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Nuclear Theory·nucl-th

Friday·June 25, 2021

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    [Submitted on 24 Jun 2021] (cross-list from hep-ph)

    Higher-order corrections to exclusive heavy vector meson production

    Tuomas Lappi🇫🇮 · Heikki Mäntysaari🇫🇮 · Jani Penttala🇫🇮

    We present results for higher-order corrections to exclusive production. This includes the first relativistic correction of order in quark velocity, and next-to-leading order corrections in for longitudinally polarized production. The relativistic corrections are found to be important for a good description of the HERA data, especially at small values of the photon virtuality. The next-to-leading order results for longitudinal production are evaluated numerically. We also demonstrate how the vector meson production provides complementary information to the structure functions for extracting the initial condition for the small- evolution of the dipole-proton scattering amplitude.

    Comments:
    Submission to SciPost, 6 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.12825 [pdf]
    SciPost Phys.Proc.(2022)·8 citations
  2. 07

    [Submitted on 24 Jun 2021] (cross-list from astro-ph.HE)

    Influence of the crust on the neutron star macrophysical quantities and universal relations

    Lami Suleiman🇵🇱 · Morgane Fortin🇵🇱 · Julian Leszek Zdunik🇵🇱 · Pawel Haensel🇵🇱

    Measurements of neutron-star macrophysical properties thanks to multimessenger observations offer the possibility to constrain the properties of nuclear matter. Indeed cold and dense matter as found inside neutron stars, in particular in their core, is not accessible to terrestrial laboratories.We investigate the consequences of using equations of state that employ models for the core and the crust that are not calculated consistently on the neutron-star macrophysical properties, on some of the so-called universal relations and on the constraints obtained from gravitational-wave observations. We use various treatments found in the literature to connect together nonconsistent core and crust equations of state. We then compute the mass, the radius, the tidal deformability, and the moment of inertia for each model. Finally, we assess the discrepancies in the neutron-star macrophysical properties obtained when consistent models for the whole star and nonconsistent ones are employed. The use of crust models nonconsistent with the core introduces an error on the macrophysical parameters which can be as large as the estimated accuracy of current and next generation telescopes. The precision of some of the universal relations reported in the literature is found to be overestimated. We confirm that the equation of the crust has limited influence on the macrophysical properties. The discrepancy between results obtained for a fully consistent equation of state and a nonconsistent one can be reduced if one connects the core and the crust models at baryon densities around 0.08-0.1 fm. The equation of the crust cannot be probed with current multimessenger observations and near-future ones.

    Comments:
    19 pages, 12 figures, 3 tables. Accepted for publication in PRC
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2106.12845 [pdf]
    PRC(2021)·51 citations
  3. 08

    [Submitted on 24 Jun 2021] (cross-list from cond-mat.quant-gas)

    Unitary -wave Fermi gas in one dimension

    Hiroyuki Tajima · Shoichiro Tsutsui · Takahiro M. Doi · Kei Iida

    We elucidate universal many-body properties of a one-dimensional, two-component ultracold Fermi gas near the -wave Feshbach resonance. The low-energy scattering in this system can be characterized by two parameters, that is, -wave scattering length and effective range. At the unitarity limit where the -wave scattering length diverges and the effective range is reduced to zero without conflicting with the causality bound, the system obeys universal thermodynamics as observed in a unitary Fermi gas with contact -wave interaction in three dimensions. It is in contrast to a Fermi gas with the -wave resonance in three dimensions in which the effective range is inevitably finite. We present the universal equation of state in this unitary -wave Fermi gas within the many-body -matrix approach as well as the virial expansion method. Moreover, we examine the single-particle spectral function in the high-density regime where the virial expansion is no longer valid. On the basis of the Hartree-like self-energy shift at the divergent scattering length, we conjecture that the equivalence of the Bertsch parameter across spatial dimensions holds even for a one-dimensional unitary -wave Fermi gas.

    Comments:
    9 pages, 5 figures
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
    arXiv:
    2106.12909 [pdf]
    PRA(2021)·10 citations
  4. 09

    [Submitted on 24 Jun 2021] (cross-list from physics.comp-ph)

    On the Application of the Analytical Discrete Ordinates Method to the Solution of Nonclassical Transport Problems in Slab Geometry

    Leonardo R. C. Moraes · Liliane B. Barichello · Ricardo C. Barros · Richard Vasques

    In this work we investigate the use of the Analytical Discrete Ordinates (ADO) method when solving the spectral approximation of the nonclassical transport equation. The spectral approximation is a recently developed method based on the representation of the nonclassical angular flux as a series of Laguerre polynomials. This representation generates, as outcome, a system of equations that have the form of classical transport equations and can therefore be solved by current deterministic algorithms. Thus, the investigation of efficient approaches to solve the nonclassical transport equation is of interest and shall be pursued. This is the case of the ADO method which has been successfully used to solve a wide class of problems in the general area of particle transport. Numerical results are presented for two nonclassical test problems in slab geometry. These nonclassical transport problems are chosen in such way that their solution exactly reproduces the solution of the classical diffusion problem. Very accurate results are obtained for both test problems. However, the use of high precision arithmetic is sometimes required as illustrated in the second test problem. Limitations of the spectral approximation are also analyzed and discussed.

    Subjects:
    Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.13149 [pdf]
    J.Comput.Phys.(2022)·1 citation
  5. 10

    [Submitted on 24 Jun 2021] (cross-list from hep-ph)

    Short-distance constraints for the longitudinal component of the hadronic light-by-light amplitude: an update

    Gilberto Colangelo🇨🇭 · Franziska Hagelstein🇨🇭 · Martin Hoferichter🇨🇭 · Laetitia Laub🇨🇭 · Peter Stoffer🇦🇹

    We reassess the impact of short-distance constraints for the longitudinal component of the hadronic light-by-light amplitude on the anomalous magnetic moment of the muon, , by comparing different solutions that have recently appeared in the literature. In particular, we analyze the relevance of the exact axial anomaly and its impact on and conclude that it remains rather limited. We show that all recently proposed solutions agree well within uncertainties on the numerical estimate of the impact of short-distance constraints on , despite differences in the concrete implementation. We also take into account the recently calculated perturbative corrections to the massless quark loop to update our estimate and outline the path towards future improvements.

    Comments:
    14 pages, 6 figures, 1 table, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2106.13222 [pdf]
    EPJC(2021)·73 citations

Affiliations

first authorsco-authorsvia INSPIRE