arXiv subjects

Gabriel Rabelo-Soares

Publications and source records attributed to Gabriel Rabelo-Soares.

4 recordsLinked to original sources

arXiv2026

Hydrodynamical Initial State in Small Systems From the Phase-Space Entropy

The experimental observation of collective behavior in proton-proton and proton-nucleus collisions poses a fundamental theoretical question regarding the proper characterization of the initial state underlying hydrodynamic evolution. While relativistic hydrodynamics requires an initial condition characterized by an entropy current, corresponding to a maximally mixed state, the microscopic description of the proton is based on inherently quantum objects that probes projections of pure states. We show that the appropriate matching between hadronic structure and classical hydrodynamics emerges from the coarse-graining of the partonic Wigner distribution, leading naturally to a Husimi distribution and its associated Wehrl entropy. This entropy provides a semiclassical, positive-definite measure of the density of accessible microstates at a given resolution scale, and therefore constitutes the appropriate quantity to characterize entropy deposition in small collision systems.

hep-ph↗

arXiv2026

QCD Wehrl and entanglement entropies in a gluon spectator model at small-$x$

Recent studies have shown that hadronic multiplicity in deep inelastic scattering can be associated with entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase-space structure of the proton. In this work, we investigate the proton Wehrl entropy constructed from the gluon Husimi distribution, which provides a positive phase-space description within the present definitions and model calculations. Within this framework, we employ a gluon light-front spectator model based on soft-wall AdS/QCD-inspired wave functions, with free parameters constrained by global NNPDF fits, allowing us to compute both parton distribution functions and Wigner distributions. The Husimi distribution is obtained via Gaussian smearing of the Wigner distribution with width given by the saturation scale in the GBW model. We show that from a normalized Husimi distribution one can decompose the Wehrl entropy into an entanglement entropy term and a residual term associated with transverse degrees of freedom. Numerical results for the proton entanglement entropy are shown and compared with CMS data, while the Wehrl entropy is presented for different values of the virtuality.

hep-ph↗

arXiv2026

Hydrodynamic Initial Conditions in Small Systems from Proton Phase-Space Entropy

The experimental observation of collective behaviour in proton-proton and proton-nucleus collisions poses a fundamental theoretical question regarding the proper characterization of the initial state underlying hydrodynamic evolution. While relativistic hydrodynamics requires an initial condition (IC) characterized by an entropy current, corresponding to a maximally mixed state, the microscopic description of the proton is based on inherently quantum objects, that are projections of pure states. We show that the appropriate matching between proton wave function and classical hydrodynamics emerges from the coarse-graining of its phase-space distribution quantified by the Wehrl-like entropy. This entropy provides a semi-classical, positive-definite measure of the density of accessible microstates at a given resolution scale, and therefore constitutes the appropriate quantity to characterize entropy deposition in small collision systems.

hep-ph↗

arXiv2026

Muon trident process at far-forward LHC detectors

The electromagnetic production of a dilepton pair in the muon - ion scattering, usually denoted muon trident process, is investigated considering the feasibility of studying processes induced by muons at LHC using its far-forward detectors. The total and differential cross - sections are estimated taking into account of the Bethe-Heitler and bremsstrahlung channels, and predictions for the event rates expected for muon - tungsten ($μW$) collisions at the LHC energies are presented. Our results indicate that the observation of the muon trident process is feasible at FASER$ν$. In particular, our results indicate that the electromagnetic production of $τ^+ τ^-$ pairs in the $μW$ scattering can, in principle, be observed for the first time ever at the LHC. In addition, we present our predictions for the production of QED bound states. Finally, results for the trident process at the FASER$ν$2 detector are also presented.

hep-ph↗