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Nuclear Theory·nucl-th

Thursday·August 4, 2022

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    Modeling the electric dipole strength of neutron-rich He: Prediction of multineutron collective excitations

    Takayuki Myo · Kiyoshi Kato

    We investigate the multineutron excitations of neutron-rich He in the electric dipole strength using a He++++ five-body model. Many-body unbound states of He are obtained in the complex scaling method. We found that the different excitation modes coexist in the dipole strength below the excitation energy of 20 MeV. The strength below 10 MeV comes from the He+ channel, indicating the sequential breakup of He via the He resonance to He++. Above 10 MeV, the strength is obtained from many-body continuum states with strong configuration mixings, suggesting a new collective motion of four neutrons with the dipole oscillation against He.

    nucl-thnucl-exPRC(2022)·12 citations
  2. 02

    Relativistic dissipative spin hydrodynamics from kinetic theory with a nonlocal collision term

    Nora Weickgenannt🇩🇪 · David Wagner🇩🇪 · Enrico Speranza🇺🇸 · Dirk H. Rischke🇩🇪

    We derive relativistic dissipative spin hydrodynamics from kinetic theory featuring a nonlocal collision term using the method of moments. In this framework, the components of the spin tensor are dynamical variables which obey relaxation-type equations. We find that the corresponding relaxation times are determined by the local part of the collision term, while the nonlocal part contributes to the Navier-Stokes terms in these equations of motion. The spin relaxation time scales are comparable to those of the usual dissipative currents. Finally, the Navier-Stokes limit of the Pauli-Lubanski vector receives contributions proportional to the shear tensor of the fluid, which implies that the polarization of hadrons observed in heavy-ion collisions is influenced by dissipative effects.

    nucl-thPRD(2022)·75 citations
  3. 03

    Jet cone radius dependence of and at PbPb 5.02 TeV from JEWEL++v-USPhydro

    Leonardo Barreto🇧🇷 · Fabio M. Canedo🇧🇷 · Marcelo G. Munhoz🇧🇷 · Jorge Noronha🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    We combine, for the first time, event-by-event initial conditions with the relativistic viscous hydrodynamic model v-USPhydro and the Monte Carlo event generator JEWEL to make predictions for the nuclear modification factor and jet azimuthal anisotropies in PbPb collisions for multiple centralities and values of the jet cone radius . The -dependence of and strongly depends on the presence of recoiling scattering centers. We find a small jet in mid-central collisions and consistent results in wide jet regions and centralities with ATLAS data.

    nucl-thhep-phnucl-exPLB(2025)·18 citations
  4. 04

    Nucleon-pair truncation of the shell model for medium-heavy nuclei

    Y. X. Yu · Y. Lu · G. J. Fu · Calvin W. Johnson · Z. Z. Ren

    Background: Computationally tractable models of atomic nuclei is a long-time goal of nuclear structure physics. A flexible framework which easily includes excited states and many-body correlations is the configuration-interaction shell model (SM), but the exponential growth of the basis means one needs an efficient truncation scheme, ideally one that includes both deformation and pairing correlations. Purpose: We propose an efficient truncation scheme of the SM: starting from a pair condensate variationally defined by Hartree-Fock single-particle states and the particle-number conserved Bardeen-Cooper-Schrieffer (NBCS) approximation, we carry out projection of states with good angular momentum. Methods: After generating Hartree-Fock single-particle states with Kramers degeneracy in a SM space, we optimize the pair amplitudes in the NBCS by minimizing the energy, and then use linear algebra projection (LAP) of states with good angular momentum. Both NBCS and LAP are computationally fast. Results: Our calculations yield good agreement with full configuration-interaction SM calculations for low-lying states of transitional and rotational nuclei with axially symmetric and triaxial deformation in medium- and heavy-mass regions: Ti, Cr, Fe, Zn, Ge, Se, and Xe. We predict low-lying states of and , nuclei difficult to reach by large-scale SM calculations. Conclusions: Both pair correlation and the configuration mixing between different intrinsic states play a key role in reproducing collectivity and shape coexistence, demonstrating the utility of this truncation scheme of the SM to study transitional and deformed nuclei.

    nucl-thPRC(2022)·12 citations
  5. 05

    Nuclear physics uncertainties in light hypernuclei

    D. Gazda🇨🇿 · T. Yadanar Htun🇸🇪 · C. Forssén🇸🇪

    The energy levels of light hypernuclei are experimentally accessible observables that contain valuable information about the interaction between hyperons and nucleons. In this work we study strangeness systems H and He using the ab initio no-core shell model (NCSM) with realistic interactions obtained from chiral effective field theory (EFT). In particular, we quantify the finite precision of theoretical predictions that can be attributed to nuclear physics uncertainties. We study both the convergence of the solution of the many-body problem (method uncertainty) and the regulator- and calibration data-dependence of the nuclear EFT Hamiltonian (model uncertainty). For the former, we implement infrared correction formulas and extrapolate finite-space NCSM results to infinite model space. We then use Bayesian parameter estimation to quantify the resulting method uncertainties. For the latter, we employ a family of 42 realistic Hamiltonians and measure the standard deviation of predictions while keeping the leading-order hyperon-nucleon interaction fixed. Following this procedure we find that model uncertainties of ground-state separation energies amount to keV in H(H,He) and keV in He. Method uncertainties are comparable in magnitude for the H,He excited states and He, which are computed in limited model spaces, but otherwise much smaller. This knowledge of expected theoretical precision is crucial for the use of binding energies of light hypernuclei to infer the elusive hyperon-nucleon interaction.

    nucl-thhep-phnucl-exPRC(2022)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE