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Nuclear Theory·nucl-th

Monday·December 3, 2018

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 29 Nov 2018]

    Quarkyonic Matter and Neutron Stars

    Larry McLerran🇺🇸 · Sanjay Reddy🇺🇸

    We consider Quarkyonic Matter to naturally explain the observed properties of neutron stars. We argue that such matter might exist at densities close to that of nuclear matter and at the onset, the pressure and the sound velocity in Quarkyonic matter increase rapidly. In the limit of large number of quark colors , this transition is characterized by a discontinuous change in pressure as a function of baryon number density. We make a simple model of Quarkyonic matter and show that generically the sound velocity is a non-monotonic function of density -- it reaches a maximum at relatively low density, decreases, and then increases again to its asymptotic value of .

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1811.12503 [pdf]
    PRL(2019)·397 citations
  2. 02

    [Submitted on 30 Nov 2018]

    Light vector mesons (, and ) in strong magnetic fields: A QCD sum rule approach

    Amruta Mishra🇮🇳 · Ankit Kumar🇮🇳 · Pallabi Parui🇮🇳 · Sourodeep De🇮🇳

    The mass modifications of the light vector mesons (, and ) are investigated in asymmetric nuclear matter in the presence of strong magnetic fields, using a QCD sum rule approach. These are computed from the medium modifications of the non-strange and strange light quark condensates as well as scalar gluon condensate. The quark and gluon condensates are calculated from the medium changes of the scalar fields (non-strange and strange) and a scalar dilaton field in the magnetized nuclear matter, within a chiral SU(3) model. The scalar dilaton field within the model breaks the scale invariance of QCD and simulates the gluon condensate. The anomalous magnetic moments for the nucleons are taken into account in the present study.

    Comments:
    23 pages, 6 figures, to be published in Phys.Rev.C. arXiv admin note: text overlap with arXiv:1405.3508
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1811.12570 [pdf]
    PRC(2019)·17 citations
  3. 03

    [Submitted on 29 Nov 2018] (cross-list from hep-ph)

    First results on the scalar WIMP-pion coupling, using the XENON1T experiment

    E. Aprile🇺🇸 · J. Aalbers🇸🇪 · F. Agostini🇮🇹 · M. Alfonsi🇩🇪 · L. Althueser🇩🇪 · F. D. Amaro🇵🇹 · M. Anthony🇺🇸 · V. C. Antochi🇸🇪 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 · B. Bauermeister🇸🇪 · M. L. Benabderrahmane🇦🇪 and 120 other authors

    We present first results on the scalar WIMP-pion coupling from 1 tyr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most non-relativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons, and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of cm (90 % confidence level) at 30 GeV/c WIMP mass.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1811.12482 [pdf]
    PRL(2019)·53 citations
  4. 04

    [Submitted on 29 Nov 2018] (cross-list from hep-ph)

    Multicomponent Superfluids and Superconductors in Dense Nuclear and Quark Matter

    Alexander Haber🇦🇹

    Matter at intermediate baryon densities and low temperatures is notoriously hard to tackle theoretically. Whereas lattice methods cannot cover more than rather small densities, perturbative methods are only applicable at much higher densities. The regime of intermediate chemical potential at low temperatures in the QCD-phase diagram is therefore out of reach of first-principle methods, thus we have to rely on stellar objects to investigate dense nuclear and quark matter at low temperatures. Compact stars can serve as an unique laboratory for this regime. Due to their fast rotation and high magnetic field, phenomena like hydrodynamic instabilities and the formation of vortices/flux tubes become of phenomenological interest. In my thesis, I investigate these multicomponent systems in a consistent multi-fluid treatment. By starting from a fieldtheoretical, bosonic model, the phase structure of a two-fluid system, e.g. consisting of superfluid neutrons and superconducting protons, is explored. Consequently, hydrodynamic instabilities, which might serve as trigger for pulsar glitches, are calculated for these two-fluid systems. By incorporating a gauge field and taking into account the charge of one scalar field, the influence of a superfluid on the magnetic phase structure of a superconductor is studied. In the last part, color superconducting quark matter, which can effectively be described as a multicomponent (color-)supercondcutor, is investigated.

    Comments:
    Phd thesis based on: PRD 93 no.2 (2016) 025011 (arXiv:1510.01982), EPJ Web Conf. 137 (2017) 09003 (arXiv:1612.01865), PRD 95 no.11 (2017) 116016 (arXiv:1704.01575) and J.Phys.G45 no.6 (2018) 065001 (arxiv:1712.08587)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.12533 [pdf]
    2 citations
  5. 05

    [Submitted on 30 Nov 2018] (cross-list from nucl-ex)

    Determination of hexadecapole () deformation of the light-mass nucleus Mg using quasi-elastic measurement

    Y. K. Gupta · B. K. Nayak · U. Garg · N. Sensharma · Shahina · R. Gandhi · D. C. Biswas · M. Şenyiğit · K. B. Howard · W. Tan · P. D. O'Malley · K. Hagino and 17 other authors

    Quasi-elastic scattering measurements have been performed using O and Mg projectiles off Zr at energies around the Coulomb barrier. Experimental data have been analyzed in the framework of coupled channels (CC) calculations using the code CCFULL. The quasi-elastic scattering excitation function and derived barrier distribution for O + Zr reaction are well reproduced by the CC calculations using the vibrational coupling strengths for Zr reported in the literature. Using these vibrational coupling strengths, a Bayesian analysis is carried out for Mg + Zr reaction. The and values for Mg are determined to be and , respectively. The parameter determined in the present work is in good agreement with results obtained using inelastic scattering probes. The hexadecapole deformation of Mg has been measured very precisely for the first time. Present results establish that quasi-elastic scattering could provide a useful probe to determine the ground state deformation of atomic nuclei.

    Comments:
    This is a slightly modified version, accepted for publication in Phys. Lett. B
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1811.12756 [pdf]
    PLB(2020)·40 citations
  6. 06

    [Submitted on 30 Nov 2018] (cross-list from hep-lat)

    Equation of state in (2+1) flavor QCD at high temperatures

    Johannes Heinrich Weber🇺🇸 · Alexei Bazavov🇺🇸 · Peter Petreczky🇺🇸

    We calculate the Equation of State at high temperatures in (2+1) flavor QCD using the highly improved staggered quark (HISQ) action. We study the lattice spacing dependence of the pressure at high temperatures using lattices with temporal extent and and perform continuum extrapolations. We also give a continuum estimate for the Equation of State up to temperatures GeV, which are then compared with results of the weak-coupling calculations. We find reasonable agreement with the HTL calculation at the highest temperatures and a tension with the EQCD calculation of a few percent, with the lattice results in the middle between both.

    Comments:
    Parallel talk at the XIIIth Quark Confinement and the Hadron Spectrum conference. 12 pages, 8 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.12902 [pdf]
    PoS(2019)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE