Searcharxiv⌕ Search

arXiv subjects

F. Gelis

Publications and source records attributed to F. Gelis.

At least 19 recordsLinked to original sources
arXiv2016

Quark production in heavy ion collisions I. Formalism and boost invariant fermionic light-cone mode functions

We revisit the problem of quark production in high energy heavy ion collisions, at leading order in $α_s$ in the color glass condensate framework. In this first paper, we setup the formalism and express the quark spectrum in terms of a set of mode functions of the Dirac equation. We determine analytically their initial value in the Fock-Schwinger gauge on a proper time surface $Q_sτ_0\ll 1$, in a basis which makes manifest the boost invariance properties of this problem. We also describe a statistical algorithm to perform the sampling of the mode functions.

hep-ph↗
arXiv2013

Formulation of the Schwinger mechanism in classical statistical field theory

In this paper, we show how classical statistical field theory techniques can be used to efficiently perform the numerical evaluation of the non-perturbative Schwinger mechanism of particle production by quantum tunneling. In some approximation, we also consider the back-reaction of the produced particles on the external field, as well as the self-interactions of the produced particles.

hep-ph↗
arXiv2013

Predictions for $p+$Pb Collisions at sqrt s_NN = 5 TeV

Predictions for charged hadron, identified light hadron, quarkonium, photon, jet and gauge bosons in p+Pb collisions at sqrt s_NN = 5 TeV are compiled and compared. When test run data are available, they are compared to the model predictions.

hep-ph↗
arXiv2012

Color Glass Condensate and Glasma

We review the Color Glass Condensate effective theory, that describes the gluon content of a high energy hadron or nucleus, in the saturation regime. The emphasis is put on applications to high energy heavy ion collisions. After describing initial state factorization, we discuss the Glasma phase, that precedes the formation of an equilibrated quark-gluon plasma. We end this review with a presentation of recent developments in the study of the isotropization and thermalization of the quark-gluon plasma.

hep-ph↗
arXiv2012

Next-to-Leading Order correction to inclusive particle spectra in the Color Glass Condensate framework

In [arXiv:0804.2630], we have analyzed the leading logarithms of energy that appear in the inclusive spectrum of gluons produced in heavy ion collisions, calculated in the Color Glass Condensate framework. The main result of this paper was that these logarithms are intrinsic properties of the colliding projectiles, and that they can be resummed by letting the distributions of color sources in the nuclei evolve according to the JIMWLK equation. An essential step in the proof of this factorization result is the calculation of the gluon spectrum at Next-to-Leading order, and in particular a functional relationship that expresses the NLO correction as the action of a certain operator on the LO spectrum. In this paper, we show that this type of relation between spectra at LO and NLO is not specific to the production of gluons, but that it is in fact generic for inclusive spectra in heavy ion collisions. To illustrate this, we compute up to NLO the inclusive spectrum of some hypothetical scalar fields, either color neutral or colored, that couple to gluons.

hep-ph↗
arXiv2012

Initial state and thermalization

We report recent results on the role of instabilities in the isotropization and thermalization of a longitudinally expanding system of quantum fields.

hep-ph↗
arXiv2011

Gluons and the quark sea at high energies: distributions, polarization, tomography

This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

nucl-th↗
arXiv2011

Role of quantum fluctuations in a system with strong fields: Spectral properties and Thermalization

In a previous work [arXiv:1009.4363], we have studied the evolution of a scalar field with a quartic coupling, driven by a classical source that initializes it to a non-perturbatively large value. At leading order in the coupling, the evolution of this system is given by classical solutions of the field equation of motion. However, this system is subject to a parametric resonance that leads to secular divergences in higher order corrections to physical observables. We have proposed a scheme that resums all the leading secular terms: this resummation leads to finite results at all times, and we have observed also that it makes the pressure tensor of the system relax to its equilibrium value. In the present paper, we continue the study of this system by looking at finer details of its dynamics. We first compute its spectral function at various stages of the evolution, and we observe that after a fairly short transient time there are well defined massive quasi-particles. We then consider the time evolution of the momentum distribution of these quasi-particles, and we show that after a stage dominated by the parametric resonance, this distribution slowly evolves to an equilibrium distribution. Interestingly, this distribution develops a transient chemical potential, signalling the fact that number changing processes are much slower than the elastic ones.

hep-ph↗
arXiv2011

Proton-Nucleus Collisions at the LHC: Scientific Opportunities and Requirements

Proton-nucleus (p+A) collisions have long been recognized as a crucial component of the physics programme with nuclear beams at high energies, in particular for their reference role to interpret and understand nucleus-nucleus data as well as for their potential to elucidate the partonic structure of matter at low parton fractional momenta (small-x). Here, we summarize the main motivations that make a proton-nucleus run a decisive ingredient for a successful heavy-ion programme at the Large Hadron Collider (LHC) and we present unique scientific opportunities arising from these collisions. We also review the status of ongoing discussions about operation plans for the p+A mode at the LHC.

hep-ph↗
arXiv2011

Effective potential in the BET formalism

We calculate the one-loop effective potential at finite temperature for a system of massless scalar fields with quartic interaction $λϕ^4$ in the framework of the boundary effective theory (BET) formalism. The calculation relies on the solution of the classical equation of motion for the field, and Gaussian fluctuations around it. Our result is non-perturbative and differs from the standard one-loop effective potential for field values larger than $T/\sqrtλ$.

hep-ph↗
arXiv2010

Role of quantum fluctuations in a system with strong fields: Onset of hydrodynamical flow

Quantum fluctuations are believed to play an important role in the thermalization of classical fields in inflationary cosmology but their relevance for isotropization/thermalization of the classical fields produced in heavy ion collisions is not completely understood. We consider a scalar $ϕ^4$ toy model coupled to a strong external source, like in the Color Glass Condensate description of the early time dynamics of ultrarelativistic heavy ion collisions. The leading order classical evolution of the scalar fields is significantly modified by the rapid growth of time-dependent quantum fluctuations, necessitating an all order resummation of such "secular" terms. We show that the resummed expressions cause the system to evolve in accordance with ideal hydrodynamics. We comment briefly on the thermalization of our quantum system and the extension of our results to a gauge theory.

hep-ph↗
arXiv2010

The Color Glass Condensate

We provide a broad overview of the theoretical status and phenomenological applications of the Color Glass Condensate effective field theory describing universal properties of saturated gluons in hadron wavefunctions that are extracted from deeply inelastic scattering and hadron-hadron collision experiments at high energies.

hep-ph↗
arXiv2009

Long range two-particle rapidity correlations in A+A collisions from high energy QCD evolution

Long range rapidity correlations in A+A collisions are sensitive to strong color field dynamics at early times after the collision. These can be computed in a factorization formalism \cite{GelisLV5} which expresses the $n$-gluon inclusive spectrum at arbitrary rapidity separations in terms of the multi-parton correlations in the nuclear wavefunctions. This formalism includes all radiative and rescattering contributions, to leading accuracy in $α_sΔY$, where $ΔY$ is the rapidity separation between either one of the measured gluons and a projectile, or between the measured gluons themselves. In this paper, we use a mean field approximation for the evolution of the nuclear wavefunctions to obtain a compact result for inclusive two gluon correlations in terms of the unintegrated gluon distributions in the nuclear projectiles. The unintegrated gluon distributions satisfy the Balitsky-Kovchegov equation, which we solve with running coupling and with initial conditions constrained by existing data on electron-nucleus collisions. Our results are valid for arbitrary rapidity separations between measured gluons having transverse momenta $p_\perp,q_\perp\gtrsim \qs$, where $\qs$ is the saturation scale in the nuclear wavefunctions. We compare our results to data on long range rapidity correlations observed in the near-side ridge at RHIC and make predictions for similar long range rapidity correlations at the LHC.

hep-ph↗
arXiv2009

Multiparticle correlations in the Schwinger mechanism

We discuss the Schwinger mechanism in scalar QED and derive the multiplicity distribution of particles created under an external electric field using the LSZ reduction formula. Assuming that the electric field is spatially homogeneous, we find that the particles of different momenta are produced independently, and that the multiplicity distribution in one mode follows a Bose-Einstein distribution. We confirm the consistency of our results with an intuitive derivation by means of the Bogoliubov transformation on creation and annihilation operators. Finally we revisit a known solvable example of time-dependent electric fields to present exact and explicit expressions for demonstration.

hep-ph↗
arXiv2009

Glittering Glasmas

We compute the production of gluons from Glasma color flux tubes. We calculate the probability distribution of gluon multiplicities arising from the distribution of color electric and color magnetic flux tubes found in the Glasma. We show that the result corresponds to the negative binomial probability distribution observed in experiments. The parameter k that characterizes this distribution is proportional to the number of colors N_c^2-1 and to the number of flux tubes. For one gluon color and one flux tube, the multiplicity distribution is close to a Bose-Einstein distribution. We call this decay process "Glitter", a term that is explained below.

hep-ph↗