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Nuclear Theory·nucl-th

Monday·November 5, 2018

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

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

    Determining the Nonperturbative Collins-Soper Kernel From Lattice QCD

    Markus A. Ebert🇺🇸 · Iain W. Stewart🇺🇸 · Yong Zhao🇺🇸

    At small transverse momentum , transverse-momentum dependent parton distribution functions (TMDPDFs) arise as genuinely nonperturbative objects that describe Drell-Yan like processes in hadron collisions as well as semi-inclusive deep-inelastic scattering. TMDPDFs naturally depend on the hadron momentum, and the associated evolution is determined by the Collins-Soper equation. For the corresponding evolution kernel (or anomalous dimension) is nonperturbative and must be determined as an independent ingredient in order to relate TMDPDFs at different scales. We propose a method to extract this kernel using lattice QCD and the Large-Momentum Effective Theory, where the physical TMD correlation involving light-like paths is approximated by a quasi TMDPDF, defined using equal-time correlation functions with a large-momentum hadron state. The kernel is determined from a ratio of quasi TMDPDFs extracted at different hadron momenta.

    Comments:
    9 pages, 2 figures; v2: extended the review of TMDPDF commonalities, version submitted to PRD; v3: minor changes, journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1811.00026 [pdf]
    PRD(2019)·129 citations
  2. 07

    [Submitted on 2 Nov 2018] (cross-list from astro-ph.HE)

    Hyperonic stars and the symmetry energy

    Constança Providência🇵🇹 · Morgan Fortin🇵🇱 · Helena Pais🇵🇹 · Aziz Rabhi🇺🇸

    In the present study we analyse the effect of the density dependence of the symmetry energy on the hyperonic content of neutron stars within a relativistic mean field description of stellar matter. For the -hyperon, we consider parametrizations calibrated to -hypernuclei. For the and -hyperons uncertainties that reflect the present lack of experimental information on and -hypernuclei are taken into account. We perform our study considering nuclear equations of state that predict two solar mass stars, and satisfy other well settled nuclear matter properties. The effect of the presence of hyperons on the radius, the direct Urca processes, and the cooling of accreting neutron stars are discussed. We show that some star properties are affected in a similar way by the density dependence of the symmetry energy and the hyperon content of the star. To disentangle these two effects it is essential to have a good knowledge of the equation of state at supra-saturation densities. The density dependence of the symmetry energy affects the order of appearance of the different hyperons, which may have direct implications on the neutron star cooling as different hyperonic neutrino processes processes may operate at the center of massive stars. For models which allow for the direct Urca process to operate, hyperonic and purely nucleonic ones are shown to have a similar luminosity when hyperons are included in agreement with modern experimental data. It is shown that for a density dependent hadronic model constrained by experimental, theoretical and observational data, the low-luminosity of SAX J can only be modelled for a hyperonic NS, suggesting that hyperons could be present in its core.

    Comments:
    17 pages, 11 figures, 5 tables
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1811.00786 [pdf]
    Front. Astron. Space Sci., 26 March 2019·62 citations
  3. 08

    [Submitted on 2 Nov 2018] (cross-list from hep-ph)

    Constituent quark number scaling from strange hadron spectra in collisions at 13 TeV

    Jian-wei Zhang🇨🇳 · Hai-hong Li🇨🇳 · Feng-lan Shao🇨🇳 · Jun Song🇨🇳

    We show that the data of spectra of and at midrapidity in inelastic events in collisions at 13 TeV exhibit a constituent quark number scaling property, which is a clear signal of quark combination mechanism at hadronization. We use a quark combination model under equal velocity combination approximation to systematically study the production of identified hadrons in collisions at = 13 TeV. The midrapidity data of spectra of proton, , , , and in inelastic events are simultaneously well fitted by the model. The data of multiplicity dependency of yields of these hadrons are also well understood. The strong dependence for data of ratio is well explained by the model, which further suggests that the production of two hadrons with similar masses is determined by their quark contents at hadronization. spectra of strange hadrons at midrapidity in different multiplicity classes in collisions at 13 TeV are predicted to further test the model in the future. The midrapidity spectra of soft ( GeV/c) strange quark and up/down quark at hadronization in collisions at 13 TeV are extracted.

    Comments:
    13 pages, 14 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.00975 [pdf]
    CPC(2020)·12 citations
  4. 09

    [Submitted on 2 Nov 2018] (cross-list from hep-ph)

    Quark mass function from a one-gluon-exchange-type interaction in Minkowski space

    Elmar P. Biernat🇵🇹 · Franz Gross🇺🇸 · M. T Peña🇵🇹 · Alfred Stadler🇵🇹 · Sofia Leitão🇵🇹

    We present first results for the quark mass function in Minkowski space in both the spacelike and timelike regions calculated from the same quark-antiquark interaction kernel used in the latest meson calculations using the Gross equation. This kernel consists of a Lorentz vector effective one-gluon-exchange-type interaction, a vector constant, and a mixed scalar-pseudoscalar covariant linear confining interaction that does not contribute to the mass function. We analyze the gauge dependence of our results, prove the gauge independence of the constituent quark mass and mass gap equation, and identify the Yennie gauge as the appropriate gauge to be used in CST calculations. We compare our results in the spacelike region to lattice QCD data and find good agreement.

    Comments:
    18 pages, 10 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.01003 [pdf]
    PRD(2018)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE