PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·July 15, 2021

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 01

    Neutron skin thickness of Pb, Sn, and Ca determined from reaction cross sections of He scattering

    Masayuki Matsuzaki · Shingo Tagami · Masanobu Yahiro

    [Background] We constructed the Kyushu chiral -matrix and confirmed its reliability at ~MeV and ~MeV for C scattering. Reaction cross section data of He scattering are available for some nuclides including Pb. PREX II collaboration reported a thick neutron skin for Pb. [Purpose] Our purpose is to deduce neutron skin thicknesses of Pb and some other nuclides from reaction cross sections calculated in terms of the double folding model with the -matrix. [Methods] We fold the -matrix and densities given by mean field calculations. In order to remedy less-constrainedness of the neutron sector, we renormalize densities so as to reproduce the observed cross sections. [Results] We found that a 3.4~ renormalization is necessary for Pb. The neutron density obtained from renormalization results in 0.4160.146 fm by confronting the precision proton radius. [Conclusions] Our result is consistent with PREX II and therefore supports larger slope parameter . Results for Ca and Sn are also consistent with deduced from other experiments. For Sn the present method gives thicker skins.

    nucl-thPRC(2021)·15 citations
  2. 02

    Nucleon-nucleon potentials from Delta-full chiral effective-field-theory and implications

    Y. Nosyk · D. R. Entem · R. Machleidt

    We closely investigate NN potentials based upon the Delta-full version of chiral effective field theory. We find that recently constructed NN potentials of this kind, which (when applied together with three-nucleon forces) were presented as predicting accurate binding energies and radii for a range of nuclei from A=16 to A=132 and providing accurate equations of state for nuclear matter, yield a chi^2/datum of 60 for the reproduction of the pp data below 100 MeV laboratory energy. This chi^2 is more than three times what the Hamada-Johnston potential of the year of 1962 achieved already some 60 years ago. We perceive this historical fact as concerning in view of the current emphasis on precision. We are able to trace the very large chi^2 as well as the apparent success of the potentials in nuclear structure to unrealistic predictions for P-wave states, in which the Delta-full NNLO potentials are off by up to 40 times the NNLO truncation errors. In fact, we show that, the worse the description of the P-wave states, the better the predictions in nuclear structure. Thus, these potentials cannot be seen as the solution to the outstanding problems in current miscroscopic nuclear structure physics.

    nucl-thastro-ph.SRhep-phnucl-exPRC(2021)·31 citations
  3. 03

    Single-energy partial wave analysis for pion photoproduction with fixed-t analyticity

    H. Osmanović🇧🇦 · M. Hadžimehmedović🇧🇦 · R. Omerović🇧🇦 · J. Stahov🇧🇦 · V. Kashevarov🇩🇪 · M. Ostrick🇩🇪 · L. Tiator🇩🇪 · A. Švarc🇭🇷

    Experimental data for pion photoproduction including differential cross sections and various polarization observables from four reaction channels, , , and from threshold up to GeV have been used in order to perform a single-energy partial wave analysis with minimal model dependence by imposing constraints from unitarity and fixed- analyticity in an iterative procedure. Reaction models were only used as starting point in the very first iteration. We demonstrate that with this procedure partial wave amplitudes can be obtained which show only a minimal dependence on the initial model assumptions. The analysis has been obtained in full isospin, and the Watson theorem is enforced for energies below GeV but is even fulfilled up to GeV in many partial waves. Electromagnetic multipoles and are presented and discussed for and -waves.

    nucl-thPRC(2021)·8 citations
  4. 04

    Hot and Dense Matter Equation of State Probability Distributions for Astrophysical Simulations

    Xingfu Du · Andrew W. Steiner · Jeremy W. Holt

    We add an ensemble of nuclei to the equation of state for homogeneous nucleonic matter to generate a new set of models suitable for astrophysical simulations of core-collapse supernovae and neutron star mergers. We implement empirical constraints from (i) nuclear mass measurements, (ii) proton-proton scattering phase shifts, and (iii) neutron star observations. Our model is also guided by microscopic many-body theory calculations based on realistic nuclear forces, including the zero-temperature neutron matter equation of state from quantum Monte Carlo simulations and thermal contributions to the free energy from finite-temperature many-body perturbation theory. We ensure that the parameters of our model can be varied while preserving thermodynamic consistency and the connection to experimental or observational data, thus providing a probability distribution of the astrophysical hot and dense matter equation of state. We compare our results with those obtained from other available equations of state. While our probability distributions indeed represent a large number of possible equations of state, we cannot yet claim to have fully explored all of the uncertainties, especially with regard to the structure of nuclei in the hot and dense medium.

    nucl-thastro-ph.HEastro-ph.SRPRC(2022)·21 citations
  5. 05

    Progress and Opportunities in Backward angle (u-channel) Physics

    C. Ayerbe Gayoso🇺🇸 · Ł. Bibrzycki🇵🇱 · S. Diehl🇩🇪 · S. Heppelmann🇺🇸 · D.W. Higinbotham🇺🇸 · G.M. Huber🇨🇦 · S.J.D. Kay🇨🇦 · S.R. Klein🇺🇸 · J.M. Laget🇺🇸 · W.B. Li🇺🇸 · V. Mathieu🇪🇸 · K. Park🇺🇸 and 8 other authors

    Backward angle (u-channel) scattering provides complementary information for studies of hadron spectroscopy and structure, but has been less comprehensively studied than the corresponding forward angle case. As a result, the physics of u-channel scattering poses a range of new experimental and theoretical opportunities and questions. We summarize recent progress in measuring and understanding high energy reactions with baryon charge exchange in the u-channel, as discussed in the first backward angle (u-channel) Physics Workshop. In particular, we discuss backward angle measurements and their theoretical description via both hadronic models and the collinear factorization approach, and discuss planned future measurements of u-channel physics. Finally, we propose outstanding questions and challenges for u-channel physics.

    ↳ hep-phnucl-exnucl-thEPJA(2021)·22 citations
  6. 06

    Impact of the nuclear symmetry energy on the post-merger phase of a binary neutron star coalescence

    Elias R. Most · Carolyn A. Raithel

    The nuclear symmetry energy plays a key role in determining the equation of state of dense, neutron-rich matter, which governs the properties of both terrestrial nuclear matter as well as astrophysical neutron stars. A recent measurement of the neutron skin thickness from the PREX collaboration has lead to new constraints on the slope of the nuclear symmetry energy, L, which can be directly compared to inferences from gravitational-wave observations of the first binary neutron star merger inspiral, GW170817 In this paper, we explore a new regime for potentially constraining the slope, L, of the nuclear symmetry energy with future gravitational wave events: the post-merger phase a binary neutron star coalescence. In particular, we go beyond the inspiral phase, where imprints of the slope parameter L may be inferred from measurements of the tidal deformability, to consider imprints on the post-merger dynamics, gravitational wave emission, and dynamical mass ejection. To this end, we perform a set of targeted neutron star merger simulations in full general relativity using new finite-temperature equations of state, which systematically vary L. We find that the post-merger dynamics and gravitational wave emission are mostly insensitive to the slope of the nuclear symmetry energy. In contrast, we find that dynamical mass ejection contains a weak imprint of L, with large values of L leading to systematically enhanced ejecta.

    ↳ astro-ph.HEgr-qcnucl-thPRD(2021)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE