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Pol Bernard Gossiaux

Publications and source records attributed to Pol Bernard Gossiaux.

48 records · Page 3Linked to original sources
arXiv2014

Influence of hadronic bound states above $T_c$ on heavy-quark observables in Pb+Pb collisions at at the CERN Large Hadron Collider

We investigate how the possible existence of hadronic bound states above the deconfinement transition temperature $T_c$ affects heavy-quark observables like the nuclear modification factor, the elliptic flow and azimuthal correlations. Lattice QCD calculations suggest that above $T_c$ the effective degrees of freedom might not be exclusively partonic but that a certain fraction of hadronic degrees of freedom might already form at higher temperatures. This is an interesting questions by itself but also has a strong influence on other probes of the strongly interacting matter produced in ultrarelativistic heavy-ion collisions. A substantial fraction of hadronic bound states above $T_c$ reduces on average the interaction of the heavy quarks with colored constituents of the medium. We find that all studied observables are highly sensitive to the active degrees of freedom in the quark-gluon plasma.

hep-ph↗
arXiv2013

Semi-classical approach to $J/ψ$ suppression in high energy heavy-ion collisions

We study the heavy quark/antiquark pair dynamics in strongly-coupled quark gluon plasma. A semi-classical approach, based on the Wigner distribution and Langevin dynamics, is applied to a color screened $c{\bar c}$ pair, in a hydrodynamically cooling fireball, to evaluate the total $J/ψ$ suppression at both RHIC and LHC energies. Although its limitation is observed, this approach results to a $J/ψ$ suppression of around 0.30 at RHIC and 0.25 at LHC.

hep-ph↗
arXiv2012

Heavy quark quenching from RHIC to LHC and the consequences of gluon damping

In this contribution to the Quark Matter 2012 conference, we study whether energy loss models established for RHIC energies to describe the quenching of heavy quarks can be applied at LHC with the same success. We also benefit from the larger $p_T$-range accessible at this accelerator to test the impact of gluon damping on observables such as the nuclear modification factor.

hep-ph↗
arXiv2012

Plasma damping effects on the radiative energy loss of relativistic particles

The energy loss of a relativistic charge undergoing multiple scatterings while traversing an infinite, polarizable and absorptive plasma is investigated. Polarization and damping mechanisms in the medium are phenomenologically modelled by a complex index of refraction. Apart from the known Ter-Mikaelian effect related to the dielectric polarization of matter, we find an additional, substantial reduction of the energy loss due to damping of radiation. The observed effect is more prominent for larger damping and/or larger energy of the charge. A conceivable analog of this phenomenon in QCD could influence the study of jet quenching phenomena in ultra-relativistic heavy-ion collisions at RHIC and LHC.

hep-ph↗
arXiv2012

Radiative energy loss in the absorptive QGP: taming the long formation lengths in coherent emission

In an absorptive plasma, damping of radiation mechanisms can influence the bremsstrahlung formation in case of large radiation formation lengths. We study qualitatively the influence of this effect on the gluon bremsstrahlung spectrum off heavy quarks in the quark-gluon plasma. Independent of the heavy-quark mass, the spectrum is found to be strongly suppressed in an intermediate gluon energy region which grows with increasing gluon damping rate and increasing energy of the heavy quark. Thus, just as polarization effects in the plasma render the bremsstrahlung spectra independent of the quark mass in the soft gluon regime, damping effects tend to have a similar impact for larger gluon energies.

hep-ph↗
arXiv2012

Recent results on heavy quark quenching in ultrarelativistic heavy ion collisions

In this contribution, we present some predictions for the production of D and B mesons in ultrarelativistic heavy ion collisions at RHIC and LHC energies and confront them with experimental results obtained so far by the STAR, PHENIX, ALICE and CMS collaborations. We next discuss some preliminary results obtained with an improved description of the medium based on EPOS initial conditions, and its possible implications on the nuclear modification factor and on the elliptic flow of heavy quarks.

hep-ph↗
arXiv2012

Radiative energy loss reduction in an absorptive plasma

The influence of the damping of radiation on the radiative energy loss spectrum of a relativistic charge in an infinite, absorptive plasma is studied. We find increasing reduction of the spectrum with increasing damping. Our studies, which represent an Abelian approximation for the colour charge dynamics in the quark-gluon plasma, may influence the analysis of jet quenching phenomena observed in high-energy nuclear collisions. Here, we focus on a formal discussion of the limiting behaviour with increasing radiation frequency. In an absorptive (and polarizable) medium, this is determined by the behaviour of the exponential damping factor entering the spectrum and the formation time of radiation.

hep-ph↗
arXiv2011

Heavy Quark Energy Loss in High Multiplicity Proton Proton Collisions at LHC

One of the most promising probes to study deconfined matter created in high energy nuclear collisions is the energy loss of (heavy) quarks. It has been shown in experiments at the Relativistic Heavy Ion Collider (RHIC) that even charm and bottom quarks, despite their high mass, experience a remarkable medium suppression in the Quark Gluon Plasma. In this exploratory investigation we study the energy loss of heavy quarks in high multiplicity proton-proton collisions at LHC energies. Although the colliding systems are smaller than compared to those at RHIC (p+p vs. Au+Au) the higher energy might lead to multiplicities comparable to Cu+Cu collisions at RHIC. Recently the CMS collaboration has shown that these particles likely interact among each other. The interaction of charm quarks with this environment gives rise to a non-negligible suppression of high momentum heavy quarks in elementary collisions.

hep-ph↗
arXiv2011

The influence of bulk evolution models on heavy-quark phenomenology

We study the impact of different Quark-Gluon Plasma expansion scenarios in heavy-ion collisions on spectra and elliptic flow of heavy quarks. For identical heavy-quark transport coefficients relativistic Langevin simulations with different expansion scenarios can lead to appreciable variations in the calculated suppression and elliptic flow of the heavy-quark spectra, by up to a factor of two. A cross comparison with two sets of transport coefficients supports these findings, illustrating the importance of realistic expansion models for quantitative evaluations of heavy-quark observables in heavy-ion collisions. It also turns out that differences in freeze-out prescriptions and Langevin realizations play a significant role in these variations. Light-quark observables are essential in reducing the uncertainties associated with the bulk-matter evolution, even though uncertainties due to the freeze-out prescription persist.

hep-ph↗
arXiv1997

The importance of initial-final state correlations for the formation of fragments in heavy ion collisions

Using quantum molecular dynamics simulations, we investigate the formation of fragments in symmetric reactions between beam energies of E=30AMeV and 600AMeV. After a comparison with existing data we investigate some observables relevant to tackle equilibration: dsigma/dErat, the double differential cross section dsigma/pt.dpz.dpt,... Apart maybe from very energetic E>400AMeV and very central reactions, none of our simulations gives evidence that the system passes through a state of equilibrium. Later, we address the production mechanisms and find that, whatever the energy, nucleons finally entrained in a fragment exhibit strong initial-final state correlations, in coordinate as well as in momentum space. At high energy those correlations resemble the ones obtained in the participant-spectator model. At low energy the correlations are equally strong, but more complicated; they are a consequence of the Pauli blocking of the nucleon-nucleon collisions, the geometry, and the excitation energy. Studying a second set of time-dependent variables (radii, densities,...), we investigate in details how those correlations survive the reaction especially in central reactions where the nucleons have to pass through the whole system. It appears that some fragments are made of nucleons which were initially correlated, whereas others are formed by nucleons scattered during the reaction into the vicinity of a group of previously correlated nucleons.

nucl-th↗