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Nuclear Theory·nucl-th

Monday·December 11, 2023

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 7 Dec 2023]

    Ultracentral heavy ion collisions, transverse momentum and the equation of state

    Govert Nijs🇨🇭 · Wilke van der Schee🇨🇭

    Ultracentral heavy ion collisions due to their exceptionally large multiplicity probe an interesting regime of quark-gluon plasma where the size is (mostly) fixed and fluctuations in the initial condition dominate. Spurred by the recent measurement of the CMS collaboration we investigate the driving factors of the increase of transverse momentum, including a complete analysis of the influence of the QCD equation of state. Particularly interesting is the influence of the centrality selection as well as the initial energy deposition.

    Comments:
    4 pages, 5 figures and an appendix. The Trajectum code can be found at https://sites.google.com/view/govertnijs/trajectum and plotting routines can be found at http://wilkevanderschee.nl/trajectum
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2312.04623 [pdf]
    PLB(2024)·25 citations
  2. 02

    [Submitted on 8 Dec 2023]

    Far-off-equilibrium early-stage dynamics in high-energy nuclear collisions

    Chandrodoy Chattopadhyay🇺🇸 · Ulrich Heinz🇺🇸 · Thomas Schaefer🇺🇸

    We explore the far-off-equilibrium aspects of the (1+1)-dimensional early-stage evolution of a weakly-coupled quark-gluon plasma using kinetic theory and hydrodynamics. For a large set of far-off-equilibrium initial conditions the system exhibits a peculiar phenomenon where its total equilibrium entropy decreases with time. Using a non-equilibrium definition of entropy based on Boltzmann's H-function, we demonstrate how this apparently anomalous behavior is consistent with the second law of thermodynamics. We also use the H-function to formulate `maximum-entropy' hydrodynamics, a far-off-equilibrium macroscopic theory that can describe both free-streaming and near-equilibrium regimes of quark-gluon plasma in a single framework.

    Comments:
    Contribution to Quark Matter 2023 (4 pages, 4 figures)
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2312.04760 [pdf]
    EPJ Web Conf.(2024)·1 citation
  3. 03

    [Submitted on 8 Dec 2023]

    Understanding oscillating features of the timelike nucleon electromagnetic form factors within the extending vector meson dominance model

    Bing Yan🇨🇳 · Cheng Chen🇨🇳 · Xia Li🇨🇳 · Ju-Jun Xie🇨🇳

    We investigate the nonmonotonic behavior observed in the time-like nucleon electromagnetic form factors. Using a phenomenological extending vector meson dominance model, where the ground states and and their excited states , , and are taken into account, we have successfully reproduced the cross sections of and reactions. Furthermore, we have derived the nucleon electromagnetic form factors in the time-like region, and it is found that the so-called periodic behaviour of the nucleon effective form factors is not confirmed. However, there are indeed nonmonotonic structures in the line shape of nucleon effective form factors, which can be naturally reproduced by considering the contributions from the low-lying excited vector states.

    Comments:
    Published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2312.04866 [pdf]
    PRD(2024)·12 citations
  4. 04

    [Submitted on 8 Dec 2023]

    Improved description of nuclear charge radii: Global trends beyond shell closure

    Rong An · Xiang Jiang · Na Tang · Li-Gang Cao · Feng-Shou Zhang

    Charge radii measured with high accuracy provide a stringent benchmark for characterizing nuclear structure phenomena. In this work, the systematic evolution of charge radii for nuclei with - is investigated through relativistic mean field theory with effective forces NL3, PK1, and NL3. The neutron-proton () correlation around Fermi surface originated from the unpaired neutron and proton has been taken into account tentatively in order to reduce the overestimated odd-even staggering of charge radii. This improved method can give an available description of charge radii across shell closure. A remarkable observation is that the charge radii beyond shell closure follow the similarly steep increasing trend, namely irrespective of the number of protons in the nucleus. Especially, the latest results of charge radii for nickel and copper isotopes can be reproduced remarkably well. Along isotonic chain, the sudden increase of charge radii is weakened across , but presented evidently across closed shell. The abrupt changes of charge radii across are also shown along and isotones, but the latter with a less slope. This seems to provide a sensitive indicator to identify the new magicity of a nucleus with universal trend of charge radii.

    Comments:
    13 pages, 4 figures,
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2312.04912 [pdf]
    PRC(2024)·17 citations
  5. 05

    [Submitted on 8 Dec 2023]

    Role of initial transverse momentum in a hybrid approach

    Niklas Götz🇩🇪 · Lucas Constantin🇩🇪 · Hannah Elfner🇩🇪

    The purpose of this work is to study the effect of exchanging initial condition models in a modular hybrid approach. The focus lies on the event-by-event correlations of elliptic and triangular flow. This study is performed in the hybrid approach SMASH-vHLLE, composed of the hadronic transport approach SMASH and the (3+1)d viscous hydrodynamic code vHLLE. The initial condition models investigated are SMASH IC, Trento and IP-Glasma. Correlations are calculated on an event-by-event basis between the eccentricities and momentum anisotropies of the initial state as well as the momentum anisotropies in the final state, both for ultra-central and off-central collisions for AuAu collisions at GeV. This work demonstrates that, although averaged values for the eccentricities of these models are very similar, substantial differences exist both in the distributions of eccentricities, the correlations amongst the initial state properties as well as in the correlations between initial state and final state properties. Notably, whereas initial state momentum anisotropy is shown to not affect the final state flow, the presence of radial flow affects the emergence of final state momentum anisotropies. Inclusion of radial flow in the linear fit improves the prediction of final state flow from initial state properties. The presence of momentum in the initial state has an effect on the emergence of flow and is therefore a relevant part of initial state models, challenging the common understanding of final state momentum anisotropies being a linear response to initial state eccentricity only.

    Comments:
    17 pages, 12 figures. Raw data of figures is provided in the supplemental material
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2312.05001 [pdf]
    PRC(2024)·5 citations
  6. 06

    [Submitted on 8 Dec 2023]

    Feasibility of perturbative generation of bound-states from resonances or virtual states

    C.-J. Yang🇷🇴

    I investigate whether it is possible to generate bound-states from resonances or virtual states through first-order perturbation theory. Using contact-type potentials as those appeared in pionless effective field theory, I show that it is possible to obtain negative-energy states by sandwiching a next-to-leading order (NLO) interaction with the leading-order (LO) wavefunctions, under the presence of LO resonances or virtual states. However, at least under the framework of time-independent Schrödinger equation and Hermitian Hamiltonian, there is an inability to create bound-states with structure similar to those formed by the non-perturbative treatments.

    Comments:
    17 pages, 14 figures. Published version with an appendix added and the title changed
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2312.05085 [pdf]
    PRC(2024)·5 citations
  7. 07

    [Submitted on 8 Dec 2023]

    Relativistic Faddeev 3D Equations for Three-Body Bound States Without Two-Body Matrices

    M. Mohammadzadeh · M. Radin · M. R. Hadizadeh

    This paper explores a novel revision of the Faddeev equation for three-body (3B) bound states, as initially proposed in Ref. \cite{golak2013three}. This innovative approach, referred to as \tmatrixfree in this paper, directly incorporates two-body (2B) interactions and completely avoids the 2B transition matrices. We extend this formalism to relativistic 3B bound states using a three-dimensional (3D) approach without using partial wave decomposition. To validate the proposed formulation, we perform a numerical study using spin-independent Malfliet-Tjon and Yamaguchi interactions. Our results demonstrate that the relativistic \tmatrixfree Faddeev equation, which directly implements boosted interactions, accurately reproduces the 3B mass eigenvalues obtained from the conventional form of Faddeev equation, referred to as \tmatrixdependent in this paper, with boosted 2B matrices. Moreover, the proposed formulation provides a simpler alternative to the standard approach, avoiding the computational complexity of calculating boosted 2B matrices and leading to significant computational time savings.

    Subjects:
    Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2312.05132 [pdf]
    PTEP(2024)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE