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Nuclear Theory·nucl-th

Friday·July 15, 2022

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 14 Jul 2022]

    Trace anomaly as signature of conformality in neutron stars

    Yuki Fujimoto🇺🇸 · Kenji Fukushima🇯🇵 · Larry D. McLerran🇺🇸 · Michal Praszalowicz🇵🇱

    We discuss an interpretation that a peak in the sound velocity in neutron star matter, as suggested by the observational data, signifies strongly-coupled conformal matter. The normalized trace anomaly is a dimensionless measure of conformality leading to the derivative and the non-derivative contributions to the sound velocity. We find that the peak in the sound velocity is attributed to the derivative contribution from the trace anomaly that steeply approaches the conformal limit. Smooth continuity to the behavior of high-density QCD implies that the matter part of the trace anomaly may be positive definite. We discuss a possible implication of the positivity condition of the trace anomaly on the - relation of the neutron stars.

    Comments:
    6 pages, 3 figures; accepted in PRL
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2207.06753 [pdf]
    PRL(2022)·183 citations
  2. 02

    [Submitted on 14 Jul 2022]

    Dynamical Pair Production at Sub-Barrier Energies for Light Nuclei

    T. Settlemyre · H. Zheng · A. Bonasera

    In the collision of two heavy ions, the strong repulsion coming from the Coulomb field is enough to produce pair(s) from vacuum fluctuations. The energy is provided by the kinetic energy of the ions and the Coulomb interaction at the production point. If, for instance, the electron is located at the center of mass (C.M.) of the two ions moving along the \emph{z}-axis, and the positron is at a distance \emph{x} from the electron, the ions can be accelerated towards each other since the Coulomb barrier is lowered by the presence of the electron. This screening results in an increase in the kinetic energy of the colliding ions and may result in an increase in the fusion probability of light ions above the adiabatic limit.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2207.06900 [pdf]
    Particles(2022)·3 citations
  3. 03

    [Submitted on 12 Jul 2022] (cross-list from hep-ph)

    Systematics of fully heavy dibaryons

    Xin-Zhen Weng🇮🇱 · Shi-Lin Zhu🇨🇳

    We systematically study the mass spectra of the fully heavy dibaryons in an extended chromomagnetic model, which includes both the colorelectric and chromomagnetic interactions. We find no stable state below the corresponding baryon-baryon thresholds. Besides the masses, we also estimate the relative width ratios of the two-body decay channels. We hope our study will be of help for future experiments.

    Comments:
    19 pages, 1 figure
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2207.05505 [pdf]
    EPJC(2024)·16 citations
  4. 04

    [Submitted on 13 Jul 2022] (cross-list from hep-ph)

    Pseudo-scalar mesons: light front wave functions, GPDs and PDFs

    L. Albino🇲🇽 · I. M. Higuera-Angulo🇲🇽 · K. Raya🇪🇸 · A. Bashir🇲🇽

    We develop a unified algebraic model which satisfactorily describes the internal structure of pion and kaon as well as heavy quarkonia ( and ). For each of these mesons, we compute their generalized parton distributions (GPDs), built through the overlap representation of their light-front wave function, tightly constrained by the modern and precise knowledge of their quark distribution amplitudes. From this three-dimensional knowledge of mesons, we deduce parton distribution functions (PDFs) as well as electromagnetic form factors and construct the impact parameter space GPDs. The PDFs for mesons formed with light quarks are then evolved from the hadronic scale of around 0.3 GeV to 5.2 GeV, probed in experiments. We make explicit comparisons with experimental results available and with earlier theoretical predictions.

    Comments:
    15 pages, 10 figures. Accepted in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2207.06550 [pdf]
    PRD(2022)·33 citations
  5. 05

    [Submitted on 14 Jul 2022] (cross-list from nucl-ex)

    Measurement of sequential suppression in Au+Au collisions at = 200 GeV with the STAR experiment

    STAR Collaboration: B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · D. M. Anderson · E. C. Aschenauer · J. Atchison · V. Bairathi · W. Baker and 361 other authors

    We report on measurements of sequential suppression in Au+Au collisions at = 200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0-60% centrality class, the nuclear modification factors (), which quantify the level of yield suppression in heavy-ion collisions compared to + collisions, for (1S) and (2S) are and , respectively, while the upper limit of the (3S) is 0.17 at a 95% confidence level. This provides experimental evidence that the (3S) is significantly more suppressed than the (1S) at RHIC. The level of suppression for (1S) is comparable to that observed at the much higher collision energy at the Large Hadron Collider. These results point to the creation of a medium at RHIC whose temperature is sufficiently high to strongly suppress excited states.

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2207.06568 [pdf]
    PRL(2023)·51 citations
  6. 06

    [Submitted on 14 Jul 2022] (cross-list from nucl-ex)

    Isoscalar Giant Resonances: Experimental Studies

    Umesh Garg

    Giant resonances--highly collective, high-frequency oscillations of the atomic nucleus--are the focus of this chapter. We discuss the isoscalar excitations, where the protons and neutrons oscillate in phase, up to angular-momentum transfers = 3. The procedures of experiments and data analysis employed in extracting the strength distributions associated with these resonances are discussed. The experimentally extracted strength distributions are presented, along with information on the properties of these resonances available to date. The effect of deformation of the nuclear ground state on the resonance strength distributions is discussed. Furthermore, the exciting opportunities being opened with the current and future availability of rare isotope beams the world over are expounded.

    Comments:
    Contribution to the "Handbook of Nuclear Physics", Springer, 2023, I. Tanihata, H. Toki and T. Kajino, Eds. arXiv admin note: substantial text overlap with arXiv:1801.03672
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2207.06785 [pdf]
    2 citations
  7. 07

    [Submitted on 14 Jul 2022] (cross-list from hep-ph)

    Condensed dark matter with a Yukawa interaction

    Raghuveer Garani🇮🇹 · Michel H.G. Tytgat🇧🇪 · Jérôme Vandecasteele🇩🇪

    We explore the possible phases of a condensed dark matter (DM) candidate taken to be in the form of a fermion with a Yukawa coupling to a scalar particle, at zero temperature but at finite density. This theory essentially depends on only four parameters, the Yukawa coupling, the fermion mass, the scalar mediator mass, and the DM density. At low fermion densities we delimit the Bardeen-Cooper-Schrieffer (BCS), Bose-Einstein Condensate (BEC) and crossover phases as a function of model parameters using the notion of scattering length. We further study the BCS phase by consistently including emergent effects such as the scalar density condensate and superfluid gaps. Within the mean field approximation, we derive the consistent set of gap equations, retaining their momentum dependence, and valid in both the non-relativistic and relativistic regimes. We present numerical solutions to the set of gap equations, in particular when the mediator mass is smaller and larger than the DM mass. Finally, we discuss the equation of state (EoS) and possible astrophysical implications for asymmetric DM.

    Comments:
    10+19 pages, 6+8 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2207.06928 [pdf]
    PRD(2022)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE