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Nuclear Theory·nucl-th

Friday·February 2, 2018

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 05

    [Submitted on 6 Nov 2017] (cross-list from astro-ph.HE)

    A long-lived remnant neutron star after GW170817 inferred from its associated kilonova

    Yun-Wei Yu🇨🇳 · Liang-Duan Liu🇨🇳 · Zi-Gao Dai🇨🇳

    The successful joint observation of the gravitational wave event GW170817 and its multi-wavelength electromagnetic counterparts first enables human to witness a definite merger event of two neutron stars (NSs). This historical event confirms the origin of short-duration gamma-ray bursts (GRBs), and in particular, identifies the theoretically-predicted kilonova phenomenon that is powered by radioactive decays of -process heavy elements. However, whether a long-lived remnant NS could be formed during this merger event remains unknown, although such a central engine has been suggested by afterglow observations of some short-duration GRBs. By invoking this long-lived remnant NS, we here propose a model of hybrid energy sources for the kilonova AT2017gfo associated with GW 170817. While the early emission of AT2017gfo is still powered radioactively as usually suggested, its late emission is primarily caused by delayed energy injection from the remnant NS. In our model, only one single opacity is required and an intermediate value of is revealed, which could be naturally provided by lanthanide-rich ejecta that is deeply ionized by the emission from a wind of the NS. These self-consistent results indicate that a long-lived remnant NS, which must own a very stiff equation of state, had been formed during the merger event of GW170817. This provides a very stringent constraint on the strong interaction in nuclear-quark matter. It is further implied that such GW events could provide a probe of the early spin and magnetic evolutions of NSs, e.g., the burying of surface magnetic fields.

    Comments:
    10 pages, 4 figures. Following the referee's suggestions, the MCMC fitting method is described and the discussions on the EOS and magnetic field burying of the remnant NS are expanded. Accepted for publication in ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.01898 [pdf]
    ApJ(2018)·147 citations
  2. 06

    [Submitted on 31 Jan 2018] (cross-list from hep-ph)

    Polarization and dilepton angular distribution in pion-nucleon collisions

    Miklós Zétényi🇭🇺 · Enrico Speranza🇩🇪 · Bengt Friman🇩🇪

    We study hadronic polarization and the related anisotropy of the dilepton angular distribution for the reaction . We employ consistent effective interactions for baryon resonances up to spin-5/2 to compute their contribution to the anisotropy coefficient. We show that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We present results for the anisotropy coefficient including the and resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unraveling the resonance contributions to this process.

    Comments:
    Presented at the NSTAR2017 conference
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1802.00062 [pdf]
    Few Body Syst.(2018)·0 citations
  3. 07

    [Submitted on 1 Feb 2018] (cross-list from hep-ph)

    Direct photon production in relativistic heavy-ion collisions -- a theory update

    Charles Gale🇨🇦

    For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the "photon flow puzzle", and then focus on a recent development in the theory of photon emission from a non-equilibrium, strongly interacting medium.

    Comments:
    Talk given at the 12th International Workshop on High-pT Physics in the RHIC/LHC Era, 2-5 October, 2017, University of Bergen, Bergen, Norway
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1802.00128 [pdf]
    PoS(2019)·10 citations
  4. 08

    [Submitted on 1 Feb 2018] (cross-list from hep-ph)

    Quark mass functions and pion structure in the Covariant Spectator Theory

    E. P. Biernat🇵🇹 · F. Gross🇺🇸 · M. T. Peña🇵🇹 · A. Stadler🇵🇹 · S. Leitão🇵🇹

    The Covariant Spectator Theory is applied to the description of quarks and the pion. The dressed quark mass function is calculated dynamically in Minkowski space and used in the calculation of the pion electromagnetic form factor. The effects of the mass function on the pion form factor and the different quark-pole contributions to the triangle diagram are analyzed.

    Comments:
    7 pages, 5 figues, submitted to Few-Body Syst
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1802.00266 [pdf]
    Few Body Syst.(2018)·2 citations
  5. 09

    [Submitted on 1 Feb 2018] (cross-list from hep-ph)

    Multiparticle azimuthal cumulants in p+Pb collisions from a multiphase transport model

    Mao-Wu Nie🇨🇳 · Peng Huo🇺🇸 · Jiangyong Jia🇺🇸 · Guo-Liang Ma🇨🇳

    A new subevent cumulant method was recently developed, which can significantly reduce the non-flow contributions in long-range correlations for small systems compared to the standard cumulant method. In this work, we study multi-particle cumulants in +Pb collisions at TeV with a multiphase transport model (AMPT), including two- and four-particle cumulants ( and ) and symmetric cumulants [SC(2, 3) and SC(2, 4)]. Our numerical results show that is consistent with the experimental data, while the magnitude of is smaller than the experimental data, which may indicate either the collectivity is underestimated or some dynamical fluctuations are absent in the AMPT model. For the symmetric cumulants, we find that the results from the standard cumulant method are consistent with the experimental data, but those from the subevent cumulant method show different behaviors. The results indicate that the measurements from the standard cumulant method are contaminated by non-flow effects, especially when the number of produced particles is small. The subevent cumulant method is a better tool to explore the collectivity in small systems.

    Comments:
    15 pages, 6 figures; final published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1802.00374 [pdf]
    PRC(2018)·30 citations
  6. 10

    [Submitted on 1 Feb 2018] (cross-list from nucl-ex)

    Anisotropic flow: A case for Bottomonia

    Debasish Das (1) · Nirupam Dutta (2) ((1) SINP · (2) NISER)

    Studies of at RHIC and LHC energies have provided important elements towards the understanding on the production mechanisms and on the thermalization of charm quarks. Bottomonia has an advantage since it is a cleaner probe. A brief discussion has been provided for , which can become the new probe for QGP, including the necessity of studies for small systems.

    Comments:
    15 pages (This version is most updated)
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1802.00414 [pdf]
    Int.J.Mod.Phys.A(2018)·11 citations

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first authorsco-authorsvia INSPIRE