE Collaboration 10 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity in PbPb→ Centrality Dependence of Particle Multiplicity in PbPb• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling? Interaction times?→ Bose-Einstein (3D HBT) Correlations in PbPb– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow in PbPb• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?→ Quarkonium Yields in PbPb* publishedJohn Harris (Yale) for ALICE Collaboration 11 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Charged Particle MultiplicityALICE, Phys. Rev. Lett. 105, 252301 (2010)√s NN = 2.76 TeV Pb + Pb central (0-5%)Pb-Pb (√sNN = 2.76 TeV)→ 1.9 x pp(√sNN = 2.36 TeV)→ nuclear amplification!dNch /dη /0.5 〈N part 〉 = 8.3 ± 0.4 (sys.)→ 2.2 x central Au-Au(√sNN = 0.2 TeV)John Harris (Yale) for ALICE Collaboration 12 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


dNch /dη – Comparisons to TheoryALICE, Phys. Rev. Lett. 105, 252301 (2010)√s NN = 2.76 TeV Pb + Pb central (0-5%)dNch /dη = 1584 ± 4 (stat.) ± 76 (sys.)pQCD Monte CarloShadowing / Saturationpp extrapolationEε (τ) = =V1τ 0 AdNdη 〈m T〉(η,y ∼ 0)∴ ε (τ) LHC ≥ 3 ε (τ) RHICJohn Harris (Yale) for ALICE Collaboration 13 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


dNch /dη – Centrality DependenceALICE, Phys. Rev. Lett. 106, 032301 (2011)LHC ~ RHIC !(interpolation 2.36 ↔ 7.0 TeV)John Harris (Yale) for ALICE Collaboration 14 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


dNch /dη – Centrality Dependence vs TheoryALICE, Phys. Rev. Lett. 106, 032301 (2011)dNch /dη /0.5 〈N part 〉 vs centrality (~ 〈N part 〉 )Soft processes dN ch /dη ~ N scattered nucleons (participants) ~ N part∴ “nuclear amplification” → independent of √sHard processes dN ch /d η ~ N nucleon-nucleon collisions∴ increased importance with √s & centralityPredictions• DPMJET MCright 〈dNch/dη〉 – wrong reason• HIJING MC• OthersStrong centrality dependenceGluon shadowingSaturation models:Color Glass Condensate,“geometrical scaling”• Post-dictions / Fine-tuning!DPMJETSaturation ModelsHIJINGImportant constraint for models &sensitive to details of initial state,saturation, evolution….!John Harris (Yale) for ALICE Collaboration 15 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity in PbPb→ Centrality Dependence of Particle Multiplicity in PbPb• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling?Interaction times?→ Bose-Einstein (3D HBT) Correlations in PbPb– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow in PbPb• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?* published→ Quarkonium Yields in PbPbJohn Harris (Yale) for ALICE Collaboration 16 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Space-time Evolution of System – Freezeout VolumeALICE, arXiv:1012.4035v2 [nucl-ex] 2011Bose-Einstein Correlations → R out R side R long → V (homogeneity region)V LHC ~ 2 x V RHIC !R out R side R long → V (homogeneity region) linear dependence on dN ch /dηV (central PbPb) at LHC ~ 300 fm 3John Harris (Yale) for ALICE Collaboration 17 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Space-time Evolution of System – Decoupling TimeALICE, arXiv:1012.4035v2 [nucl-ex] 2011Bose-Einstein Correlations → Decoupling time τ f → τ f ~ R longτ f (LHC) ~ 1.4 x τ f (RHIC) !τ f ~ 〈dN ch /dη〉 1/3τ f (central PbPb) ~ 10 – 11 fm/cJohn Harris (Yale) for ALICE Collaboration 18 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity→ Centrality Dependence of Particle Multiplicity• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– Does system still equilibrate rapidly? Is the QGP still strongly- (or weakly-) coupled?Thermal model still apply?→ T still ~ T c (lattice QCD)?– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?→ J/ψ & Y states* published→ Quarkonium Yields in PbPbJohn Harris (Yale) for ALICE Collaboration 19 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


yzElliptic Flow SaturatesHydrodynamic Limit• Azimuthal asymmetry of chargedparticles:dn/dφ ~ 1 + 2 v 2 (p T ) cos (2 φ) + ...xMass dependence of v 2Requires -• Early thermalization(0.6 fm/c)curves = hydrodynamic flowzero viscosity, Tc = 165 MeV• Ideal hydrodynamics(zero viscosity)Quark-Gluon EoS→ “nearly perfect fluid”John Harris (Yale) for ALICE Collaboration 20 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


v 2 Predictions for the LHCHeinz, Kolb,SollfrankHirano, to check reference….N.Borghini andU.A.Weidemann, J.Phy.G35 (2008) 023001Hirano et al ,nuclth/0701075v2John Harris (Yale) for ALICE Collaboration 21 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Elliptic Flow from ALICE at the LHCALICE, Phys. Rev. Lett .105, 252302 (2010)Very little change in v 2 vs p t between 0.2 TeV (STAR) and 2.76 TeV (ALICE)For three different centrality classes → consistent with hydro (Heinz; Eskola)!John Harris (Yale) for ALICE Collaboration 22 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Elliptic Flow at RHIC and LHCL. Kumar (STAR), IPAQGP 2010STAR: PRC 77 (2008) 054901; PRC 75 (2007) 054906ALICE, Phys. Rev. Lett .105, 252302 (2010)v 2 {4}v2 vs pTsame for 2.76 TeV down to 0.039 TeV!v 2 {EP}p T (GeV/c)Change in v2 vs pTbelow 39 GeV (at 7.7 & 11.5 GeV)!p T (GeV/c)John Harris (Yale) for ALICE Collaboration 23 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Integrated Elliptic Flow from ALICEALICE, Phys. Rev. Lett .105, 252302 (2010)30%Integrating v 2 over p T : 30% increase from 0.2 TeV (STAR) to 2.76 TeV (ALICE))Over all centrality classes!John Harris (Yale) for ALICE Collaboration 24 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Elliptic FlowALICE, Phys. Rev. Lett .105,252302 (2010)• Increase in v 2 from RHIC toLHC.• Larger than ideal hydro.• Viscous corrections needed!• Range of model calc’s sincefit v 2 at LHCwith various approachesV 2 versus √s NN (GeV)20 – 30 %centrality• Larger integrated elliptic flow at LHC due to increase in the mean p T .• Future:Elliptic flow with identified particles to p T ~ 10 GeV/c→ to get role of expansion in development of elliptic flow.John Harris (Yale) for ALICE Collaboration 25 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


RAA at the LHCALICE, Phys. Lett. B 696 (2011) 30.Charged particlesCentral Pb-Pb suppressed!Peripheral Pb-Pb less!John Harris (Yale) for ALICE Collaboration 28 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


RAA at LHC Relative to RHICALICE, Phys. Lett. B 696 (2011) 30.Charged particlesRAA minimum:LHC ~ 0.5 RHICLHC RAA:rise with pT above 7 GeV/cNext:• Increase statistics and pT• Will take pp reference at 2.76 TeV!• PID: Baryons, mesons, heavy flavor!RHIC suppression < LHCRHIC: high pT hadrons hadronize from quarks LHC: from gluons (larger color charge!)John Harris (Yale) for ALICE Collaboration 29 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Rise in RAA at LHC Relative to RHICALICE, Phys. Lett. B 696 (2011) 30.Kopeliovic et al arXiv:1012.2854v1Color transparency – rise at high pT~ survival of color dipole in mediumCharged particlesRHIC suppression < LHCRHIC: high pT hadrons hadronize from quarks LHC: from gluons (larger color charge!)John Harris (Yale) for ALICE Collaboration 30 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


“Mature” Prediction for RAA at LHC and RHICPrediction:I. Vitev (hep-ph/050322v1)• GLV – pQCD factorization• medium-induced gluon brems.But:This and previous model arediametrically opposite!More work to understand!John Harris (Yale) for ALICE Collaboration 31 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity in PbPb→ Centrality Dependence of Particle Multiplicity in PbPb• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling?Interaction times?→ Bose-Einstein (3D HBT) Correlations in PbPb– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow in PbPb• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?→ Quarkonium Yields in PbPbin progressJohn Harris (Yale) for ALICE Collaboration 32 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


High pT Correlations in Pb-PbSee talks by Andrew Adare &Anthony Timmons!High pT Jets in Pb-Pb0-10% central10-20% peripheral102 GeV47 GeV168 GeVbin size: 0.1x0.1192 GeV∆φ∆η∆φ∆ηThese are charged jets!ALICE EMCal just installed for 2011 run!John Harris (Yale) for ALICE Collaboration 33 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


ALICE Heavy Ion Results at the LHC• Determine Initial Conditions – What is the extent of shadowing, saturation, CGC?→ Particle Multiplicity in PbPb→ Centrality Dependence of Particle Multiplicity in PbPb• Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC!– What are the reaction dynamics? Transport properties?Space-time evolution of system? → System size at decoupling?Interaction times?→ Bose-Einstein (3D HBT) Correlations in PbPb– Does it flow?Elliptic Flow change?→ v 2 still saturated? More or less v 2 ? p T dependence?→ Elliptic Flow in PbPb• Understand parton energy loss! – What are the microscopic processes?→ R AA in PbPb• Understand response of the medium! – Strongly interacting quarks and gluons?→ away-side response, punch-thru, associated jet→ Particle Correlations in PbPb• Color screening of the medium! – Is system deconfined (vs LQCD), what is initial T, other effects?→ Quarkonium Yields in PbPbin progressJohn Harris (Yale) for ALICE Collaboration 34 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Quarkonium Suppression (future)LHC relative to RHIC:• Expect stronger suppression of J/ψ,Υ’,Υ’’• Υ suppression will depend on T-or-J/ Υ enhancement, Υ’, Υ’’ suppression dueto recombination of charm to J/ψ maskingsuppression.See talk of A. Grelli at this workshopPb-Pb Min. Bias data:• expect few 1000 J/Ψ from 2010 data• 5 – 10 (?) x more in 2011• Υ family needs integral L ~ 1-2 nb -1John Harris (Yale) for ALICE Collaboration 35 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011


Summary and Conclusions• ALICE up, running, producing physics (pp, Pb-Pb) → more to come from 2010• Charge multiplicities increased over RHIC → energy densities ε LHC ≥ 3 ε RHIC• Charge multiplicities ~ favor pQCD models, saturation models tend to be low• Centrality dependence of dN ch /dη constrains models (shape LHC ~ RHIC)• Freeze-out volume: V ~ 300 fm 3 ~ 2 x RHIC• Decoupling time: τ f (central PbPb) ~ 10 – 11 fm/c ~ 1.4 RHIC• v 2 vs p t ~ same for RHIC and LHC for all centrality classes studied• Integrated v 2 (over p t ) ~ 30% increase over RHIC for all centrality classes→ increase larger than ideal hydro→ increased role of viscous corrections at LHC• RAA (central collisions) suppressed at large pTsuppressed more than at RHIC, rises at larger pT• More to come from ALICE from 2010 data2011 → 2.76 TeV pp reference, increased L, PID, full jets, ….John Harris (Yale) for ALICE Collaboration 36 Winter Workshop, Winter Park CO, 6 – 12 Feb 2011

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