John Harris (Yale)Early Results and Future Prospects for the LHC Heavy-ion Program!LHC ALICE ATLAS CMS Large Hadron Collider John Harris (Yale) Jet Tomography vs Holography of the QGP, Columbia U, 20 Oct 2011LHC Heavy Ion Program LHC Heavy Ion Data-taking Design: Pb + Pb at √sNN = 5.5 TeV (1 month per year) Nov. 2010: Pb + Pb at √sNN = 2.76 TeV • LHC Collider Detectors - ATLAS - CMS - ALICEALICE Collaboration 1183 Members (2011) 118 Institutes 33 Countries SwedenPolandNorwayRussiaJINRJapanBrazilRomaniaSpain/CubaSouth AfricaUSAChinaCroatiaArmeniaIndiaKoreaUkraineMexicoCzech Rep.Slovak Rep.CERNDenmarkFinlandGermanyFranceIta lyGreeceUKHungaryNetherlandsUS ALICE 12 Institutions 89 members (inc. 22 students) Chicago St. U. Creighton U. U. of Houston Lawrence Berkeley Lawrence Livermore Oak Ridge Ohio State U. Purdue U. U. of Tennessee U. of Texas – Austin Wayne State U. Yale U.• EM (e and γ ) Capabilities - (% complete in 2011) TRD (60%), PHOS (60%), EMCAL* (100 %), DCAL* (install in 2013) * ALICE-USA The ALICE Experiment • Hadron & µ Capabilities - Fully Installed & Commissioned ITS, TPC, TOF, HMPID, MUONS, V0, T0, ZDC, ACORDE, TRIGGER, HLTGlobal ObservablesCharged Particle Multiplicity At mid-rapidity in central collisions Pb-Pb at √sNN = 2.76 TeV: → 1.9 x pp at √sNN = 2.36 TeV → nuclear amplification! → 2.2 x AuAu at √sNN = 200 GeV √sNN = 2.76 TeV Pb + Pb central (0-5%) ALICE, Phys. Rev. Lett. 105, 252301 (2010)dNch /dη – Comparisons to Theory dNch /dη = 1584 ± 4 (stat.) ± 76 (sys.) ALICE, Phys. Rev. Lett. 105, 252301 (2010) √sNN = 2.76 TeV Pb + Pb central (0-5%) pp extrapolation pQCD Monte Carlo Shadowing / Saturation ε (τ) = = E V 1 τ0A dN dη'〈mT〉 (η,y ∼ 0)'∴ ε (τ)LHC ≥ 3 ε (τ) RHICdNch /dη – Centrality Dependence ALICE, Phys. Rev. Lett. 106, 032301 (2011) LHC ~ RHIC ! (interpolation 2.36 ↔ 7.0TeV) dNch/dη centrality dependence – similar at LHC and RHICdNch /dη – Centrality Dependence vs Theory ALICE, Phys. Rev. Lett. 106, 032301 (2011) Two-component models: Soft processes dNch/dη ~ N scattered nucleons (participants) ~ Npart ∴ “nuclear amplification” → independent of √s Hard processes dNch/dη ~ N nucleon-nucleon collisions ∴ increased importance with √s & centrality • DPMJET MC Rises too strongly with Npart • HIJING MC (2.0), no quenching Centrality dependent – Gluon shadowing Tuned to 0-5% central Saturation-type models: Parametrization of saturation scale vs √s & centrality (A) geometric scaling DPMJET HIJING Important constraint for models & sensitive to details of initial state, saturation, evolution….! Saturation Models Predictions ALICE, C. Loizides, QM 2011 Data favor models with moderation of particle production vs centrality (also at RHIC)!RHIC Baryon Anomaly Re-appears at LHC! ALICE, J. Schukraft QM 2011 Enhanced baryon/meson ratio ala RHIC Increases with centrality Peak central B/m ratio x3 pp value Ratio at Maximum'x3 B/m ratio slightly larger at LHC than RHIC Little change with pT, although significant differences in spectraBigger Blast in dN /dpT for π, K, p at LHC! ALICE, J. Schukraft QM 2011 Slope changes at LHC vs RHIC Most dramatic for protons (in black) Blast Wave Fits'RHIC LHC Very strong radial flow, 'β ≈ 0.66 at LHC Stronger than predicted by recent hydroParticle Ratios Compared to Thermal Model B. Hippolyte, SQM 2011 Calculation by A. Andronic et al., Phys. Lett. B 673:142-145,2009 Work needed for understanding proton yields Grand canonical description for Kaons and multi-strange particles ?Central Collisions of Pb-Pb at the LHC produce dnch/dη per Npart pair ~ 2.2 RHIC and an energy density ≥ 3 x RHIC! Particle ratios (still few) same as at RHIC Baryon Anomaly still exists (similar) Stronger radial flow!Elliptic Flow – Energy Dependence ALICE, Phys. Rev. Lett .105, 252302 (2010) • Increase in v2 from RHIC to LHC. Described by hydrodynamics (various different calc’s) with: - Glauber geometry - viscous corrections η/s still small (~0.1-0.2) - changes expected in space-time evolution 20 – 30 % centrality V2 versus √sNN (GeV)Elliptic Flow – pT & Centrality Dependence ALICE, Phys. Rev. Lett .105, 252302 (2010) Very little change in v2 vs pt between 0.2 TeV (STAR) and 2.76 TeV (ALICE) For three different centrality classes → consistent with hydro (Heinz; Eskola)!Elliptic Flow – √sNN Dependence of v2(pT) v2 vs transverse momentum (pT) same for 2.76 TeV down to 39 GeV! ALICE, Phys. Rev. Lett .105, 252302 (2010) STAR: PRC 77 (2008) 054901; PRC 75 (2007) 054906 v2 {EP} pT (GeV/c) Change in v2 vs pT below 39 GeV (at 7.7 & 11.5 GeV)! pT (GeV/c) v2 {4} STAR preliminaryElliptic Flow at Large pT Characteristics: v2 inceases (up to ~ 3 GeV/c) v2 decreases (3 – 8 GeV/c) v2 ~ flat beyond Expected centrality dependence ALICE, A. Dobrin, QM 2011LHC Elliptic Flow – Identified Particles ALICE, M. Krzewicki, R. Snellings, QM 2011 arXiv:1105.3226v1 Hydro predicts incorrect mass-splitting at low pT Mostly due to proton flow, seen in spectra! Hydro fits v2 (π, K) , but NOT the most central p! CGC initial conditions, η/s = 0.2LHC & RHIC Elliptic Flow – Identified Particles ALICE, M. Krzewicki, R. Snellings, QM 2011 PHENIX bands: Phys. Rev. Lett. 91, 182301 (2003) STAR bands: Phys. Rev C 77, 054901 (2008) Larger mass splitting at LHC than at RHIC Hydro: CGC initial conditions, η/s = 0.2 ALICE (π, K, p) data points Hydro curves: Shen, Heinz, Huovinen & Song, arXiv:1105.3226Identified Particle Elliptic Flow at Large pT ALICE, A. Dobrin, QM 2011 Centrality dependence v2 (p) > v2 (π ) up to ~ 8 GeV/c PHENIX v2 (π0) ~ ALICE v2 (π±)Identified Particle Elliptic Flow – Quark Scaling? ALICE, M. Krzewicki, R. Snellings, QM 2011 Quark scaling appears to work for π and K at low pT Quark scaling does NOT work for protons at low pT Quark scaling may work (large errors) for π K p at high pTTwo-particle Correlations, Fluctuations See next talk by Andrew Adarev2 increases from RHIC to the LHC centrality & pT dependence of v2 same at LHC & RHIC (except decreases below √sNN = 39 GeV) larger v2 mass splitting (esp. protons) at LHC v2 (p) > v2 (π ) up to ~ 8 GeV/c v2 quark scaling does NOT work for protons at LHC described by viscous