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Nuclear Theory·nucl-th

Thursday·August 31, 2017

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    [Submitted on 30 Aug 2017] (cross-list from hep-ph)

    Exploring GPDs through the photoproduction of a pair

    R. Boussarie🇵🇱 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

    We describe the process in the generalized Bjorken regime where the pair has a large invariant mass. In the collinear QCD factorization framework, the amplitude gives access to both chiral-even and chiral-odd quark generalized parton distributions (GPDs), and is insensitive to gluon GPDs. The separation of longitudinally and transversely polarized meson production allows to distinguish chiral-even and chiral-odd contributions. Production rates are estimated in the kinematics of the near-future JLab~12-GeV experiments.

    Comments:
    6 pages, 3 figures, to appear in the proceedings of XXV International Workshop on Deep-Inelastic Scattering and Related Subject - DIS 2017, 3-7 April 2017, University of Birmingham, UK
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1708.09164 [pdf]
    PoS(2018)·3 citations
  2. 04

    [Submitted on 30 Aug 2017] (cross-list from astro-ph.HE)

    Basic parameters of the helium accreting X-ray bursting neutron star in 4U 1820-30

    Valery F. Suleimanov · Jari J.E. Kajava · Sergey V. Molkov · Joonas Nättilä · Alexander A. Lutovinov · Klaus Werner · Juri Poutanen

    The ultracompact low-mass X-ray binary 4U 1820-30 situated in the globular cluster NGC 6624 has an orbital period of only 11.4 min which likely implies a white dwarf companion. The observed X-ray bursts demonstrate a photospheric radius expansion phase and therefore are believed to reach the Eddington luminosity allowing us to estimate the mass and the radius of the neutron star (NS) in this binary. Here we re-analyse all Rossi X-ray Timing Explorer observations of the system and confirm that almost all the bursts took place during the hard persistent state of the system. This allows us to use the recently developed direct cooling tail method to estimate the NS mass and radius. However, because of the very short, about a second, duration of the cooling tail phases that can be described by the theoretical atmosphere models, the obtained constraints on the NS radius are not very strict. Assuming a pure helium NS atmosphere we found that the NS radius is in the range 10-12 km, if the NS mass is below 1.7 , and in a wider range of 8-12 km for a higher 1.7-2.0 NS mass. The method also constrains the distance to the system to be 6.50.5 kpc, which is consistent with the distance to the cluster. For the solar composition atmosphere, the NS parameters are in strong contradiction with the generally accepted range of possible NS masses and radii.

    Comments:
    9 pages, 9 figures, 2 tables, accepted for publication in MNRAS
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1708.09168 [pdf]
    MNRAS(2017)·18 citations
  3. 05

    [Submitted on 30 Aug 2017] (cross-list from hep-ph)

    Coulomb corrections to inclusive cross sections at the future Electron - Ion Collider

    V.P. Goncalves🇧🇷 · M.V.T Machado🇧🇷 · F.S. Navarra🇧🇷 · D. Spiering🇧🇷

    The experimental results of the future electron -- ion () collider are expected to constrain the dynamics of the strong interactions at small values of the Bjorken -- variable and large nuclei. Recently it has been suggested that Coulomb corrections can be important in inclusive and diffractive interactions. In this paper we present a detailed investigation of the impact of the Coulomb corrections to some of the observables that will be measured in the future collider. In particular, we estimate the magnitude of these corrections for the charm and longitudinal cross sections in inclusive and diffractive interactions. Our results demonstrate that the Coulomb corrections for these observables are negligible, which implies that they can be used to probe the QCD dynamics.

    Comments:
    9 pages, 6 figures. Improved version to be published in Physical Review C
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1708.09279 [pdf]
    PRC(2018)·5 citations
  4. 06

    [Submitted on 30 Aug 2017] (cross-list from hep-ph)

    Comment on "Nucleon spin-averaged forward virtual Compton tensor at large Q^2"

    Michael C. Birse🇬🇧 · Judith A. McGovern (Manchester)🇬🇧

    In recent work, Hill and Paz apply the operator product expansion to forward doubly virtual Compton scattering. The resulting large- form of the amplitude is compatible with the one we obtain by extrapolation of low- results from a chiral effective field theory, providing support for our approach. That paper also presents a result for the two-photon contribution to the Lamb shift in muonic hydrogen that has a much larger uncertainty than in previous work. We show that this an overestimate arising from the inclusion of the proton pole term in the subtracted dispersion relation for .

    Comments:
    3 pages; version accepted for publication
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
    arXiv:
    1708.09341 [pdf]
    PRD(2018)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE