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Nuclear Theory·nucl-th

Thursday·July 25, 2024

15 papers—12 primary·3 cross-listed

All15Primary12Cross-lists3
  1. 13

    Covariant formulation of spinodal decomposition in rapidly expanding quark gluon plasma

    Joseph I. Kapusta🇺🇸 · Mayank Singh🇺🇸 · Thomas Welle🇺🇸

    Quantum Chromodynamics (QCD) is expected to have a first order phase transition between the confined hadron gas and the deconfined quark gluon plasma at high baryon densities. This will result in phase boundary effects in the metastable and unstable regions. It is important to include these effects in phenomenological models of heavy ion collisions to identify experimental signatures of a phase transition. This requires building intuition on phase separation in rapidly expanding fluids. In this work we present the covariant equations of relativistic hydrodynamics with a phase boundary, provide prescriptions to extend the equation of state to metastable and unstable regions, and show the effects of spinodal separation in a Bjorken flow.

    ↳ hep-phnucl-thPRC(2024)·7 citations
  2. 14

    Far-from-equilibrium attractors in kinetic theory for a mixture of quark and gluon fluids

    Ferdinando Frascà🇮🇹 · Andrea Beraudo🇮🇹 · Michael Strickland

    We exactly solve an RTA-Boltzmann equation that describes the dynamics of coupled massless quark and gluon fluids undergoing transversally homogeneous longitudinal boost-invariant expansion. We include a fugacity parameter that allows quarks to be out of chemical equilibrium and we account for the different collision rates of quarks and gluons, which are related by Casimir scaling. Based on these assumptions, we numerically determine the evolution of a large set of moments of the quark and gluon distribution functions and reconstruct their entire distribution functions. We find that both late and early-time attractors exist for all moments of the distribution functions containing more than one power of the squared longitudinal momentum. These attractors emerge long before the system reaches the regime where hydrodynamic approximations apply. In addition, we discuss how the shear viscous corrections and entropy density of the fluid mixture evolve and consider the properties of their respective attractors. Finally, the entropy production is also investigated for different initial values of momentum anisotropy and quark abundance.

    ↳ hep-phnucl-thNPA(2025)·10 citations
  3. 15

    A soft-hard framework with exact four momentum conservation for small systems

    I. Soudi🇺🇸 · W. Zhao🇺🇸 · A. Majumder🇺🇸 · C. Shen🇺🇸 · J. H. Putschke🇺🇸 · B. Boudreaux🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · Y. Chen🇺🇸 · R. Datta🇺🇸 · L. Du🇨🇦 and 41 other authors

    A new framework, called x-scape, for the combined study of both hard and soft transverse momentum sectors in high energy proton-proton (-) and proton-nucleus (-) collisions is set up. A dynamical initial state is set up using the 3d-Glauber model with transverse locations of hotspots within each incoming nucleon. A hard scattering that emanates from two colliding hotspots is carried out using the Pythia generator. Initial state radiation from the incoming hard partons is carried out in a new module called I-matter, which includes the longitudinal location of initial splits. The energy-momentum of both the initial hard partons and their associated beam remnants is removed from the hot spots, depleting the energy-momentum available for the formation of the bulk medium. Outgoing showers are simulated using the matter generator, and results are presented for both cases, allowing for and not allowing for energy loss. First comparisons between this hard-soft model and single inclusive hadron and jet data from - and minimum bias - collisions are presented. Single hadron spectra in - are used to carry out a limited (in number of parameters) Bayesian calibration of the model. Fair comparisons with data are indicative of the utility of this new framework. Theoretical studies of the correlation between jet and event activity at mid and forward rapidity are carried out.

    ↳ hep-phhep-exhep-thnucl-thPRC(2025)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE