Prospects for First Measurements with ALICE in Pb+Pb Collisions at the LHC

LHC

Alice

Dedicated “general purpose” Heavy Ion experiment at LHC John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Heavy Ions at the LHC • Determine Initial Conditions – What is the extent of shadowing, saturation, CGC? → sets the stage for particle production / dynamics • Expect different timescales, shorter interaction times, higher energy (T) compared to RHIC! Does system still equilibrate rapidly?

Thermal model still apply? → T still ~ Tc (lattice QCD)? Does it flow?

Elliptic Flow change? → v2 still saturated? More or less v2? pT dependence? Is the QGP still strongly- (or weakly-) coupled? Liquid? More like a gas? → No longer “nearly-perfect” fluid flow? viscosity? → Impact on energy loss!! • Understand parton energy loss! – What are the microscopic processes? → mass and flavor dependence?

→ use high pT jets & tag heavy quark jets • Understand response of the medium! Strongly interacting quarks and gluons → away-side response? → use punch-through & associated jet • Color screening of the medium! Deconfinement? (compare LQCD), initial T, other effects → J/ψ & Y states

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE Collaboration

~ 1000 Members (63% - CERN States) ~ 30 Countries ~ 100 Institutes

Spain/Cuba Romania Japan Brazil South Africa Korea USA Italy China India Croatia Armenia Ukraine US ALICE – 13 Institutions Mexico 57 members (inc. 12+ grad. students) JINR Russia Cal. St. U. – San Luis Obispo, Chicago St. University, France Creighton University, University of Houston, Netherlands Lawrence Berkeley Nat. Lab, Lawrence Livermore Hungary Nat. Lab, Oak Ridge Nat. Lab, Ohio State University, UK Greece Germany Purdue University, University of Tennessee, Sweden Poland Finland University of Texas at Austin, Wayne State University, Norway CERN Slovak Rep. Denmark Yale University Czech Rep.

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 The ALICE Experiment

Fully Installed & Commissioned – Hadron & µ Capabilities

ITS, TPC, TOF, HMPID, MUONS, V0, T0, ZDC, ACORDE, TRIGGER, DAQ, HLT, DCS

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 The ALICE Experiment

EM (e and γ ) Partial Capabilities - (now, after next installation in % below)

TRD (40, 100%), PHOS (60, 80%) & EMCAL (40, 160 (inc. DCal) %) complete

JohnJohn Harris Harris (Yale) (Yale for ALICE U.) Collaboration US LHCINT Workshop, User’s Seattle,Meeting, Washington, 24 October May 25, 2008 2010 Soft Physics in ALICE at the LHC LHC Heavy Ions in general – • expectations based on pQCD predictions & RHIC results • a lesson from RHIC – guided by theory + versatility + “expect the unexpected”

Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • Smooth extrapolation from SPS → RHIC → LHC? • ALICE to measure comprehensive set of observables to determine dynamics

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE Detectors & Acceptance central barrel -0.9 < η < 0.9 • ∆φ = 2π tracking, PID (TPC/ITS/ToF) • single arm RICH (HMPID) • single arm e.m. cal (PHOS) (charged particles) • electron id (TRD) • EM calorimeter arms (EMCal + DCal) forward muon arm -4 < η < -2.4 • absorber, 3 T-m dipole magnet 10 tracking + 4 trigger chambers µ arm multiplicity detectors -5.4 < η < 3 • including photon counting in PMD trigger & timing detectors • 6 Zero Degree Calorimeters • T0: ring of quartz window PMT's • V0: ring of scint. Paddles

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Material Budget Cumulative mid-rapidity material budget for ALICE, ATLAS and CMS

ALICE x/X0 (%) ATLAS x/X0 (%) CMS x/X0 (%) Beam pipe 0.26 Beam pipe 0.45 Beam pipe 0.23 Pixels (7.6 cm) 2.73 Pixels (12 cm) 4.45 Pixels (10.2 cm) 7.23 ITS (50 cm) 7.43 SCT (52 cm) 14.45 TIB (50 cm) 22.23 TPC (2.6 m) 13 TRT (1.07 m) 32.45 TOB (1.1 m) 35.23

 Reconstruction and identification possible at low pT due to low material budgetB.Hippolyte Hot Quarks 2008 - Estes Park John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE Tracking Efficiencies, Momentum Resolutions Detector performance published in J. Phys.G32 (2006) 1295

Detector tracking efficiencies

Detector momentum resolutions

Central PbPb

Cosmic ray data

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Energy Loss (dE/dx) and PID in TPC

dE/dx as shown by Federico < 6 % resolution measured in p + p

separation power

Expect ~6.5% resolution in central Pb+Pb

to 50 GeV

5/25/2010 John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Identified Particle Spectra Particle reconstruction and identification capabilities: a strength of ALICE

Global tracking (ITS-TPC-TRD) & dE/dx (low pT + relativ. rise), TOF, HMPID, PHOS, EMCal Also invariant mass & topological reconstruction

Acceptance / efficiency / reconstruction (ε) / contamination 7 9 pT range (PID or stat. limits) for 10 central PbPb and 10 min. bias pp For ~ 20 particle species for -1 < y < +1 and -4 < y < +2.5 π, K, p: 0.1- 0.15 to 50 GeV Weakly/strongly decaying particles/resonances to 10-15 GeV

Mid-rapidity π PID in the K relativistic rise Pb-Pb p Pb-Pb

+ EMCal

pT (GeV/c) John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Centrality Determination in ALICE and 2010 Rates Event by event determination of centrality: Zero Degree Calorimeters (ZDC = ZP + ZN) + Z EM cal’s (ZEM)

E(ZDC) , E(ZEM) Nspec Npart Impact parameter (b)

LHC PbPb design: “Possibilities” for 2010 PbPb Run: 〈L〉 = 5 x 1026 cm-2s-1 〈L〉 ~ 1025 cm-2s-1, ~ 100 Hz, t ~106 s → ∫Ldt ~ 0.01 nb-1 → ~ 108 events

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE

Event Characterization (baseline, shadowing, CGC, …. ) • Multiplicity, centrality, transverse momentum and pseudo-rapidity distributions

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Initial Conditions at the LHC

N. Armesto, arXiv:0804.4158 LHC predictions: An overview

LHC (dn/dy)

(2600)

Establish initial conditions at LHC Particle Multiplicities (1200) →Measure particle multiplicities shadowing, gluon saturation, CGC? establish the topology for particle production and dynamics at LHC!

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE at the LHC Measure spectra & yields (vs centrality/multiplicity) with heavy ions

Transverse Momentum (pT) Distributions Tracking in TPC + ITS

〈 pT 〉 versus Multiplicity

Preliminary

in 0.3 to 4 GeV

versus multiplicity to tune Monte Carlo programs

TPC pt spectrum (and watch for surprises ?) Preliminary

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE

Event Characterization (baseline, shadowing, CGC, …. ) • Multiplicity, centrality, transverse momentum and pseudo-rapidity distributions

Bulk Properties of the Medium (T, µ, … ) • Particle ratios, hadronic resonances

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics – ALICE Performance Weak decay vertex reconstruction of strange particles

0 Λ → πp K s → ππ

PDG: 497.6 MeV PDG: 1115.7 MeV

7 pT reach (with 10 events): 13 -15 GeV/c (φ, K, Λ) 8 -12 GeV/c (ρ, Ξ, Ω) ∼ ∼

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE at the LHC Measure particle spectra and yields with heavy ions at LHC • identified mesons, baryons and resonances • including flavor production (strangeness, charm and beauty) • Chemical freezeout temperature ~175 MeV? If not, we are completely wrong

about interpretation of RHIC data! Twice initial T, still freezes out at Tcr? Had better!

• T, µB and volume are only parameters – connected to QCD phase boundary

B. Hippolyte et al. (ALICE) Eur. Phys. J. C49 (2007) 121.

Equ.

Non-Equ.

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE

Event Characterization (baseline, shadowing, CGC, …. ) • Multiplicity, centrality, transverse momentum and pseudo-rapidity distributions

Bulk Properties of the Medium (T, µ, … ) • Particle ratios, hadronic resonances

Chiral Symmetry Restoration? • Short-lived resonances & medium-modified masses

Collision Dynamics (space-time evolution, transport properties) • Momentum correlations (HBT) • Collective Flow (radial, anisotropic) • Baryon number transport

Fluctuations • Event-by-event – particles, momentum, …

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Resonances (ρ, φ, K*, …) → Hadrons Short-lived resonances: • Time difference between chemical and kinetic freeze-out • In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration?

• Reconstruct invariant mass spectrum, subtract background (like-sign method). • Mass resolutions ~ 1.5 - 3 MeV. pT statistical limits: 8 (ρ) to 15 GeV/c (φ,K*)

φ (1020) → K+K- ρ0(770) → π+π− 106 central Pb-Pb Mass resolution ~ 1.2 MeV

K*(892)0 K π 15000 central Pb-Pb

Invariant mass (GeV/c2) Invariant mass (GeV/c2) Mass resolution ~ 2-3 MeV

Invariant mass (GeV/c2)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Resonances (φ, ω, J/ψ) → e+e- •ShortIn medium-lived resonances: modifications of mass, width? • Compare hadronic & leptonic channels → partial chiral symmetry restoration?

φ φ 2 x 107 Pb+Pb events

ω, φ: S/B ~ 0.10 – 0.15 J/ψ: S/B 0.4 – 0.6

ω J/ψ

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Resonances (φ, ω, J/ψ) → e+e- •ShortIn medium-lived resonances: modifications of mass, width? • Compare hadronic & leptonic channels → partial chiral symmetry restoration? 2 x 107 Pb+Pb events

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Resonances (φ, ω, J/ψ) → e+e- •ShortIn medium-lived resonances: modifications of mass, width? • Compare hadronic & leptonic channels → partial chiral symmetry restoration? 2 x 107 Pb+Pb events

2 x 107 Pb+Pb events - ω, φ: significance = 12 - 15 J/ψ: significance = 40 - 50

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Soft Physics in ALICE

Event Characterization (baseline, shadowing, CGC, …. ) • Multiplicity, centrality, transverse momentum and pseudo-rapidity distributions

Bulk Properties of the Medium (T, µ, … ) • Particle ratios, hadronic resonances

Chiral Symmetry Restoration • Short-lived resonances & medium-modified masses

Collision Dynamics (space-time evolution, transport properties) • Momentum correlations (3D HBT – one of first measurements) • Collective Flow (radial, anisotropic) • Baryon number transport

Fluctuations • Event-by-event – particles, momentum, …

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 v2 Predictions for the LHC

Hirano, to check reference…. - nucl Sollfrank Heinz, Kolb, Hiranoet al , th/0701075v2

st v2 by ALICE in 1 Pb + Pb Run J.Phy.G , , and Identified particle v2 • as a function of centrality

• to at least pT = 10 GeV/c N.Borghini 35(2008) 023001 • resonances, strangeness U.A.Weidemann • including charm!

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Heavy Flavor in ALICE

Significant increase at LHC σ • Abundance of heavy flavors Rate probe early times, calculable

σcc (LHC) ~ 10 σcc (RHIC)

σbb (LHC ) ~ 100 σbb (RHIC)

Open Charm & Beauty (mass/color charge dep. of parton E-loss) • Displaced vertices (Do → K- π+ , B → e + hadrons) from TPC/ITS, TRD/EMCal • Electrons in Transition Radiation Detector (TRD)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Open Charm and Beauty  D0 → Kπ + → ππ TOF (K/π id) D K Ds → KKπ under D* → D0π study D0 → Kπρ

TPC (tracking) Λc → πKp K π ITS (vertexing)

DIS 2008 - London Andrea Dainese Courtesy27 A. Dainese Open Charm and Beauty  D0 → Kπ D+ → Kππ Ds → KKπ under D* → D0π study D0 → Kπρ TPC (tracking) Λc → πKp ITS (vertexing)  B → e+X ITS (vertexing) under B → ≥5 pr. e TPC (tracking e/π id) study B → J/ψ→ee TRD & EMCal (e/π id)

DIS 2008 - London Andrea Dainese Courtesy28 A. Dainese Open Charm and Beauty  D0 → Kπ D+ → Kππ Ds → KKπ under D* → D0π study D0 → Kπρ µ Λc → πKp MUON (tracking,id)  B → e+X under B → ≥5 pr. study B → J/ψ→ee  B → µ+X

DIS 2008 - London Andrea Dainese Courtesy29 A. Dainese Displaced Vertices: Track DCA* Resolution * Distance of Closest Approach (impact parameter with primary vertex)

Primary resolution from 2 layers of silicon pixel detector

rec. track e

Primary Vertex B

dca X

Two layers: r = 4 cm r = 7 cm

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Charm & Beauty in ALICE – RAA

+ → ππ D0 → Kπ D K

B → e + X

mC = 1.2 GeV

mC = 0

B → e Calculations: Armesto, Dainese, Salgado, Wiedemann

1 “year” at nominal luminosity mb = 4.8 GeV (107 central Pb-Pb events, 109 pp events))

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Heavy Quarks in ALICE - pt Coverage

D0 → Kπ B → e + X

electron

1 “year” at nominal luminosity (107 central Pb-Pb events, 109 pp events)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Expectations in 2010 for Heavy Quarks at LHC

D0 → Kπ 7 TeV p + p and 2.75 TeV Pb + Pb

pp Mangano, Nason, Ridolfi, NPB373 (1992) 295.

MNR with CTEQ6M + Gluon shadowing shadowing [mean of EKS98/EPS08] for Pb

Pb-Pb (0-5%) Pb-Pb (0-5%) pp pp system : 5.5 TeV 2.75 TeV 14 TeV 7 TeV √s : NN Charm/beauty Charm/beauty Charm/beauty Charm/beauty QQ σ NNQQ [mb] σ NN [mb] 3.4 / 0.14 2.1 / 0.075 11.2 / 0.5 6.9 / 0.23 QQ NtotQQ Ntot 90 / 3.7 56 / 2 0.16 / 0.007 0.10 / 0.003 EKS 98 CshadowingEKS 98 Cshadowing 0.58 / 0.77 0.60 / 0.85 -- --

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 0 2010 PbPb in ALICE – D pt Coverage

Nominal LHC year 2.75 TeV PbPb 1st year

D0 → Kπ 14 TeV 109 min. bias evts

5.5 TeV 107 5% central evts

For lower √sNN = 2.75 TeV Scale signal with cross section reduction

Bkg change from dNch/dy=6000 (PPR) to 2000 (more realistic) st Charm pT spectrum to 15 GeV/c in 1 run

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Quarkonia in ALICE Measured in both the di-electron (midrapidity, TRD, EMCal) and di-muon (forward rapidity, MUON) channels ITS (vertexing) TPC (tracking) e π e TRD & EMCal (e/ id) µ

µ MUON (tracking,id)

Courtesy A. Dainese

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington,35 May 25, 2010 The ALICE Muon Arm Muon detection Acceptance: ∆φ = 2π → – 4.0 < η < – 2.5 (θ = 2 – 9°) Absorber for hadrons and photons 10 planes of high granularity tracking Dipole Magnet (0.7 T , 3 Tm) Muon filter (4 GeV/c threshold for µ) 4 planes of trigger chambers

Muon detection in Pb + Pb Expect few hundred particles in muon chambers Maximum hit density expected ~ 0.05 cm −2 Cathode pad chambers for tracking with variable segmentation Resistive-plate chambers for trigger

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Ultimate ALICE Quarkonia Performance dNch/dy = 4000 in central Pb-Pb Bottomonia Bottomonia Particle Charmonia µ+µ- Charmonia e+e- µ+µ- e+e-

Bkg-sub mass plot

acc. η -4 < η < -2.5 |η| < 0.9 -4 < η < -2.5 |η| < 0.9 M res. 65 MeV 35 MeV 90 MeV 90 MeV S / ϒ 30, ϒ’ 12, √(S+B) J/ψ 150, ψ’ 7 J/ψ 245 ϒ 21, ϒ’ 8 (1 mo.) ϒ’’ 8 ψ, ψ’ ψ, ψ’ ϒ, ϒ’,ϒ’’ ϒ, ϒ’, no ϒ’’ 5/25/2010 pt J/ψ 0-20 GeV J/ψ 0-10 GeV ϒ 0-8 GeV -- 2010 Pb + Pb – Quarkonia in ALICE Most Optimistic Scenario (0.05 nb-1) J/ψ in 5 centrality bins

Centrality Signal Background Signal __S__ bin (103 counts) (103 counts) Background √S+B

J/ψ pT dependence up to 20 GeV/c measured in each bin J/ψ polarization ψ’ to J/ψ ratio, maybe vs centrality (tbd)

Ψ − pT dependence (no centrality dependence) Ψ’ and Ψ’’ − yields and ratios in at most 3 centrality bins

Realistic → pessimistic: J/ψ vs centrality, no ψ’; Ψ’ and Ψ’’ ratios

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 High pT Particles and Jets in ALICE

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 High pT Particles and Jet Rates in ALICE

ALICE hard probe physics capabilities: - Electron/hadron disc. (TRD, EMCal) - µ measurements (forward muon arm) - Good γ/π0 discrimination (EMCal, PHOS) - Fast trigger on jets (EMCal)

→ 0.5 nb-1 Hard Probe statistics in ALICE:

104/year in nominal minbias Pb+Pb run

inclusive jets: ET ~ 200 GeV

dijets: ET ~ 170 GeV π0: p ~ 75 GeV T PHOS x 6 lower TPC x 3 higher inclusive γ: pT ~ 45 GeV

inclusive e: pT ~ 30 GeV Thanks – Peter Jacobs

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Neutral Pion Reconstruction

Conversion electrons measured in TPC PHOS and EMCal

7 TeV p + p

PHOS PHOS

η π0

Mixed event background EMCal EMCal

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Simulated Neutral Pion Spectra in PHOS

π0 η

0 π spectra to pT ~ 30,40,50 GeV/c η spectra to pT ~ 20,35,45 GeV/c for for ∫ L dt (p+p) = 10, 100, 300 nb-1 ∫ L dt (p+p) = 10, 100, 300 nb-1

∫L dt (pp) = 10 nb-1 ~ same # binary collisions in ∫ L dt (PbPb) = 0.01 nb-1 ! 0 π spectra to pT ~ 30 GeV/c, η spectra to pT ~ 20 GeV/c

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Di-hadron Correlations in ALICE

Expectation for 1st PbPb Run:

• trigger hadron bins to > 30 GeV/c

• select ensembles of trigger/associated PID

• study centrality dependence

• determine origin!

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 What About the Ridge at LHC

Is the ridge present at LHC?

If so, investigate dependence on:

trig assoc • pT and pT

• centrality

• particle type

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Jets in Heavy Ion Collisions at RHIC & LHC

Central Au+Au √sNN=200 GeV Central Pb+Pb √sNN=5.5 TeV jet E jet ~ 120 GeV EMC + tracking data ET ~ 21 GeV EMCal + tracking sim. T

Why measure jets in heavy ion collisions? [inclusive, di-jets, hadron-jet, γ-jet,..] • Parton energy loss in High T QCD medium Requires detailed measurements for theoretical comparison / understanding Establish energy-loss mechanisms – energy flow within jets, quark vs gluon jet differences Flavor and mass dependence, fragmentation modification … • Medium response to parton energy loss – establish properties of the medium John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Considerations for Jet Reconstruction in ALICE Jet reconstruction works for tracking + EM calorimetry (from RHIC experience) • Detector resolution sufficient Systematic uncertainties understood

Many Biases (affecting jets) – take into account: • Trigger Effects (online & offline) • Event backgrounds (on average and fluctuations) • Algorithms (esp. seeded, effects on HI jet results, treatment of HI background)

• pT cuts on tracking and calorimetry

Simulations approach in ALICE (with EMCal) Utilize anti-kT (less background sensitivity) for jet reconstruction Full GEANT for detector response PYTHIA, qPYTHIA (available quenching model) for jets HIJING (central Pb+Pb at 5.5 TeV) for background Bottom-line – Consider all effects → simulate/estimate systematic uncertainties

Reduce/eliminate pT cuts, assess background & fluctuations → Background effects require delicate unfolding procedure (doable)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Jet Reconstruction in Heavy Ion Collisions

Primary Jet Reconstruction Approaches “Cone” algorithms

jet Cone-based algorithms • Cone shape restriction Fragmentation • Seeded-cone & strong trigger seed biases Hard scattering

Recombination algorithms Recombination algorithms – kT (anti-kT)

• starts from low (high) pT • merges weighted by 1/ pT (pT) → high (low) pT disfavored KT jet anti-kT jet R → resolution parameter

In Jet Reconstruction in ALICE – utilize anti-kT (less background sensitivity)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Underlying Event Background

A Bi (Ai) = Ei – ρ Ai ALICE EMCal Physics Performance Report (Nov. 2009): http://rnc.lbl.gov/Alice/wiki/ALICE_USA/Documents_files/EMCAL_PPR_DOE_November2009.pdf

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Inclusive Jets – Systematic Uncertainties* (*with EMCal)

ALICE EMCal Physics Performance Report (Nov. 2009): http://rnc.lbl.gov/Alice/wiki/ALICE_USA/Documents_files/EMCAL_PPR_DOE_November2009.pdf

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE Inclusive Jet Cross Section Measurement Capabilities with EMCal

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Jets in ALICE with EMCal: RAA

Central Pb+Pb √sNN=5.5 TeV

Jet systematic uncertainties small!

Measurements possible to 200 GeV – statistically and systematically

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Jet Broadening at RHIC & ALICE with EMCal Ratio of jet yields within R = 0.2 vs R = 0.4 using anti-KT algorithm

Central Au+Au √sNN=200 GeV Central Pb+Pb √sNN=5.5 TeV

• qPYTHIA not optimized (yet) – do not draw conclusions from shape diff’s. • Jet energy profile (AuAu data) BROADENED indicating JET QUENCHING! • Small experimental systematic uncertainties in measurements (ratios from same exp. and data set) → a precision measurement in ALICE!

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE EMCal Jet Trigger

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 Charged Jets in TPC in ALICE in 2010

Central Pb+Pb √sNN=5.5 TeV Charged jets → 1/3 of jet energy

First Year – Charged Jets Eventually – Charged + EMCal

R < 0.4 central Pb+Pb

Statistics for 1 month of Pb+Pb running (103 jets at 100 GeV in 106 Pb+Pb interactions)

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010 ALICE Prospects for “First Physics” • First physics in ALICE is NOW – pp important reference data for heavy-ions Examples: – multiplicity distribution, baryon transport – identified particle spectra – measurement of charm cross section major input to pp QCD physics

• First 105 PbPb events: global event properties – multiplicity, rapidity density, charged particle spectra – elliptic flow • First 106 PbPb events: source characteristics and spacetime evolution – identified particle spectra, resonances – differential flow analysis – particle correlations, interferometry 7 • First 10 PbPb events: high-pT and heavy flavors – suppression, “jet” quenching, heavy flavor energy loss – charmonium production • Eventual goals - bulk properties of medium & parton energy loss mechanisms – energy density, temperature, pressure – heat capacity/entropy, viscosity, sound velocity, opacity – susceptibilities, order of phase transition

John Harris (Yale) for ALICE Collaboration INT Workshop, Seattle, Washington, May 25, 2010