1. ALICE and the Little Bang
QCD phase transition (QGP  hadrons) at tUniverse ~10 ms
In high-energy heavy-ion collisions, large energy densities (> 2–3 GeV/fm3) are reached over large volumes (>> 100 fm3)
Temperature
Baryonic
density
U. Heinz
Big Bang
Little Bang
high temperature
high energy density
low baryonic density
quark-gluon
plasma
formation of nucleons
formation of nuclei
208Pb
208Pb
Rencontres de Physique, La Thuile, Andrea Dainese

2. ALICE apparatus and datasets
Two main parts:
barrel (|h|<0.9), B = 0.5 Tesla
forward muon spectrometer, -4<h<-2.5
Crucial for HF:
vertexing, tracking
hadron and lepton ID
Datasets used for the
results shown here:
Pb-Pb collision centrality determination: Glauber model analysis of large-h V0 scintillator amplitudes
MB trigger (Pixel, V0)
system, √sNN (TeV) pp 7
pp 2.76
Pb-Pb
2.76
year
2010
2011
NMB M
65 M
17 M
Hot and dense QCD at LHC, Santiago, Andrea Dainese 2

3. D mesons cross sections: pp 7 TeV, D0, D+, D*, |y|<0.5
JHEP 01 (2012) 128
FONLL: Cacciari et al., private comm.
GM-VFNS: Kniehl et al., private comm.
1 < pt < 24 GeV/c, with 5 nb-1 (2010 statistics)
pQCD predictions (FONLL and GM-VFNS) compatible with our data
Hot and dense QCD at LHC, Santiago, Andrea Dainese

4. More charm in pp 7 TeV: Ds and Lc
D ratios
in agreement
with other exp’s
Hot and dense QCD at LHC, Santiago, Andrea Dainese

5. The Total Charm Cross Section in pp
Extrapolation from pt = 2 GeV/c to 0 (about ×2) and full y using FONLL
7 TeV
2.76 TeV
Consistent comparison with NLO over 3 orders of magnitude
Quark Matter 2011, Annecy, Andrea Dainese

6. Heavy flavour decay leptons: pp 7 TeV, e in |y|<0. 8 & m in 2
Heavy flavour decay leptons: pp 7 TeV, e in |y|<0.8 & m in 2.5<y<4
Cocktail of “photonic” backgrounds based on measured p0 cross section
Inclusive – Cocktail: electrons from c and b decays
Agrees with measured-D decay electron spectrum at low pt
arXiv: (acc. by PLB)
Measured ds/dpt in 2-12 GeV/c
FONLL indicates beauty dominance above 6 GeV/c
Hot and dense QCD at LHC, Santiago, Andrea Dainese

7. D pt distributions in Pb-Pb
Strong suppression observed in central collisions (0-20%) wrt scaled pp reference
Significant suppression also in semiperipheral (40-80%) wrt scaled pp reference
Hot and dense QCD at LHC, Santiago, Andrea Dainese

8. D meson nuclear modification factor RAA in central Pb-Pb collisions
Suppression for charm is a factor 3-4 above 5 GeV/c
Indicates strong energy loss of c quarks in the hot and dense QCD medium formed in these collisions
Hot and dense QCD at LHC, Santiago, Andrea Dainese

9. Background-subtracted Electron RAA
Inclusive electrons – background sources
low pt: large systematic uncertainties (also from pp reference)
above 3-4 GeV/c: dominated by charm and beauty decays
Suppression in central collisions: factor 1.5-4
Peripheral collisions
Central collisions
Hot and dense QCD at LHC, Santiago, Andrea Dainese

10. Muons at forward rapidity: central-to-peripheral nuclear modification factor
0-10%/40-80% suppression ~2.5 above 6 GeV/c
According to FONLL, beauty dominant in this region
Hot and dense QCD at LHC, Santiago, Andrea Dainese

11. J/ polarization results
ALICE Coll., arXiv: ,
accepted by PRL
M.Butenschoen, A.Kniehl, arXiv:
First result at the LHC: almost no polarization for the J/
First theoretical calculation (NLO NRQCD) compared to data:
promising result, reasonable agreement with theory

12. Results on J/ yield vs multiplicity
ALICE Collaboration arXiv:
pp multiplicity similar to Cu-Cu collisions at RHIC
Linear increase with dNch/d
Similar behaviour in two different rapidity ranges
Stronger effect at y=0?

13. J/ in Pb-Pb: results and comparison with RHIC
ALICE Collaboration arXiv:
ALICE, LHC, forward rapidity
PHENIX, RHIC, mid-rapidity
PHENIX, RHIC, forward rapidity
rapidity:
RAA(ALICE) > RAA (PHENIX)
Smaller J/ suppression in spite of the factor 13 in s
First indication for charm quark (re)combination in
heavy-ion collisions