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Nuclear Theory·nucl-th

Monday·January 20, 2020

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 17 Jan 2020]

    Tidal Deformation of Neutron Stars from Microscopic Models of Nuclear Dynamics

    Andrea Sabatucci · Omar Benhar

    The observation of the gravitational wave signal GW170817, consistent with emission from the inspiral of a binary neutron-star system, provided information on the tidal deformation of the participating stars. The available data may be exploited to constrain the equation of state of densenuclear matter, as well as to shed light on the underlying models describing nuclear dynamics at microscopic level. In this paper we compare the experimental results to the predictions of different theoretical models, based on non relativistic nuclear many-body theory, the relativistic field-theoretical formalism, and a more phenomenological approach constrained by observed nuclear properties. While the precision of the available data does not allow to resolve the degeneracy of the models, our analysis shows a distinct sensitivity to the star compactness predicted by the different equations of state, which turns out to be significantly affected by relativistic boost corrections to the nucleon-nucleon potential.

    Comments:
    Accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); General Relativity and Quantum Cosmology (gr-qc)
    arXiv:
    2001.06294 [pdf]
    PRC(2020)·22 citations
  2. 02

    [Submitted on 15 Jan 2020]

    Systematic behavior of the fusion barrier parameters for heavy ion pairs [MSc Thesis]

    M. Ismail · A. Y. Ellithi · A. Adel · A. R. Abdulghany

    The nucleus-nucleus potential is calculated in the frame work of the double folding model (DFM) to obtain the Coulomb barrier parameters (barrier position and height), starting from M3Y-Reid nucleon-nucleon interaction and realistic nuclear matter distribution. The systematic behavior of the barrier parameters with mass numbers, charges, and radii of interacting nuclei is studied. The relation between the barrier height and radius is also discussed. The systematic behavior of the barrier parameters is presented in the form of simple analytical formulae, which can be used to calculate the barrier position and height directly, and show which factors can affect them. The potentials obtained from DFM are used to derive a universal function of the nuclear proximity potential which is useful for barrier calculations for heavy ion reactions. The obtained universal function reproduces the barrier parameters within less than 2% deviation from the values obtained using DFM for heavy and super heavy ion reactions. Reactions involving {\alpha}-particle are studied individually, and another form of the universal function is presented.

    Comments:
    Archived at the Central Library of Cairo University. Archiving information can be accessed via this link: http://lis.cl.cu.edu.eg/record=b1122408
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2001.06306 [pdf]
    0 citations
  3. 03

    [Submitted on 16 Jan 2020] (cross-list from astro-ph.HE)

    Gravitational waves or deconfined quarks: what causes the premature collapse of neutron stars born in short gamma-ray bursts?

    Nikhil Sarin · Paul D. Lasky · Gregory Ashton

    We infer the collapse times of long-lived neutron stars into black holes using the X-ray afterglows of 18 short gamma-ray bursts. We then apply hierarchical inference to infer properties of the neutron star equation of state and dominant spin-down mechanism. We measure the maximum non-rotating neutron star mass and constrain the fraction of remnants spinning down predominantly through gravitational-wave emission to with uncertainties. In principle, this method can determine the difference between hadronic and quark equation of states. In practice, however, the data is not yet informative with indications that these neutron stars do not have hadronic equation of states at the level. These inferences all depend on the underlying progenitor mass distribution for short gamma-ray bursts produced by binary neutron star mergers. The recently announced gravitational-wave detection of GW190425 suggests this underlying distribution is different from the locally-measured population of double neutron stars. We show that and constraints depend on the fraction of binary mergers that form through a distribution consistent with the locally-measured population and a distribution that can explain GW190425. The more binaries that form from the latter distribution, the larger needs to be to satisfy the X-ray observations. Our measurements above are marginalised over this unknown fraction. If instead, we assume GW190425 is not a binary neutron star merger, i.e the underlying mass distribution of double neutron stars is the same as observed locally, we measure .

    Comments:
    Published in Phys. Rev. D: Vol 101, Issue 6
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2001.06102 [pdf]
    PRD(2020)·57 citations
  4. 04

    [Submitted on 15 Jan 2020] (cross-list from hep-ph)

    QCD parameters and from heavy quark sum rules

    Stephan Narison (LUPM-CNRS, Montpellier-FR)🇫🇷

    We report results of our recent works [1,2] where we where the correlations between the c,b-quark running masses{m}_{c,b}, the gluon condensate<\alpha_s G^2> and the QCD coupling \alpha_s in the MS-scheme from an analysis of the charmonium and bottomium spectra and the B_c-meson mass. We use optimized ratios of relativistic Laplace sum rules (LSR) evaluated at the \mu-subtraction stability point where higher orders PT and D< 6-8-dimensions non-perturbative condensates corrections are included. We obtain [1] \alpha_s(2.85)=0.262(9) and \alpha_s(9.50)=0.180(8) from the (pseudo)scalar M_{\chi_{0c(0b)}}-M_{\eta_{c(b)}} mass-splittings at \mu=2.85(9.50) GeV. The most precise result from the charm channel leads to \alpha_s(M_\tau)=0.318(15) and \alpha_s(M_Z)=0.1183(19)(3) in excellent agreement with the world average: \alpha_s(M_Z)=0.1181(11)[3,4]. Updated results from a global fit of the (axial-)vector and (pseudo)scalar channels using Laplace and Moments sum rules @ N2LO [1] combined with the one from M_{B_c} [2] lead to the new tentative QCD spectral sum rules (QSSR) average : m_c(m_c)|_average= 1266(6) MeV and m_b(m_b)|_average=4196(8) MeV. The values of the gluon condensate <\alpha_s G^2> from the (axial)-vector charmonium channels combined with previous determinations in Table 1, leads to the new QSSR average [1]: <\alpha_s G^2>_average=(6.35\pm 0.35)x 10^{-2} GeV^4. Our results clarify the (apparent) discrepancies between different estimates of <\alpha_s G^2> from J/\psi sum rule but also shows the sensitivity of the sum rules on the choice of the \mu-subtraction scale. As a biproduct, we deduce the B_c-decay constants f_{B_c}=371(17) MeV and f_{B_c}(2S)< 139(6) MeV.

    Comments:
    Review talk presented at QCD19 (2-7 july 2019, Montpellier - FR) and at HEPMAD19 (14-20 october 2019, Antananarivo-MG). 13 pages, 1 Table. To appear in Nucl. Phys. Proceedings (2020): Reference corrected. arXiv admin note: substantial text overlap with arXiv:1801.00592
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2001.06346 [pdf]
    Nucl.Part.Phys.Proc.(2020)·6 citations
  5. 05

    [Submitted on 17 Jan 2020] (cross-list from hep-ph)

    Chiral effective Lagrangian for heavy-light mesons from QCD

    Qing-Sen Chen🇨🇳 · Hui-Feng Fu🇨🇳 · Yong-Liang Ma🇨🇳 · Qing Wang🇨🇳

    We derive the chiral effective Lagrangian for heavy-light mesons in the heavy quark limit from QCD under proper approximations. The low energy constants in the effective Lagrangian are expressed in terms of the light quark self-energy. With typical forms of the running coupling constant of QCD and the quark self-energy obtained from Dyson-Schwinger equations as well as lattice QCD, we estimate the low energy constants in the model and the strong decay widths. A comparison with data and some discussions of the numerical results are presented.

    Comments:
    Published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2001.06418 [pdf]
    PRD(2020)·4 citations
  6. 06

    [Submitted on 17 Jan 2020] (cross-list from nucl-ex)

    Beam energy dependence of net- fluctuations measured by the STAR experiment at RHIC

    STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 · E. C. Aschenauer🇺🇸 · M. U. Ashraf🇨🇳 and 346 other authors

    The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the Quantum Chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. We report the measurement of efficiency and centrality bin width corrected cumulant ratios (, ) of net- distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality and rapidity. The results are for Au + Au collisions at five beam energies ( = 19.6, 27, 39, 62.4 and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to Ultra-relativistic Quantum Molecular Dynamics (UrQMD) and Hadron Resonance Gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon and net-charge data, indicate freeze-out conditions similar to those of kaons. However, large deviations are found when comparing to temperatures obtained from net-proton fluctuations. The net- cumulants show a weak, but finite, dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.

    Comments:
    12 pages, 9 figures, 3 tables, submitted to Phys.Rev.C
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2001.06419 [pdf]
    PRC(2020)·32 citations
  7. 07

    [Submitted on 17 Jan 2020] (cross-list from hep-ph)

    On gauge invariance of transverse momentum dependent distributions at small x

    Renaud Boussarie🇺🇸 · Yacine Mehtar-Tani🇺🇸

    The interplay between the small x limit of QCD amplitudes and QCD factorization at moderate x has been studied extensively in recent years. It was finally shown that semiclassical formulations of small x physics can have the form of an infinite twist framework involving Transverse Momentum Dependent (TMD) distributions in the eikonal limit. In this work, we demonstrate that small x distributions can be formulated in terms of transverse gauge links. This allows in particular for direct and efficient decompositions of observables into subamplitudes involving gauge invariant sub-operators which span parton distributions.

    Comments:
    21 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2001.06449 [pdf]
    PRD(2021)·38 citations

Affiliations

first authorsco-authorsvia INSPIRE