arXiv subjects

Aoumeur Daddi Hammou

Publications and source records attributed to Aoumeur Daddi Hammou.

4 recordsLinked to original sources

arXiv2026

From the universal Lindblad equation to Boltzmann equations: in-QGP quarkonium dynamics

Recently, a set of coupled singlet-octet universal Lindblad equations (ULEs) was derived within the framework of non-relativistic QCD (NRQCD) to describe quarkonium dynamics in the quark-gluon plasma (QGP). These equations provide a unified quantum description spanning the quantum Brownian and quantum optical regimes. In this work, we further develop this framework and establish its connection with semiclassical transport. We first derive the universal Lindblad equations within the potential non-relativistic QCD (pNRQCD) effective field theory and show that they coincide with the small-dipole limit of the NRQCD ULEs. We then derive the semiclassical limit of the NRQCD ULEs, obtaining a set of coupled singlet-octet Boltzmann equations. To our knowledge, this is the first derivation of Boltzmann transport equations directly from the universal Lindblad framework. The resulting equations are valid beyond the small-dipole approximation, allowing the evolution of heavy-quark pairs from compact to widely separated configurations. Taking their small-dipole limit allows a direct comparison with the Boltzmann equations of Yao et al. [Phys. Rev. D 99, 096028 (2019)], which were derived within pNRQCD from the Davies secular equation, relying on the rotating-wave approximation (RWA). While the singlet equations are found to be in near-complete agreement, the octet equation contains an additional collision term describing transitions within the continuum of octet scattering states, which is absent from the RWA-based derivation. Finally, we derive the leading quantum correction to the singlet Boltzmann equation. Our results establish a more general and systematic theoretical foundation for the semiclassical transport description of quarkonium in the QGP.

hep-ph↗

arXiv2026

General Lindblad equation for quarkonium evolution in a quark-gluon plasma

Accurate modelling and understanding of quarkonium production in ultrarelativistic heavy ion collisions requires a formalism that preserves the quantum properties of microscopic $\bar{Q}Q$ systems while treating the interaction of such pairs with the quark-gluon plasma (QGP). The open quantum system approach has recently emerged as one of the most fruitful schemes to meet such requirements. However, the quantum master equations obtained so far in this context are derived assuming a strict ordering between the QGP temperature $T$ and the $\bar{Q}Q$ energy gaps ($ΔE$) of the quarkonia bound states. This limits their predictive power since, as the QGP expands and cools down, the system traverse all regimes between the quantum Brownian motion (QBM) regime for $T\gtrsim ΔE$ to the quantum optical (QO) regime for $ΔE\gtrsim T$. In this paper, we derive and present a more general non-abelian quantum master equation of the Lindblad type, which does not suffer from these limitations and thus allows to faithfully describe the quantum evolution of the $Q\bar{Q}$ pairs during the whole QGP-evolution. We also provide some illustration of the key quantities governing this equation.

nucl-th↗

arXiv2025

Quarkonium dynamics in the quantum Brownian regime with non-abelian quantum master equations

Quarkonium production in ultrarelativistic heavy ions collisions is one of the best probes of the QGP formed in these collisions. Resorting to accurate methods to describe the $Q\bar{Q}$ evolution in a QGP is a prerequisite for the precise interpretation of experimental data. Among these methods, the quantum master equations (QME) derived within the formalism of open quantum systems are particularly relevant. We present exact numerical solutions in a 1D setting of previously derived quantum master equations (QME) in their quantum Brownian regime. Distinctive features of the in-medium bottomonia evolution with the QME are presented; some phenomenological consequences are addressed by considering evolutions for a fixed as well as EPOS4 temperature profiles. Next, we investigate the accuracy of the semiclassical approximation (often used to describe charmonium production in URHIC) by benchmarking the corresponding evolutions on the exact solutions derived with the QME for the case of a $c\bar{c}$ pair.

hep-ph↗

arXiv2023

Cosmic decoherence: primordial power spectra and non-Gaussianities

We study the effect of quantum decoherence on the inflationary cosmological perturbations. This process might imprint specific observational signatures revealing the quantum nature of the inflationary mechanism being related to the longstanding issue of the quantum-to-classical transition of inflationary fluctuations. Several works have investigated the effect of quantum decoherence on the statistical properties of primordial fluctuations. In particular, it has been shown that cosmic decoherence leads to corrections to the curvature power spectrum predicted by standard slow-roll inflation. Equally interesting, a non zero curvature trispectrum has been shown to be purely induced by cosmic decoherence, but surprisingly, decoherence seems not to generate any bispectrum. We further develop such an analysis by adopting a generalized form of the pointer observable, showing that decoherence does induce a non vanishing curvature bispectrum and providing a specific underlying concrete physical process. Present constraints on primordial bispectra allow to put an upper bound on the strength of the environment-system interaction. In full generality, the decoherence-induced bispectrum can be scale dependent provided one imposes the corresponding correction to the power spectrum to be scale independent. Such scale dependence on the largest cosmological scales might represent a distinctive imprint of the quantum decoherence process taking place during inflation. We also provide a criterion that allows to understand when cosmic decoherence induces scale independent corrections, independently of the type of environment considered. As a final result, we study the effect of cosmic decoherence on tensor perturbations and we derive the decoherence corrected tensor-to-scalar perturbation ratio. In specific cases, decoherence induces a blue tilted correction to the standard tensor power spectrum.

astro-ph.CO↗