PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·July 28, 2020

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    [Submitted on 25 Jul 2020]

    Importance of Multiplicity Fluctuations in Entropy Scaling

    Patrick Carzon🇺🇸 · Matthew D. Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    One of the greatest uncertainties in heavy-ion collisions is the description of the initial state. Different models predict a wide range of initial energy density distributions based on their underlying assumptions. Final flow harmonics are sensitive to these differences in the initial state due to the nearly linear mapping between eccentricities and anisotropic flow harmonics. The Trento code uses a model-agnostic approach by phenomenologically parameterizing the initial state and constraining those parameters from a Bayesian analysis. There the multiplicity fluctuations were determined by a one parameter distribution. However, initial-state models arising from the Color-Glass Condensate (CGC) framework lead to an initial energy density which is outside the functional form considered in Trento and its later Bayesian analyses because they rely on log-normal multiplicity fluctuations. We compare scaling (CGC-like) to scaling (preferred from a Trento Bayesian analysis) and find that the form together with log-normal fluctuations is a reasonable candidate to describe the multiplicity fluctuations but leads to larger eccentricities, which would affect the extraction of viscosity in small systems.

    Comments:
    4 pages, 2 figures, 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2007.12977 [pdf]
    PoS(2021)·5 citations
  2. 02

    [Submitted on 26 Jul 2020]

    Asymptotic normalization coefficient method for two-proton radiative capture

    L.V. Grigorenko · Yu.L. Parfenova · N.B. Shulgina · M.V. Zhukov

    The method of asymptotic normalization coefficients is a standard approach for studies of two-body non-resonant radiative capture processes in nuclear astrophysics. This method suggests a fully analytical description of the radiative capture cross section in the low-energy region of the astrophysical interest. We demonstrate how this method can be generalized to the case of three-body radiative captures. It was found that an essential feature of this process is the highly correlated nature of the capture. This reflects the complexity of three-body Coulomb continuum problem. Radiative capture O++Ne+ is considered as an illustration.

    Comments:
    9 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.13139 [pdf]
    PLB(2020)·3 citations
  4. 04

    [Submitted on 27 Jul 2020]

    Low-energy cluster vibrations in N = Z nuclei

    F. Mercier🇫🇷 · A. Bjelčić🇭🇷 · T. Nikšić🇭🇷 · J.-P. Ebran🇫🇷 · E. Khan🇫🇷 · D. Vretenar🇭🇷

    Significant transition strength in light -conjugate nuclei at low energy, typically below 10 MeV, has been observed in many experiments. In this work the isoscalar low-energy response of N=Z nuclei is explored using the Finite Amplitude Method (FAM) based on the microscopic framework of nuclear energy density functionals. Depending on the multipolarity of the excitation and the equilibrium deformation of a particular isotope, the low-energy strength functions display prominent peaks that can be attributed to vibration of cluster structures: +C+ and +O in Ne, C+C in Mg, 4+C in Si, etc. Such cluster excitations are favored in light nuclei with large deformation.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.13358 [pdf]
    PRC(2021)·13 citations
  5. 05

    [Submitted on 27 Jul 2020]

    Speed of sound constraints from tidal deformability of neutron stars

    A. Kanakis-Pegios · P.S. Koliogiannis · Ch.C. Moustakidis

    The upper bound of the speed of sound in dense nuclear matter is one of the most interesting but still unsolved problems in Nuclear Physics. Theoretical studies in connection with recent observational data of isolated neutron stars as well as binary neutron stars systems offer an excellent opportunity to shed light on this problem. In the present work, we suggest a method to directly relate the measured tidal deformability (polarizability) of binary neutron stars system (before merger) to the maximum neutron star mass scenario and possible upper bound on the speed of sound. This method is based on the simple but efficient idea that while the upper limit of the effective tidal deformability favors soft equations of state, the recent high measured values of neutron star mass favor stiff ones. In the present work, firstly, using a simple well established model we parametrize the stiffness of the equation of state with the help of the speed of sound. Secondly, in comparison with the recent observations by LIGO/VIRGO collaboration of two events, GW170817 and GW190425, we suggest possible robust constraints. Moreover, we evaluate and postulate, in the framework of the present method, what kind of future measurements could help us to improve the stringent of the constraints on the neutron star equation of state.

    Comments:
    v1: 13 pages, 7 figures, 2 tables. v2: 13 pages, 7 figures, 2 tables; accepted for publication in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
    arXiv:
    2007.13399 [pdf]
    PRC(2020)·59 citations
  6. 06

    [Submitted on 27 Jul 2020]

    Two-Pion-Exchange contributions to the nucleon-nucleon interactions in covariant baryon chiral perturbation theory

    Yang Xiao🇨🇳 · Chun-Xuan Wang🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

    Employing the covariant baryon chiral perturbation theory, we calculate the leading and next-to-leading order two-pion exchange (TPE) contributions to interaction up to order . We compare the so-obtained phase shifts with and mixing angles with with those obtained in the nonrelativistic baryon chiral perturbation theory, which allows us to check the relativistic corrections to the medium-range part of interactions. We show that the contributions of relativistic TPE are more moderate than those of the nonrelativistic TPE. The relativistic corrections play an important role in F-waves especially the partial wave. Moreover, the relativistic results seem to converge faster than the nonrelativistic results in almost all the partial waves studied in the present work, consistent with the studies performed in the one-baryon sector.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2007.13675 [pdf]
    PRC(2020)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE