"Jets" and their distortion in heavy-ion collisions

After a discussion on the meaning of "jets" in the context of nucleus-nucleus collisions, the distortions of the profile of a parton shower induced by the presence of a medium is investigated in a QCD-inspired model that implements the conservation of energy at each step of the shower evolution.Comment: 10 pages, 4 figures; talk given at the workshop "High-pT physics at LHC 2009", February 4-7, Prague, Czech Republi

Multiparticle correlations and momentum conservation in nucleus-nucleus collisions

Particle correlations are very actively studied in heavy-ion collisions at ultra-relativistic energies. Here, an attempt is made at determining a proper reference for such studies, by taking properly into account the multiparticle correlations induced by the conservation of total momentum in the collisions.Comment: 9 pages, talk given at the workshop "High-pT physics at LHC", March 23-27, 2007, Jyvaskyla, Finland. v2: final versio

Dynamical evolution of heavy quarkonia in a deconfined medium

We investigate some consequences of the possibility that heavy quarkonia in a quark-gluon plasma possess different (quasi-) bound states, between which transitions are possible. In particular, we show that the time-evolution eigenstates in the medium are mixtures of the vacuum eigenstates. This leads to abundance ratios of quarkonia that differ from those predicted in statistical models or in the sequential-melting picture.Comment: 5 pages, 3 figure

Predictions for the LHC heavy ion programme

Apparently universal trends have been observed in relativistic nucleus-nucleus collisions up to RHIC energies. Here, we review these trends and we discuss their agnostic extrapolation to heavy ion collisions at the LHC.Comment: 37 pages, 6 figures; invited topical review for Journal of Physics

Distorting the Hump-backed Plateau of Jets with Dense QCD Matter

The hump-backed plateau of the single inclusive distribution of hadrons inside a jet provides a standard test of the interplay between probabilistic parton splitting and quantum coherence in QCD. The medium-induced modification of this QCD radiation physics is expected to give access to the properties of the dense medium produced in relativistic heavy ion collisions. Here, we introduce a formulation of medium-induced parton energy loss, which treats all leading and subleading parton branchings equally, and which - for showering in the vacuum - accounts for the observed distribution of soft jet fragments. We show that the strong suppression of single inclusive hadron spectra measured in Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) implies a characteristic distortion of the hump-backed plateau; we determine, as a function of jet energy, to what extent the soft jet fragments can be measured above some momentum cut. Our study further indicates that the approximate pT-independence of the measured nuclear modification factor does not exclude a significant Q^2-dependence of parton energy loss.Comment: 4 pages RevTex, 3 eps-figure

Momentum conservation and correlation analyses in heavy-ion collisions at ultrarelativistic energies

Global transverse-momentum conservation induces correlations between any number of particles, which contribute in particular to the two- and three-particle correlations measured in heavy-ion collisions. These correlations are examined in detail, and their importance for studies of jets and their interaction with the medium is discussed.Comment: 5 pages, 2 figures. v2: corrected typos and added a paragrap

Anisotropic flow in the few collisions regime: application to bottomonia

Considering the kinetic Boltzmann equation in the limit of very few collisions, we study the evolution of the phase space distribution of bottomonia interacting with an expanding gas of massless partons. We investigate the scaling of the anisotropic flow coefficients on the initial eccentricities and the inverse Knudsen number, and compute their transverse momentum dependence.Comment: 4 pages, 1 figure, Presented by N.K. at Hot Quarks 2018 - Workshop for young scientists on the physics of ultrarelativistic nucleus-nucleus collisions, Texel, The Netherlands, September 7-14 2018, Submitted to MDPI Proceedings. v2: Figure corrected + minor change

Flow analysis from cumulants: a practical guide

We have recently proposed a new method of flow analysis, based on a cumulant expansion of multiparticle azimuthal correlations. Here, we describe the practical implementation of the method. The major improvement over traditional methods is that the cumulant expansion eliminates order by order correlations not due to flow, which are often large but usually neglected.Comment: 6 pages revtex. Proceedings of the International Workshop on the Physics of the Quark-Gluon Plasma, Palaiseau, France, 4-7 Sept. 0

Thermalization and elliptic flow at RHIC

We discuss signatures of thermalisation in heavy ion collisions based on elliptic flow. We then propose a new method to analyse elliptic flow, based on multiparticle azimuthal correlations. This method allows one to test quantitatively the collective behaviour of the interacting system.Comment: 6 pages, talk given at XXXI International Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. URL http://ismd31.ccnu.edu.cn