News from ALICE Jan PLUTA Heavy Ion Reaction Group (HIRG) Warsaw University of Technology February 22, XIII GDRE Workshop, SUBATECH, Nantes

2 2 Detector: Size: 16 x 26 metres Weight: 10,000 tons Collaboration: > 1000 Members > 100 Institutes > 30 countries Technologies:18 Tracking:7 PID:6 Calo.:5 Trigger, N ch :11 2February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes ALICE web page

February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes 3 ALICE - PHYSICS WORKING GROUPS PWG-PP Detector Performance PWG-CF Correlations Fluctuations Bulk PWG-DQ Dileptons and Quarkonia PWG-HF Heavy Flavour PWG-GA photon and pion working group PWG-LF Light Flavour Spectra PWG-JE Jets Ultraperipheral, DiffractivePWG-UD

4 v2(pt) for the centrality bin 40-50% from the 2 - and 4-particle cumulant methods for this measurement and for Au-Au collisions at 200 GeV. b) v2{4}(pt) for various centralities compared to STAR measurements. No flow contributions to v2{4} are negligible Contribution from flow fluctuations is positive for v2{2} and negative for v2{4} Value of v2(pt) does not change within uncertainties from 200 GeV to 2.76 TeV The transverse momentum dependence is qualitatively similar for all three centrality classes. February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes 1) PWG-CF Correlations Fluctuations Bulk

5 Elliptic flow integrated over the Pt range 0:2 < pt < 5:0 GeV/c, as a function of event centrality The larger integrated elliptic flow at the LHC is caused by the increase in the mean pt. February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

6 Integrated elliptic flow at 2.76 TeV in Pb-Pb 20-30% centrality class compared with results from lower energies February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

7 Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at √sNN = 2.76 TeV Anisotropic flow provides valuable information on the particle production mechanism in different transverse momentum  pt < 2−3 GeV/c - hydrodynamic model calculations  3 < pt < 6 GeV/c - flow of the baryons is larger than that of the mesons  pt > 8 GeV/c - the fragmentation of high-energy partons, resulting from initial hard scatterings, is expected to play the dominant role. While traversing the hot and dense matter these partons experience collisional and radiative energy loss Due to event-by-event fluctuations of the positions of the participating nucleons inside the nuclei, the shape of the initial energy density of the heavy-ion collision in general is not symmetric with respect to the reaction plane and the  n may deviate from the reaction plane February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

8 Unidentified charged particle v2, v3, and v4 as a function of transverse momentum for different centrality classes. WHDG model calculations for v2 of neutral pions including collisional and radiative energy loss of partons February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

9 Unidentified charged particle v2, v3, and v4 integrated over the transverse momentum range 10 < pt < 20 GeV/c as a function of collision centrality February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

10 v2 (top) and v3 (bottom) of charged pion and proton as a function of transverse momentum for 10-50% centrality class compared to unidentified charged particles results from the event plane method. Particle type dependence, which is typical at low pt, persists out to high transverse momenta. February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

11 Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb collisions at psNN = 2.76TeV Distributions of central and peripheral Pb–Pb collisions compared to that of pp collisions. February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes 2)

12 Yield ratio I CP Yield ratio I AA for central (0-5% Pb–Pb/pp) and peripheral (60-90% Pb– Pb/pp) collisions using the three background subtraction schemes In central collisions, on the away-side - a suppression is observed as expected from strong in-medium energy loss. On the near-side, a significant enhancement is observed for the first time. February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

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Charged particle R AA Difference of peripheral and central seen in pt distributions Stronger parton energy loss in central collisions compared to RHIC Clear increase for p T > 7 GeV/C ! Not observed in RHIC PLB 696, 30 (2011) 15February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

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Particle ratios – from RHIC to LHC 23 At LHC particle-antiparticle ratios at mid-rapidity are compatible with 1, as expected. No centrality dependence was observed  μ B ~ 0 STAR, PRC 79, (2009) PHENIX, PRC 69, (2004) BRAHMS, PRC 72, (2005) February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

Strangeness enhancement 24 Strangeness enhancements with respect to pp collisions increases following hierarchy of strangeness content February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

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The future 28 ● 2012: p-Pb and Pb-p initial state effects, shadowing, nuclear absorption,... ● : LHC long shutdown 1 ● : FULL ENERGY !! 7 TeV, √sNN = 5.5 TeV ● 2018: LHC long shutdown 2 ● ≥ 2019: HIGH LUMINOSITY → 50 kHz Pb-Pb collisions LHC experiment upgrades to cope with the higher rates!! New vertex detectors Faster readout, pipelining, high level triggers, TPC with continuous readout... February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes

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32 Wait much more from Alice in future JP Wait much more from Alice in future JP February 22, 2016 XIII GDRE Workshop, SUBATECH, Nantes