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Nuclear Theory·nucl-th

Friday·April 24, 2020

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 01

    Fission of Pu with symmetry-restored density functional theory

    Petar Marević · Nicolas Schunck

    Nuclear fission plays an important role in fundamental and applied science, from astrophysics to nuclear engineering, yet it remains a major challenge to nuclear theory. Theoretical methods used so far to compute fission observables rely on symmetry-breaking schemes where basic information on the number of particles, angular momentum, and parity of the fissioning nucleus is lost. In this work, we analyze the impact of restoring broken symmetries in the benchmark case of Pu.

    nucl-thPRL(2020)·25 citations
  2. 02

    Structure of Krypton Isotopes using the Generalised Bohr Hamiltonian Method

    David Muir · Leszek Próchniak · Alessandro Pastore · Jacek Dobaczewski

    We investigate the properties of the excited spectra of the even-even isotopes of krypton using a Generalised Bohr Hamiltonian with three different Skyrme functionals. In particular, we investigate the evolution of the low-lying and states and their associated electromagnetic transitions. The model reproduces quite nicely the energy trends apart from Kr, where none of the interactions used here are able to grasp a sudden change in the energy spectrum. Additionally, we explore the neutron deficient region Kr which is a proposed region for shape coexistence. We observe that the model can reproduce the structure of the experimental spectrum of Kr exceedingly well.

    nucl-thJ.Phys.Conf.Ser.(2020)·2 citations
  3. 03

    Entropy Production in Dissipationless Hydrodynamics with an order parameter

    Shu Lin · Gezheng Zhou

    We study hydrodynamics coupled to order parameter based on linear sigma model. We obtain numerical solutions for both boost invariant and non-boost invariant solutions. Both solutions show the order parameter rises with oscillations, which persist at late time. The temperature drops with correlated oscillations, which can be approximated by a power law at mid-rapidity. We also find the entropy is conserved in the boost invariant case, but entropy production is seen in non-boost invariant solution. We interpret the entropy production as due to smoothening of inhomogeneity in the off-equilibrium state.

    nucl-th0 citations
  4. 04

    Thresholds of ultraperipheral processes

    I.M. Dremin🇷🇺

    Threshold behavior of the cross sections of ultraperipheral nuclear interactions is studied. Production of and pairs as well as and parapositronium is treated. The values of corresponding energy thresholds are presented and the total cross sections of these processes at the newly constructed NICA and FAIR facilities are estimated.

    nucl-thhep-phInt.J.Mod.Phys.A(2020)·2 citations
  5. 05

    Designing Optimal Experiments: An Application to Proton Compton Scattering

    J. A. Melendez · R. J. Furnstahl · H. W. Griesshammer · J. A. McGovern · D. R. Phillips · M. T. Pratola

    Interpreting measurements requires a physical theory, but the theory's accuracy may vary across the experimental domain. To optimize experimental design, and so to ensure that the substantial resources necessary for modern experiments are focused on acquiring the most valuable data, both the theory uncertainty and the expected pattern of experimental errors must be considered. We develop a Bayesian approach to this problem, and apply it to the example of proton Compton scattering. Chiral Effective Field Theory (EFT) predicts the functional form of the scattering amplitude for this reaction, so that the electromagnetic polarizabilities of the nucleon can be inferred from data. With increasing photon energy, both experimental rates and sensitivities to polarizabilities increase, but the accuracy of EFT decreases. Our physics-based model of EFT truncation errors is combined with present knowledge of the polarizabilities and reasonable assumptions about experimental capabilities at HIS and MAMI to assess the information gain from measuring specific observables at specific kinematics, \emph{i.e.}, to determine the relative amount by which new data are apt to shrink uncertainties. The strongest gains would likely come from new data on the spin observables and at to MeV and to . These would tightly constrain . New data on the differential cross section between and \,MeV and over a wide angle range will substantially improve constraints on , and . Good signals also exist around MeV for and . Such data will be pivotal in the continuing quest to pin down the scalar polarizabilities and refine understanding of the spin polarizabilities.

    nucl-thnucl-exphysics.data-anEPJA(2021)·28 citations
  6. 06

    Astrophysics in the Laboratory: The CBM Experiment at FAIR

    P. Senger · for the CBM collaboration

    The future Facility for Antiproton and Ion Research (FAIR) is an accelerator-based international center for fundamental and applied research, which presently is under construction in Darmstadt, Germany. An important part of the program is devoted to questions related to astrophysics, including the origin of elements in the universe and the properties of strongly interacting matter under extreme conditions, which are relevant for our understanding of the structure of neutron stars and the dynamics of supernova explosions and neutron star mergers. The Compressed Baryonic Matter (CBM) experiment at FAIR is designed to measure promising observables in high-energy heavy-ion collisions, which are expected to be sensitive to the high-density equation-of-state (EOS) of nuclear matter and to new phases of QCD matter at high densities. The CBM physics program, the relevant observables and the experimental setup will be discussed.

    ↳ nucl-exastro-ph.IMhep-exhep-ph+1Particles(2020)·14 citations
  7. 07

    Probing the core of the strong nuclear interaction

    A. Schmidt🇺🇸 · J. R. Pybus🇺🇸 · R. Weiss🇮🇱 · E. P. Segarra🇺🇸 · A. Hrnjic🇺🇸 · A. Denniston🇺🇸 · O. Hen🇺🇸 · E. Piasetzky🇮🇱 · L. B. Weinstein🇺🇸 · N. Barnea🇮🇱 · M. Strikman🇺🇸 · A. Larionov🇩🇪 and 153 other authors

    The strong nuclear interaction between nucleons (protons and neutrons) is the effective force that holds the atomic nucleus together. This force stems from fundamental interactions between quarks and gluons (the constituents of nucleons) that are described by the equations of Quantum Chromodynamics (QCD). However, as these equations cannot be solved directly, physicists resort to describing nuclear interactions using effective models that are well constrained at typical inter-nucleon distances in nuclei but not at shorter distances. This limits our ability to describe high-density nuclear matter such as in the cores of neutron stars. Here we use high-energy electron scattering measurements that isolate nucleon pairs in short-distance, high-momentum configurations thereby accessing a kinematical regime that has not been previously explored by experiments, corresponding to relative momenta above 400 MeV/c. As the relative momentum between two nucleons increases and their separation thereby decreases, we observe a transition from a spin-dependent tensor-force to a predominantly spin-independent scalar-force. These results demonstrate the power of using such measurements to study the nuclear interaction at short-distances and also support the use of point-like nucleons with two- and three-body effective interactions to describe nuclear systems up to densities several times higher than the central density of atomic nuclei.

    ↳ nucl-exnucl-thNature(2020)·100 citations

Affiliations

first authorsco-authorsvia INSPIRE