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Nuclear Theory·nucl-th

Tuesday·July 7, 2020

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    Diffractive two-meson electroproduction with a nucleon and deuteron target

    W. Cosyn🇺🇸 · B. Pire🇫🇷 · L. Szymanowski🇵🇱

    The diffractive electro- or photo-production of two mesons separated by a large rapidity gap gives access to generalized parton distributions (GPDs) in a very specific way. First, these reactions allow to easily access the chiral-odd transversity quark GPDs by selecting one of the produced vector meson to be transversely polarized. Second, they are only sensitive to the so-called ERBL region where GPDs are not much constrained by forward quark distributions. Third, the skewness parameter is not related to the Bjorken variable, but to the size of the rapidity gap. We analyze different channels ( and production) on nucleon and deuteron targets. The analysis is performed in the kinematical domain where a large momentum transfer from the photon to the diffractively produced vector meson introduces a hard scale (the virtuality of the exchanged hard Pomeron). This enables the description of the hadronic part of the process in the framework of collinear factorization of GPDs. We show that the unpolarized cross sections depend very much on the parameterizations of both chiral-even and chiral-odd quark distributions of the nucleon, as well as on the shape of the meson distribution amplitudes. The rates are shown to be in the range of the capacities of a future electron-ion collider.

    ↳ hep-phnucl-exnucl-thPRD(2020)·5 citations
  2. 08

    Generalized Rastall's gravity and its effects on compact objects

    Clésio E. Mota🇧🇷 · Luis C. N. Santos🇧🇷 · Franciele M. da Silva🇧🇷 · Guilherme Grams🇫🇷 · Iarley P. Lobo🇧🇷 · Débora P. Menezes🇧🇷

    We present a generalization of Rastall's gravity in which the conservation law of the energy-momentum tensor is altered, and as a result, the trace of the energy-momentum tensor is taken into account together with the Ricci scalar in the expression for the covariant derivative. Afterwards, we obtain the field equations in this theory and solve them by considering a spherically symmetric space-time. We show that the external solution has two possible classes of solutions with spherical symmetry in the vacuum in generalized Rastall's gravity, and we analyse one of them explicitly. The generalization, in contrast to constant value in general relativity, has a gravitational parameter that depends on the Rastall constant . As an application, we perform a careful analysis of the effects of the theory on neutron stars using realistic equations of state (EoS) as input. Our results show that important differences on the profile of neutron stars are obtained within two representatives EoS.

    ↳ gr-qcastro-ph.HEnucl-thInt.J.Mod.Phys.D(2022)·34 citations
  3. 09

    GW190814's secondary component with mass M as a super-fast pulsar

    Nai-Bo Zhang · Bao-An Li

    Using Stergioulas's RNS code for investigating fast pulsars with Equation of States (EOSs) on the causality surface (where the speed of sound equals that of light) of the high-density EOS parameter space satisfying all known constraints from both nuclear physics and astrophysics, we show that one possible explanation for the GW190814's secondary component of mass M is that it is a super-fast pulsar spinning faster than 971 Hz about 42\% below its Kepler frequency. If confirmed, it would be the fastest pulsar with the highest mass observed presently. There is a large and physically allowed EOS parameter space below the causality surface where pulsars heavier than 2.50 M are supported if they can rotate even faster with critical frequencies depending strongly on the high-density behavior of nuclear symmetry energy.

    ↳ astro-ph.HEnucl-exnucl-thApJ(2020)·118 citations
  4. 10

    Probing topological order of QCD at Electron Ion Collider

    Kirill Tuchin🇺🇸

    The idea that the nuclear matter may posses long range topological order is supported by the theory and the lattice calculations. At high temperature this order is instrumental in producing anomalous phenomena such as the Chiral Magnetic Effect. In the cold nuclear matter it affects the gluon distribution in the nuclear wave function at low . The effect of the topological order is encapsulated in the unintegrated gluon distribution functions which are proportional, at the leading order, to the square of the gluon propagator at finite topological charge density. It is argued that the Electron Ion Collider is well suited to study the topological order of the cold nuclear matter.

    ↳ hep-phnucl-exnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE