Gianluca Aglieri Rinella

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at root S-NN=2.76 TeV

Article history: Received 28 May 2012 Received in revised form 28 November 2012 Accepted 28 December 2012 Available online 4 January 2013 Editor: V. Metag The elliptic, v2, triangular, v3, and quadrangular, v4, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in Pb–Pb collisions at √ sNN = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range |η| < 0.8 at different collision centralities and as a function of transverse momentum, pT, out to pT = 20 GeV/c. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for pT > 8 GeV/c. The small pT dependence of the difference between elliptic flow results obtained from the event plane and fourparticle cumulant methods suggests a common origin of flow fluctuations up to pT = 8 GeV/c. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least pT = 8 GeV/c indicating that the particle type dependence persists out to high pT.

J/Ψ production and nuclear effects in p-Pb collisions at √sNN=5.02 TeV

Inclusive J/psi production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy = 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < y (cms) < 3.53 and -4.46 < y (cms) < -2.96, down to zero transverse momentum, studying the mu (+) mu (-) decay mode. In this paper, the J/psi production cross section and the nuclear modification factor R (pPb) for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/psi yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.A bstractInclusive J/ψ production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy

Particle-Yield Modification in Jetlike Azimuthal Dihadron Correlations in Pb-Pb Collisions at root S-NN=2.76 TeV

\sqrt{{{s_{\mathrm{NN}}}}}

Measurement of charged jet suppression in Pb-Pb collisions at √s NN = 2.76 TeV

= 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < ycms< 3.53 and −4.46 < ycms< −2.96, down to zero transverse momentum, studying the μ+μ− decay mode. In this paper, the J/ψ production cross section and the nuclear modification factor RpPb for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/ψ yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.

Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV

The yield of charged particles associated with high-p(t) trigger particles (8<p(t)<15 GeV/c) is measured with the ALICE detector in Pb-Pb collisions at √s(NN)=2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jetlike correlation peaks in azimuthal dihadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta p(t)>3 GeV/c on the away side drops to about 60% of that observed in pp collisions, while on the near side a moderate enhancement of 20%-30% is found.

Production of light nuclei and anti-nuclei in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

A bstractA measurement of the transverse momentum spectra of jets in Pb-Pb collisions at

Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions

\sqrt{{{s_{\mathrm{NN}}}}}

Performance study of new pixel hybrid photon detector prototypes for the LHCb RICH counters

= 2.76TeV is reported. Jets are reconstructed from charged particles using the anti-kT jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |η| < 0.5. The transverse momentum pT of charged particles is measured down to 0.15 GeV/c which gives access to the low pT fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R = 0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high pT leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R = 0.2 and R = 0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R < 0.3.

Measurement of electrons from beauty hadron decays in pp collisions at root s=7 TeV

A bstractThe ALICE experiment at the LHC has studied J/ψ production at mid-rapidity in pp collisions at

Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at sNN=2.76 TeV

\sqrt{s}=7