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Nuclear Theory·nucl-th

Friday·November 1, 2024

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    [Submitted on 30 Oct 2024] (cross-list from astro-ph.HE)

    Direct nonparametric multimessenger constraints on the equation of state of cold dense nuclear matter

    Iuliu Cuceu🇬🇧 · Sandra Robles🇬🇧

    We utilize the now substantial amount of astrophysical observations of neutron stars (NSs), along with perturbative quantum chromodynamics (pQCD) calculations at high density, to directly constrain the NS equation of state (EOS). To this end, we construct nonparametric EOS priors by using Gaussian processes trained on 75 EOSs, which include models with either hadrons, hyperons, or quarks at high densities. We create a prior using the full EOS sample (model agnostic), and one prior for each EOS family to test model discrimination. We introduce a novel inference approach, which allows the simultaneous sampling of intrinsic and extrinsic parameters of binary NS mergers, as well as a nonparametric equation of state. We showcase this method in a Bayesian updating scheme by first performing a complete analysis of the binary NS merger event GW170817 with minimal assumptions, and sequentially adding information from x-ray and radio NS observations, along with pQCD calculations. Besides providing standard constraints, such as the pressure at twice nuclear saturation density , at confidence level, for the model agnostic prior, our methodology shows how the choice of EOS families used in conditioning changes the inferred astrophysical properties of the EOS, namely tidal deformability and maximum supported NS mass. We find hyperonic priors predicting higher tidal deformabilities for a NS, and hadronic priors being preferred by the considered astrophysical data.

    Comments:
    24 pages, 12 figures, 4 tables, 5 appendices. Discussion extended, matches published version
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2410.23407 [pdf]
    PRD(2025)·9 citations
  2. 05

    [Submitted on 31 Oct 2024] (cross-list from hep-ph)

    Hadronization in small and large systems

    Andrea Beraudo🇮🇹

    Recent results on particle production in hadronic collisions at the LHC, from proton-proton (pp) to nucleus-nucleus (AA), challenge the traditional paradigm of hadronization as a universal late-time process which can be factorized from the partonic description of the rest of the event. If the violation of this description in nuclear collisions has been accepted for long -- with several hadronic observables finding a natural interpretation assuming some form of recombination of partons from a deconfined medium -- this same occurrence came as a surprise in proton-proton collisions. Actually, strong indications that hadronization cannot be simply described by universal fragmentation fractions/functions were already found in fixed-target experiments, but limited to specific kinematic regions close to the beam rapidity, so that a complete change of paradigm did not look necessary. Here we show that a wide set of observables finds a natural interpretation assuming that in all high-energy hadronic collisions, from pp to AA, a deconfined medium is formed, acting as a reservoir in which a parton can undergo local color neutralization (LCN) through recombination with an opposite color charge. Hadronization, belonging to the non-perturbative domain of QCD, will always, inevitably, require some amount of educated modelling. However, some commong features to the various proposed model in the literature can be identified, which look necessary in order to describe the most recent data. Here we decide to focus on heavy-flavor (HF) production, since in this case the origin of at least one of the consituent quarks of the final hadron is well known and attributed to an initial hard partonic process.

    Comments:
    Contribution to the LHCP2024 Conference
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2410.23750 [pdf]
    PoS(2025)·2 citations
  3. 06

    [Submitted on 31 Oct 2024] (cross-list from hep-ph)

    Electric, Magnetic and Quadrupole Form Factors and Charge Radii of Vector Mesons: From Light to Heavy Sector in a Contact Interaction

    R. J. Hernández-Pinto🇲🇽 · L. X. Gutiérrez-Guerrero🇲🇽 · M. A. Bedolla🇲🇽 · A. Bashir🇲🇽

    We present a detailed survey of electric, magnetic and quadrupole form factors of light and heavy spin-1 vector mesons. It complements our analogous analysis of the electromagnetic form factors of pseudoscalar and scalar mesons reported earlier. Our formalism is based upon the Schwinger-Dyson equations treatment of a vector vector contact interaction and the Bethe-Salpeter equation description of relativistic two-body bound states. We compute the form factors, associated moments and charge radii, comparing these quantities to earlier theoretical studies and experimental results if and when possible. We also investigate the quark-mass dependence of the charge radii and find the anticipated hierarchy such that it decreases with increasing dressed quark masses. In addition, our analysis shows that the magnetic moment is independent of the mass of the light and heavy mesons. Our results agree with most measurements reported earlier, finding a negative quadrupole moment, implying the charge distribution is oblate.

    Comments:
    14 pages, 7 figures. arXiv admin note: text overlap with arXiv:2301.11881
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2410.23813 [pdf]
    PRD(2024)·24 citations
  4. 07

    [Submitted on 31 Oct 2024] (cross-list from hep-th)

    Mode analysis of Nambu-Goldstone modes in U(1) charged first-order relativistic viscous hydrodynamics

    Atsuhisa Ota🇨🇳

    We conduct a mode analysis of a general -charged first-order relativistic hydrodynamics within the framework of effective field theory for dissipative fluids in flat Minkowski spacetime. We derive the most general quadratic action for hydrodynamic modes, including stochastic noise, and analyze the corresponding dispersion relations in a consistent gradient expansion. We argue that spontaneous breaking of spacetime symmetry arises in the presence of a local thermal state specified by a local timelike four-vector. We demonstrate that hydrodynamical perturbations can be identified as Nambu-Goldstone (NG) modes, analogous to their embedding in global -invariant theories. We find that frame-invariant combinations of hydrodynamic transport coefficients determine the first-order dispersion relations in the low-energy limit, making the mode analysis manifestly independent of the choice of hydrodynamic frame. Assuming local Kubo-Martin-Schwinger (KMS) symmetry and unitarity of the underlying UV theory, we show that first-order hydrodynamics is stable if the enthalpy density is positive.

    Comments:
    49 pages, improvements in presentation
    Subjects:
    High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2410.23837 [pdf]
    PRD(2026)·4 citations
  5. 08

    [Submitted on 31 Oct 2024] (cross-list from hep-ph)

    A generalized picture of colour decoherence in dense QCD media

    Samuel Abreu🇨🇭 · Xoán Mayo López🇪🇸 · Guilherme Milhano🇵🇹 · Alba Soto-Ontoso🇪🇸

    We revisit the calculation of the soft gluon emission probability off a colour-singlet system that evolves in a quark-gluon plasma. The antenna is created in the presence of a medium and then emits a soft gluon outside. The gluon emission probability is modified with respect to the vacuum baseline due to interactions with the medium during the formation of the antenna and its propagation. Previous studies disregarded the former effect and found that the medium modification to the interference pattern of the antenna was controlled by the so-called critical angle , that exclusively depends on medium properties. We find that accounting for medium interactions during the antenna formation enhances the total rate of emissions off the antenna. Interestingly, it also promotes the notion of a critical angle to a dynamic quantity, denoted , that depends on both the medium and the antenna properties and is thus different for every splitting. As a consequence, depending on the region of parameter space, colour decoherence can either be delayed or accelerated with respect to previous estimates.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2410.24135 [pdf]
    JHEP(2025)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE