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Nuclear Theory·nucl-th

Monday·February 22, 2021

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    Dynamical Screening Effects on Big Bang Nucleosynthesis

    Eunseok Hwang🇰🇷 · Dukjae Jang🇰🇷 · Kiwan Park🇰🇷 · Motohiko Kusakabe🇨🇳 · Toshitaka Kajino🇨🇳 · A. Baha Balantekin🇯🇵 · Tomoyuki Maruyama🇯🇵 · Chang-Mo Ryu🇰🇷 · Myung-Ki Cheoun🇰🇷

    A moving ion in plasma creates a deformed electric potential depending on the ion velocity, which leads to the distinct screening effect compared to the standard static Salpeter formula. In this paper, adopting the test charge method, we explore the dynamical screening effects on big bang nucleosynthesis (BBN). We find that the high temperature in the early universe causes the ion velocity to be faster than the solar condition so that the electric potential is effectively polarized. However, the low density of background plasma components significantly suppresses the dynamical screening effects on thermonuclear reaction rates during the BBN epoch. We compare our results with several thermonuclear reaction rates for solar fusion considering the dynamical screening effects. Also, we discuss the additional plasma properties in other astrophysical sites for the possible expansion from the present calculation in the future.

    nucl-thastro-ph.COJCAP(2021)·13 citations
  2. 02

    Comprehensive investigation of the symmetric space-star configuration in the nucleon-deuteron breakup

    H. Witala · J. Golak · R. Skibinski · K. Topolnicki · E. Epelbaum · H. Krebs · P. Reinert

    We examine a description of available cross section data for symmetric space star (SST) configurations in the neutron-deuteron (nd) and proton-deuteron (pd) breakup reaction using numerically exact solutions of the three-nucleon (3N) Faddeev equation based on two- and three-nucleon (semi)phenomenological and chiral forces. The predicted SST cross sections are very stable with respect to the underlying dynamics for incoming nucleon laboratory energies below MeV. We discuss possible origins of the surprising discrepancies between theory and data found in low-energy nd and pd SST breakup measurements.

    nucl-thPRC(2021)·12 citations
  3. 03

    Astrophysical Constraints on the Symmetry Energy and the Neutron Skin of Pb with Minimal Modeling Assumptions

    Reed Essick · Ingo Tews · Philippe Landry · Achim Schwenk

    The symmetry energy and its density dependence are crucial inputs for many nuclear physics and astrophysics applications, as they determine properties ranging from the neutron-skin thickness of nuclei to the crust thickness and the radius of neutron stars. Recently, PREX-II reported a value of fm for the neutron-skin thickness of Pb, implying a slope parameter MeV, larger than most ranges obtained from microscopic calculations and other nuclear experiments. We use a nonparametric equation of state representation based on Gaussian processes to constrain the symmetry energy , , and directly from observations of neutron stars with minimal modeling assumptions. The resulting astrophysical constraints from heavy pulsar masses, LIGO/Virgo, and NICER clearly favor smaller values of the neutron skin and , as well as negative symmetry incompressibilities. Combining astrophysical data with PREX-II and chiral effective field theory constraints yields MeV, MeV, and fm.

    nucl-thastro-ph.HEnucl-exPRL(2021)·225 citations
  4. 04

    The Doubly-heavy Tetraquarks () in a Constituent Quark Model with a Complete Set of Harmonic Oscillator Bases

    Sungsik Noh🇰🇷 · Woosung Park🇰🇷 · Su Houng Lee🇰🇷

    We have improved our previous variational method based constituent quark model by introducing a complete set of 3-dimensional harmonic oscillator bases as the spatial part of the total wave function. To assess the validity of our approach, we compared the binding energy, thus calculated with the exact value for the hydrogen model. After fitting to the masses of the ground state hadrons, we apply our new method to analyze the doubly-heavy tetraquark states and compared the result for the binding energies with that from other works. We also calculated the ground state masses of and with . We found that and , both with , are stable against the two lowest threshold meson states with binding energies MeV and MeV, respectively. We further found that is near the lowest threshold. The spatial sizes for the tetraquarks are also discussed.

    ↳ hep-phnucl-thPRD(2021)·53 citations
  5. 05

    Screening masses towards chiral limit

    Simon Dentinger🇩🇪 · Olaf Kaczmarek🇩🇪 · Anirban Lahiri🇩🇪

    A possible effective restoration of the anomalous symmetry would have a non-trivial effect on the global phase diagram of QCD. In this work we investigate the effective restoration of the through the calculation of scalar and pseudo-scalar screening masses and corresponding susceptibilities, for physical and lower than physical pion masses. Calculations have been performed in (2+1)-flavor HISQ discretization scheme with a physical value of the strange quark mass. Preliminary calculations of the continuum extrapolated scalar and pseudo-scalar masses are presented, based on lattices with three different temporal extent. Non-trivial structure of the difference between scalar and pseudo-scalar susceptibilites are discussed for lattices.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·8 citations
  6. 06

    Evolution of initial stage fluctuations in the glasma

    Pablo Guerrero-Rodríguez🇫🇮 · Tuomas Lappi🇫🇮

    We perform a calculation of the one- and two-point correlation functions of energy density and axial charge deposited in the glasma in the initial stage of a heavy ion collision at finite proper time. We do this by describing the initial stage of heavy ion collisions in terms of freely evolving classical fields whose dynamics obey the linearized Yang-Mills equations. Our approach allows us to systematically resum the contributions of high momentum modes that would make a power series expansion in proper time divergent. We evaluate the field correlators in the McLerran-Venugopalan model using the glasma graph approximation, but our approach for the time dependence can be applied to a general four-point function of the initial color fields. Our results provide analytical insight into the preequilibrium phase of heavy ion collisions without requiring a numerical solution to the Yang-Mills equations.

    ↳ hep-phnucl-thPRD(2021)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE