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Nuclear Theory·nucl-th

Thursday·May 21, 2020

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    [Submitted on 19 May 2020] (cross-list from hep-ph)

    Medium modification of -jet fragmentation functions in Pb+Pb collisions at LHC

    Wei Chen🇨🇳 · Shanshan Cao🇺🇸 · Tan Luo🇪🇸 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳

    Coupled linear Boltzmann transport and hydrodynamic (CoLBT-hydro) model has been developed for simultaneous simulations of jet propagation and jet-induced medium excitation in heavy-ion collisions. Within this coupled approach, the final reconstructed jets in heavy-ion collisions include not only hadrons from the hadronization of medium modified jet shower partons from the linear Boltzmann transport (LBT) but also hadrons from the freeze-out of the jet-induced medium excitation in the hydrodynamic evolution of the bulk medium. Using the CoLBT-hydro model, we study medium modification of the fragmentation functions of -triggered jets in high-energy heavy-ion collisions at the Large Hadron Collider. The CoLBT-hydro model is shown to describe the experimental data not only on the suppression of leading hadrons within the jet cone at large momentum fraction relative to the transverse momentum of the trigger photon due to parton energy loss but also the enhancement of soft hadrons at small and due to jet-induced medium excitation. There is no suppression of the fragmentation function, however, at large momentum fraction relative to the transverse momentum of the reconstructed jet due to trigger bias and medium modification of quark to gluon jet fraction. For jets whose final transverse momenta are comparable to or larger than that of the trigger photon, the trigger bias can lead to enhancement of the jet fragmentation function at large .

    Comments:
    9 pages in RevTeX with 6 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2005.09678 [pdf]
    PLB(2020)·79 citations
  2. 07

    [Submitted on 19 May 2020] (cross-list from astro-ph.HE)

    Observational appearance of rapidly rotating neutron stars: X-ray bursts, cooling tail method, and radius determination

    Valery F. Suleimanov · Juri Poutanen · Klaus Werner

    Neutron stars (NSs) in low-mass X-ray binaries rotate at frequencies high enough to significantly deviate from sphericity ( 200--600 Hz). We investigate the effects of rapid rotation on the observational appearance of a NS. We propose analytical formulae relating gravitational mass and equatorial radius of the rapidly rotating NS to the mass and radius of a non-rotating NS of the same baryonic mass using accurate fully relativistic computations. We compute spectra from an oblate rotating NS observed at different inclination angles using the modified oblate Schwarzschild (MOS) approximation, where light bending is computed in Schwarzschild metric, but frame dragging and quadrupole moment of a NS are approximately accounted for in the photon redshift calculations. We generalize the cooling tail method to the case of a rapidly rotating NS to obtain the most probable values of and of the corresponding non-rotating NS with the same baryonic mass. We approximate the local spectra from the NS surface by a diluted blackbody using previously computed NS atmosphere models. We show that the NS radius could be overestimated by 3--3.5 km for face-on stars of km rotating at 700 Hz if the version of the cooling tail method for a non-rotating NS is used. We apply the method to an X-ray burst observed from the NS rotating at 532 Hz in SAX J1810.82609. The resulting radius of the non-rotating NS (assuming ) becomes km if it is viewed at inclination i=60 deg and km for a face-on view, which are smaller by 0.6 and 1.2 km than the radius obtained using standard cooling tail method ignoring rotation. The corresponding equatorial radii of these rapidly rotating NSs are 12.3 km (for i=60 deg) and 11.6\,km (for i=0 deg).

    Comments:
    17 pages, 16 figures, accepted for publication in Astronomy and Astrophysics
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    2005.09759 [pdf]
    Astron.Astrophys.(2020)·29 citations
  3. 08

    [Submitted on 20 May 2020] (cross-list from hep-ph)

    T-odd generalized and quasi transverse momentum dependent parton distribution in a scalar spectator model

    Xuan Luo🇨🇳 · Hao Sun🇨🇳

    Generalized transverse momentum dependent parton distributions (GTMDs), as mother funtions of transverse momentum dependent parton distributions (TMDs) and generalized parton distributions (GPDs), encode the most general parton structure of hadrons. We calculate four twist-two time reversal odd GTMDs of pion in a scalar spectator model. We study the dependence of GTMDs on the longitudinal momentum fraction carried by the active quark and the transverse momentum for different values of skewness defined as the longitudinal momentum transferred to the proton as well as the total momentum transferred to the proton. In addition, the quasi-TMDs and quasi-GPDs of pion have also been investigated in this paper.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2005.09832 [pdf]
    EPJC(2020)·18 citations
  4. 09

    [Submitted on 20 May 2020] (cross-list from nucl-ex)

    Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90

    K. B. Howard · U. Garg · M. Itoh · H. Akimune · M. Fujiwara · T. Furuno · Y. K. Gupta · M. N. Harakeh · K. Inaba · Y. Ishibashi · K. Karasudani · T. Kawabata and 11 other authors

    "Why are the tin isotopes soft?" has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, Zr and Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where--and how--the softness manifests itself between Zr and the cadmium and tin isotopes. The experiment was conducted using the Mo() reaction at MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with .

    Comments:
    Accepted for publication to Physics Letters B
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2005.10172 [pdf]
    PLB(2020)·24 citations
  5. 10

    [Submitted on 20 May 2020] (cross-list from hep-th)

    Revisiting relativistic magnetohydrodynamics from quantum electrodynamics

    Masaru Hongo🇺🇸 · Koichi Hattori🇯🇵

    We provide a statistical mechanical derivation of relativistic magnetohydrodynamics on the basis of the -dimensional quantum electrodynamics; the system endowed with the magnetic one-form symmetry. The conservation laws and the constitutive relations are presented in a manifestly covariant way with respect to the general coordinate transformation. The method of the local Gibbs ensemble (or nonequilibrium statistical operator) combined with the path-integral formula for the thermodynamic functional enables us to obtain an exact form of the constitutive relations. Applying the derivative expansion to the exact formula, we derive the first-order constitutive relations for the relativistic magnetohydrodynamics. The result for the QED plasma preserving the parity and charge-conjugation symmetries is equipped with two electrical resistivities and five (three bulk and two shear) viscosities. We also show that those transport coefficients satisfy the Onsager's reciprocal relation and a set of inequalities, indicating the semi-positivity of the entropy production rate consistent with the local second law of thermodynamics.

    Comments:
    47 pages, 4 figures, minor corrections, published version
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2005.10239 [pdf]
    JHEP(2021)·16 citations

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first authorsco-authorsvia INSPIRE