ALICE: A STATUS REPORT AND SOUTH AFRICA’S INVOLVEMENT S.V. FÖRTSCH FOR THE ALICE COLLABORATION More than 1000 Members from 109 Institutions in 31 Countries will study the ‘State of Matter’ at the LHC making use of p-p, p-A and A-A Collisions in A Large Ion Collider Experiment

Studying the Quark Gluon Plasma in Heavy Ion Collisions QCD Coupling Constant QCD Matter Phase Diagram Confinement S Bethke, Prog. Part. Nucl. Phys. 58, 351, 2007 Asymptotic Freedom Z Conesa del Valle, PhD thesis 2007

Where to look for the Quark Gluon Plasma Phase Transition from Hadronic Matter to QGP with Lattice QCD Deconfinement Chiral Symmetry Energy Density LHC RHIC F Karsch, E Laermann, Phys Rev D50, 6954, 1994 SPS Tc ~ 170 – 192 MeV at μ = 0 Z Conesa del Valle, PhD thesis 2007

The Quark-Gluon Plasma Evolution of an Ultra-relativistic Heavy-Ion Collision Freeze-out Hadronisation } Chrial symmetry Thermal equilibrium Chemical equilibrium Deconfinement t Thermalization Z Z Conesa del Valle, PhD thesis 2007

Probing the Quark Gluon Plasma Increasing Energy Densities: AGS → SPS → RHIC → LHC SPS AGS Evidence for the Formation of a New State of Matter: QGP Is there yet another unusual State of Matter: CGC?

Anomalous J/Ψ Suppression CERN-SPS Heavy-Ion Program: p-p, p-A, A-A, A-B collisions at √s = 9 – 17 GeV Nuclear Matter Absorption P. Pillot et al., AIP Conf Proc, 806:279, 2006 Charmonium Suppression in Central Collisions (Large L Values) => Deconfined Medium

Elliptic Flow RHIC Experiments: d-d, d-Au, Cu-Cu, Au-Au collisions at √s = 19 - 200A GeV Azimuthal Anisotropy Z Conesa del Valle, PhD thesis 2007 J Adams et al., PRC72, 014904, 2005 Perfect Liquid (Strongly Interacting Liquid) or Ideal-gas QGP?

Jet Quenching High-pT Particle Suppression @RHIC In-Medium Effects => Nuclear Modification Factor R S Adler et al., PRL 91:072303, 2003 Deconfined Medium with high Gluon Density => Large Parton Energy Loss

Heavy Quarks as QGP Probes SPS Pb-Pb Cent RHIC Au-Au Cent LHC p-p N(cc) 0.2 10 115 N(bb) - 0.05 0.007 5 Z Conesa del Valle, PhD thesis 2007 Production in nucleon-nucleon collisions Production time p ~ 0.05 - 0.15 fm/c Predominant processes: gluon fusion and q-qbar annihilation Nuclear medium influence: p-A collisions Shadowing Gluon saturation Effects in a QGP: A-B collisions Energy loss in the QGP (high pt) Thermalization in the QGP (low pt) Why at LHC? They will be abundantly produced Sensitivity to charm energy loss but also to beauty energy loss Low Bjorken-x values (10-3,10-5)

Physics at the LHC Generation of Mass: QGP Broken Symmetries: Chiral Symmetry Broken Symmetries: CP Symmetry Generation of Mass: Higgs Broken Symmetries: SuperSymmetry p-p Pb-Pb Ar-Ar p-Pb √sNN [TeV] 14 5.5 6.3 8.8 ‹L›[cm-2s-1] 3.1030 5.1026 1029 Rate [s-1] 2.105 4.103 3.105 Runtime [s] 107 106 σgeom 0.07 7.7 2.7 1.9 Z Conesa del Valle, PhD thesis 2007

} ALICE Set-up TOF TRD HMPID ITS PMD Muon Arm PHOS TPC Size: 16 x 26 meters Weight: 10,000 tons TOF TRD HMPID Forward Detectors ZDC FMD (5×104 channels) V0 T0 Very different Design than other three LHC Experiments (ATLAS, CMS &LHCb). Has to identify and track particles of ~100 MeV/c  pT  ~100 GeV/c to reconstruct short-lived particles such as hyperons, D and B mesons. Designed to cope with Particle Multiplicities of up to 8000 for Pb-Pb reactions with complex trigger selectivity. Run with Heavy-ion beams at relatively low event rates ( 10 k Hz at L = 1027 cm-2 s-1), short running time but large event size. In p-p or p-A running mode rates are up to 200 kHz, longer running time and smaller event size ITS } PMD Hadrons Muons, Electrons Photons Muons (-4.0  η  -2.4) -0.9  η  0.9 Muon Arm PHOS Rapidity: Added since 1997: V0/T0/ACORDE TRD(’99) EMCAL (’06) ALICE Set-up TPC

Time Evolution at the LHC nucleons collide weak boson is produced Nucleon-Nucleon collisions weak boson decays 0.101 0.001 time [fm/c] 1 1.1 11.1 time [fm/c] Weak bosons are produced and decay before the QGP is formed. Their decay products travel through the QGP ! They behave as medium blind references ! nuclei collide Nucleus-Nucleus collisions characteristic time of the strong interaction Z Conesa del Valle, Physics Forum, ALICE Week 29/10/08 QGP lifetime

Why Study weak Bosons at LHC? They are produced in initial hard collisions p ~ 10-3 fm/c, and decay in d ~ 0.1 fm/c. They are the standard model « candles ». They will allow: Luminosity measurements. Probe the PDFs (coll.p-p) and the nuclear modification effects (coll. p-A) in the Bjorken-x domain of x ~ (10-4-10-3) at Q2 ~ m2W,Z In a first approximation they do not interact with the QGP, so: Their production will allow to test the validity of the binary scaling (with the number of N-N collisions); They could be the references to observe the medium induced effects (by the QGP) in other probes, such as the high pt heavy quark energy loss.

Di-Muon Spectrometer Dipole Magnet Trigger Chambers Absorber Tracking Chambers Iron wall

Study of W± Production in HIC with the ALICE Muon Spectrometer Muonic Decay: W+ (W-) → μ+ (μ-) νμ (νμ) BR=10% pT ~ MW/2 Distinguish μ+ from μ-: Study W+ / W- Production Asymmetry Simulations with Pythia and ALIROOT: Use p-p, p-n, n-n Collisions Z Conesa del Valle, PhD thesis 2007 Note Parity Violation!!

Study of W± Production… continued Charmed Decay: W± → c X → ··· → μ± Y BR=33% Lower pT due to c-Quark fragmentation into D hadrons All reconstructed muons Ratio of μ+ / μ- Z Conesa del Valle, PhD thesis 2007 Possible Signature for quark/gluon Shadowing (μW / μ(c,b)) Charge Asymmetry: Signature of W production Need dHLT to Introduce hight pT Cut → SA’s Involvement See Talk by Z. Buthelezi

Status and Outlook UCT-iThemba-ALICE Collaboration under auspices of SA-CERN Program => Official Launch on 15 December 2008 at iThemba LABS According to MOU: Participation in (Online / Offline) Di-muon HLT, Di-muon Group Pre-commissioning of Detectors, Cosmic Runs Priority for first Detector Configuration: TPC+SPD+V0 First Beam: Beginning of May 2009 Ep = 450 GeV (Beam-gas Interactions => Background checks) First Collisions: √sNN = 900 GeV (Consistency Checks) Then √sNN = 10 TeV (First New Physics!!), √sNN = 14 TeV (p-p), √sNN = 5.5 TeV (Pb-Pb) (End of 2009)

From here to…

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Backup Slides

Binary Scaling In Absence of Nuclear effects Heavy-Quark Production Yields scale from p-p → A-A Collisions according to ‹Ncoll› of inelastic N-N Collisions (Binary Scaling). In-Medium Energy Loss of Heavy Quarks → Suppression of High-pT Muon Yield with respect to Binary-scaled Yields. Suppression  Nuclear Modification Factor RAA:

Parity Violation in W Decays μ- Left-handed q (valence) q' (sea) W- μ+ Right-handed Conservation of Momentum and Helicity q (valence) q' (sea) W+ Z Conesa del Valle, PhD thesis 2007

Why Study weak Bosons at LHC? Weak Bosons (Z0, W±) are produced in p-p and A-A collisions before QGP is formed due to large Mass Decay either before or within QGP (0.08, 0.09 fm/c) In LO Approximation: q + q' → W± q + q → Z Characterized by Q2 = M2 “Standard Candles” for Luminosities => Known Production Cross-Sections. Will be sensitive to Quark Parton Distribution Functions at large Q2 in p-p Collisions. Study Quark Nuclear Modification Effects in p-A Collisions. Leptonic Decay will be Calibration of Muon Nuclear Modification Factor and Test of Binary Scaling Assumption in A-A Collisions. Can be used as a Reference to study Medium-induced Effects e.g. Suppression of High pT of Decay Muons from Charm, Beauty and Jet Quenching (Z).