Early-times Yang-Mills dynamics and the characterization of strongly interacting matter with statistical learning

Fuente: arXiv
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Autores principales: Heffernan, Matthew R., Gale, Charles, Jeon, Sangyong, Paquet, Jean-François
Formato: Preprint
Publicado: 2023
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author Heffernan, Matthew R.
Gale, Charles
Jeon, Sangyong
Paquet, Jean-François
author_facet Heffernan, Matthew R.
Gale, Charles
Jeon, Sangyong
Paquet, Jean-François
contents In ultrarelativistic heavy-ion collisions, a plasma of deconfined quarks and gluons is formed within $1$ fm/c of the nuclei's impact. The complex dynamics of the collision before $\approx 1$ fm/c is often described with parametric models, which affect the predictivity of calculations. In this work, we perform a systematic analysis of LHC measurements from Pb-Pb collisions, by combining an \emph{ab-initio} model of the early stage of the collisions with a hydrodynamic model of the plasma. We obtain state-of-the-art constraints on the shear and bulk viscosity of quark-gluon plasma. We mitigate the additional cost of the ab-initio initial conditions by combining Bayesian model averaging with transfer learning, allowing us to account for important theoretical uncertainties in the hydrodynamics-to-hadron transition. We show that, despite the apparent strong constraints on the shear viscosity, metrics that balance the model's predictivity with its degree of agreement with data do not prefer a temperature-dependent specific shear viscosity over a constant value. We validate the model by comparing with discriminating observables not used in the calibration, finding excellent agreement.
format Preprint
id arxiv_https___arxiv_org_abs_2306_09619
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Early-times Yang-Mills dynamics and the characterization of strongly interacting matter with statistical learning
Heffernan, Matthew R.
Gale, Charles
Jeon, Sangyong
Paquet, Jean-François
Nuclear Theory
High Energy Physics - Phenomenology
Nuclear Experiment
In ultrarelativistic heavy-ion collisions, a plasma of deconfined quarks and gluons is formed within $1$ fm/c of the nuclei's impact. The complex dynamics of the collision before $\approx 1$ fm/c is often described with parametric models, which affect the predictivity of calculations. In this work, we perform a systematic analysis of LHC measurements from Pb-Pb collisions, by combining an \emph{ab-initio} model of the early stage of the collisions with a hydrodynamic model of the plasma. We obtain state-of-the-art constraints on the shear and bulk viscosity of quark-gluon plasma. We mitigate the additional cost of the ab-initio initial conditions by combining Bayesian model averaging with transfer learning, allowing us to account for important theoretical uncertainties in the hydrodynamics-to-hadron transition. We show that, despite the apparent strong constraints on the shear viscosity, metrics that balance the model's predictivity with its degree of agreement with data do not prefer a temperature-dependent specific shear viscosity over a constant value. We validate the model by comparing with discriminating observables not used in the calibration, finding excellent agreement.
title Early-times Yang-Mills dynamics and the characterization of strongly interacting matter with statistical learning
topic Nuclear Theory
High Energy Physics - Phenomenology
Nuclear Experiment
url https://arxiv.org/abs/2306.09619