1. 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

2. 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

3. 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

4. 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

5. 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?

6. 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

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

8. 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

9. 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 ~ 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)

10. 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

11. } 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

12. 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

13. 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 ~ ( ) 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.

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

15. 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!!

16. 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

17. 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)

18. From here to…

19. You are welcome to join the UCT-iThemba-ALICE Collaboration!

20. Backup Slides

21. 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:

22. Parity Violation in W Decaysμ-
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

23. 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).