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Nuclear Theory·nucl-th

Wednesday·February 5, 2020

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 3 Feb 2020]

    Large- analysis of magnetic and axial two-nucleon currents in pionless effective field theory

    Thomas R. Richardson🇺🇸 · Matthias R. Schindler🇺🇸

    We analyze magnetic and axial two-nucleon contact terms in a combined large- and pionless effective field theory expansion. These terms play important roles in correctly describing, e.g., the low-energy cross section of radiative neutron capture and the deuteron magnetic moment. We show that the large- expansion hints towards a hierarchy between the two leading-order magnetic terms that matches that found in phenomenological fits. We also comment on the issue of naturalness in different Lagrangian bases.

    Comments:
    10 pages, 1 figure, version accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2002.00986 [pdf]
    PRC(2020)·10 citations
  2. 02

    [Submitted on 4 Feb 2020]

    Constraining input parameters of AMPT model with meson production

    Katyayni Tiwari🇮🇳 · Md. Nasim🇮🇳

    A Multi-Phase Transport Model (AMPT) has been extensively used to understand the physics behind the experimental observation. Like other models, the outcome of the AMPT model depends on the initial parameters. Therefore, one needs to choose suitable initial parameters before using the model. Lund string fragmentation function has been used to create quark-antiquarks pairs in the AMPT model. The Lund string fragmentation parameters determine the yields and transverse momentum () spectra of particles produced in nucleus-nucleus collisions. The values of Lund string fragmentation parameters were determined by fitting the charged particle yield and spectra measured in the experiment. In this paper, we have shown the yield of strange quarks carrying hadrons, e.g. mesons, are more sensitive to Lund string fragmentation parameters compared to non-strange pions. Using meson spectra measured at RHIC, we have obtained new sets of Lund parameters for Au+Au collisions at = 11.5, 39, and 200 GeV. We have found that using the same set of parameters, we can explain -meson yield at = 39 and 200 GeV, however, we need a different set of parameters for = 11.5 GeV. This suggests that at low energy, = 11.5 GeV, the underlying mechanism for particle production is different compared to top RHIC energies. We have also predicted invariant yield of and mesons as a function of in U+U collisions at = 196 GeV to be measured by STAR experiment.

    Comments:
    13 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2002.01201 [pdf]
    NPA(2020)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE