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Nuclear Theory·nucl-th

Wednesday·May 20, 2026

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 05

    [Submitted on 18 May 2026] (cross-list from hep-ph)

    Looking at the Entropy in a Proton through a QGP Lens

    Dmitri E. Kharzeev🇺🇸 · Krishna Rajagopal🇺🇸

    We investigate the interplay between the thermodynamic (Gibbs) entropy of quark-gluon plasma (QGP) and the quantum entanglement entropy characteristic of confined hadronic states across the quark-hadron phase transition. In the deconfined regime, entropy is well described by the statistical mechanics of colored quarks and gluons. Upon hadronization, however, the macroscopic Gibbs entropy of the plasma cannot simply vanish; instead, it is reorganized into the configurational entropy of a gas of colorless hadrons together with quantum correlations among the confined partons within each hadron. We show that the entanglement entropy of the internal partonic wave functions inside hadrons provides a natural repository for this ``converted'' thermodynamic entropy, reconciling the apparent reduction of macroscopic entropy with the second law of thermodynamics. Either by extrapolating from known facts about deep inelastic scattering, or starting from model descriptions of the proton wave function, or starting from the Hagedorn spectrum of its resonances, we provide three estimates of the magnitude of the entanglement entropy carried by a proton, with very different uncertainties. All three estimates indicate that the internal entanglement entropy of the proton is similar in magnitude to the Gibbs entropy of the QGP droplet from which the proton formed as QGP cools through the quark-hadron transition, as for example throughout the universe microseconds after the Big Bang. These results suggest that entanglement entropy offers a bridge between the quantum information content of hadronic states and the thermodynamic entropy of the quark-gluon plasma, providing a new lens on the microscopic mechanism of confinement and the nature of the QCD phase transition.

    Comments:
    10 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2605.19058 [pdf]
    3 citations
  2. 06

    [Submitted on 19 May 2026] (cross-list from hep-ph)

    The stability of color-flavor-locked quark matter and massive CFL quark stars

    Wen-Li Yuan🇨🇳 · Bikai Gao🇯🇵

    Owing to the emergence of attractive interactions between quarks, color superconductivity is expected to occur, with the color-flavor-locked (CFL) phase favored at high densities. This work investigates the absolute stability of beta-equilibrated CFL quark matter in bulk within the modified Nambu-Jona-Lasinio model, under color and electric charge neutrality conditions relevant to compact stars. Motivated by the possible existence of an ultra-low-mass central compact object in the supernova remnant HESS J1731-347 and the "mass-gap" secondary component in the GW190814 event, we systematically explore how vector repulsion, attractive diquark pairing, and nonperturbative vacuum effects influence the stiffness of CFL quark matter and its stability. Our findings suggest the existence of a physically viable region of parameter space in which the CFL phase is the true ground state of strongly interacting matter, thereby theoretically supporting the scenario of self-bound quark stars. This configuration is not only consistent with current astrophysical constraints from NICER and LIGO/Virgo observations, but also provides a possible explanation for both the secondary component in GW190814 and the ultra-low-mass compact object with in HESS J1731-347.

    Comments:
    8 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2605.19657 [pdf]
    2 citations
  3. 07

    [Submitted on 19 May 2026] (cross-list from astro-ph.HE)

    Magnetized neutron stars: perturbative versus fully-numerical approaches

    Debarati Chatterjee🇮🇳 · Daw Guttmann🇫🇷 · Jérôme Novak🇫🇷 · Micaela Oertel🇫🇷 · Martin Jakob Steil🇩🇪

    (1) Background: for the study of highly magnetized neutron stars observed as magnetars, and to quantify the effect of this intense magnetic field onto the star's structure and shape which can be particularly relevant for the study of emission of continuous gravitational waves, both numerical and perturbative approaches have been developed. (2) Methods: we compare these two approaches in General Relativity with the limitation to the case where the magnetic field has a purely poloidal structure. The perturbative one (Konno-99) assumes that the deformation induced by the magnetic field is small and that this field arises only from dipole currents. The full numerical one is based on the library LORENE. (3) Results: we have used both approaches to compute the magnetic field distribution and the deformation of the star, varying the value of the magnetic field at the pole, the compactness of the star and its equation of state. (4) Conclusions: whereas the perturbative approach breaks down for very high polar magnetic field values (typically above a few times G), it gives very good results for observed values, even in magnetars. On the contrary, the numerical code exhibits resolution problems for relatively low magnetic field values (typically G), which translates into imprecise computation of the star's deformation and mass quadrupole moment.

    Comments:
    Contribution to special issue on "Magnetized Dense Matter in Compact Stars: From Fundamental Properties to Astrophysical Observables" in Universe
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2605.19761 [pdf]
    0 citations
  4. 08

    [Submitted on 19 May 2026] (cross-list from hep-ph)

    Lindblad-driven quarkonium production in heavy-ion collisions

    Néstor Armesto🇪🇸 · Miguel Ángel Escobedo🇪🇸 · Elena G. Ferreiro🇪🇸 · Víctor López-Pardo🇪🇸

    We study the production of the conventional quarkonium states in ultrarelativistic heavy-ion collisions using an open quantum system framework based on the Lindblad equation. Starting from the complex-valued in-medium potential, we derive the dissociation temperature and thermal decay width for each state, and compute their survival probabilities for a system undergoing Bjorken expansion. We then extend the framework to include recombination from thermalized charm and bottom quarks in the quark-gluon plasma, deriving a coalescence model for quarkonia from the Lindblad equation under the adiabatic approximation. The methodology provides a unified, first-principles-inspired description of suppression and recombination for both charmonium and bottomonium.

    Comments:
    9 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2605.19985 [pdf]
    4 citations
  5. 09

    [Submitted on 19 May 2026] (cross-list from hep-lat)

    Charmonium properties at high temperatures from lattice QCD

    Rasmus Normann Larsen🇩🇪 · Peter Petreczky🇺🇸 · Jorge Luis Dasilva Golan🇺🇸 · Johannes H. Weber🇩🇪

    We study charmonium properties at non-zero temperature in the temperature range 153 MeV 305 MeV using lattice QCD. We use HISQ action for dynamical quarks and Wilson clover action for valence charm quarks and calculate the correlation function of extended meson operators. Our lattice QCD results are consistent with the existence of all charmonium states below the open charm threshold in this temperature region. However, charmonium states acquire sizable thermal width, which increases with increasing temperature. The size of the thermal width follows the hierarchy of charmonium sizes, i.e. the smaller ground state charmonium has a smaller thermal width than the larger excited charmonia.

    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2605.20034 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE