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Nuclear Theory·nucl-th

Tuesday·September 20, 2022

13 papers—7 primary·6 cross-listed

All13Primary7Cross-lists6
  1. 01

    [Submitted on 17 Sept 2022]

    Fluctuations of conserved charges in hydrodynamics and molecular dynamics

    Volodymyr Vovchenko🇺🇸

    I present an overview of recent theoretical results on fluctuations of conserved charges in heavy-ion collisions obtained in relativistic hydrodynamics and molecular dynamics frameworks. In particular, I discuss the constraints on the location of the QCD critical point based on comparisons of experimental data on proton number cumulants with precision calculations of non-critical contributions. Recent developments on critical fluctuations in molecular dynamics simulations are covered as well.

    Comments:
    7 pages, 4 figures, contribution to the proceedings of Strangeness in Quark Matter 2022
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2209.08233 [pdf]
    EPJ Web Conf.(2023)·0 citations
  2. 02

    [Submitted on 17 Sept 2022]

    Berry's phase and chiral anomalies

    Kazuo Fujikawa🇯🇵 · Koichiro Umetsu🇯🇵

    The basic materials of Berry's phase and chiral anomalies are presented to appreciate the phenomena related to those notions. As for Berry's phase, a general survey of the subject is presented using both Lagrangian and Hamiltonian formalisms. The canonical Hamiltonian formalism of the Born-Oppenheimer approximation, when applied to the anomalous Hall effect, can incorporate the gauge symmetry of Berry's connection but unable to incorporate the electromagnetic vector potential simultaneously. Transformed to the Lagrangian formalism with a time-derivative term allowed, the Born-Oppenheimer approximation can incorporate the electromagnetic vector potential simultaneously with Berry's connection, but the consistent canonical property is lost and thus becomes classical. The Lagrangian formalism can thus incorporate both gauge symmetries simultaneously but spoils the basic quantum symmetries, and thus results in classical anomalous Poisson brackets and the classical Nernst effect as in the conventional formalism. As for chiral anomalies, we present basic materials by the path integral formulation with an emphasis on fermions on the lattice. A chiral fermion defined by on the lattice does not contain the chiral anomaly for the non-vanishing lattice spacing . The idea of a spectral flow on the lattice does not lead to an anomaly for each species doubler separately but rather to a pair production in a general sense. We also mention that a specific construction called the Ginsparg-Wilson fermion, which is free of species doublers, may practically be useful. We discuss the representative applications of Berry's phase and chiral anomalies in nuclear physics and related fields to illustrate the use of these two basic notions.

    Comments:
    126 pages. 10 figures. Corrected typos and a poorly organized page in Appendix B, together with a new reference
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    2209.08334 [pdf]
    PPNP(2023)·6 citations
  3. 03

    [Submitted on 18 Sept 2022]

    The causality and stability of relativistic spin-hydrodynamics

    Golam Sarwar🇮🇳 · Md Hasanujjaman🇮🇳 · Jitesh R. Bhatt🇮🇳 · Hiranmaya Mishra🇮🇳 · Jan-e Alam🇮🇳

    We study the causality and stability of relativistic hydrodynamics with the inclusion of the spin degree of freedom as a hydrodynamic field. We consider two specific models of spin-hydrodynamics for this purpose. A linear mode analysis for static background shows that a first-order dissipative spin-hydrodynamics remains acausal and admits instabilities. Besides, it is found that the inclusion of the spin field in hydrodynamics leads to new kinds of linear modes in the system. These new modes also exhibit instability and acausal behavior. The second model of the spin-hydrodynamics that we have considered here is equivalent to a particular second-order conventional hydrodynamics with no dissipative effects. For a static background, it is found that the linear modes of this model support the sound waves only. However, when the background has constant vorticity, then the model admits instability and acausality in certain situations. It is found that the spin-dynamics have an effect on the hydrodynamic response of the fluid. These findings point toward the need for a causal and stable theory with spin as a hydrodynamic field to describe the spin-polarized fluid.

    Comments:
    32 pages
    Subjects:
    Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2209.08652 [pdf]
    PRD(2023)·42 citations
  4. 04

    [Submitted on 19 Sept 2022]

    Alpha-particle formation and clustering in nuclei

    E. Khan🇫🇷 · L. Heitz🇫🇷 · F. Mercier🇫🇷 · J.-P. Ebran🇫🇷

    The nucleonic localization function has been used for a decade to study the formation of alpha-particles in nuclei, by providing a measure of having nucleons of a given spin in a single place. However, differences in interpretation remain, compared to the nucleonic density of the nucleus. In order to better understand the respective role of the nucleonic localization function and the densities in the alpha-particle formation in cluster states or in alpha-decay mechanism, both an analytic approximation and microscopic calculations, using energy density functionals, are undertaken. The nucleonic localization function is shown to measure the anti-centrifugal effect, and is not sensitive to the level of compactness of the alpha-particle itself. It probes the purity of the spatial overlap of four nucleons in the four possible (spin, isospin) states. The density provides, in addition, information on the compactness of an alpha-particle cluster. The respective roles of the nucleonic localization function and the density are also analyzed in the case of alpha-particle emission. More generally, criteria to assess the prediction of alpha-cluster in nuclear states are provided.

    Comments:
    9 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.08888 [pdf]
    PRC(2022)·14 citations
  5. 05

    [Submitted on 19 Sept 2022]

    Extracting nuclear matter properties from the neutron star matter equation of state using deep neural networks

    Márcio Ferreira · Valéria Carvalho · Constança Providência

    The extraction of the nuclear matter properties from neutron star (NS) observations is nowadays an important issue, in particular, the properties that characterize the symmetry energy which are essential to describe correctly asymmetric nuclear matter. We use deep neural networks (DNNs) to map the relation between cold -equilibrium NS matter and the nuclear matter properties. Assuming a quadratic dependence on the isospin asymmetry for the energy per particle of homogeneous nuclear matter and using a Taylor expansion up to fourth order in the iso-scalar and iso-vector contributions, we generate a dataset of different realizations of -equilibrium NS matter and the corresponding nuclear matter properties. The DNN model was successfully trained, attaining great accuracy in the test set. Finally, a real case scenario was used to test the DNN model, where a set of 33 nuclear models, obtained within a relativistic mean field approach or a Skyrme force description, were fed into the DNN model and the corresponding nuclear matter parameters recovered with considerable accuracy, in particular, the standard deviations MeV and MeV were obtained, respectively, for the slope of the symmetry energy and the nuclear matter incompressibility at saturation.

    Comments:
    10 pages, 5 figures; published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2209.09085 [pdf]
    PRD(2022)·29 citations
  6. 06

    [Submitted on 19 Sept 2022]

    Nuclear DFT electromagnetic moments in heavy deformed open-shell odd nuclei

    J. Bonnard🇫🇷 · J. Dobaczewski🇬🇧 · G. Danneaux🇫🇮 · M. Kortelainen🇫🇮

    Within the nuclear DFT approach, we determined the magnetic dipole and electric quadrupole moments for paired nuclear states corresponding to the proton (neutron) quasiparticles blocked in the p11/2- (n13/2+) intruder configurations. We performed calculations for all deformed open-shell odd nuclei with 63<=Z<=82 and 82<=N<=126. Time-reversal symmetry was broken in the intrinsic reference frame and self-consistent shape and spin core polarizations were established. We determined spectroscopic moments of angular-momentum-projected wave functions and compared them with available experimental data. We obtained good agreement with data without using effective g-factors or effective charges in the dipole or quadrupole operators, respectively. We also showed that the intrinsic magnetic dipole moments, or those obtained for conserved intrinsic time-reversal symmetry, do not represent viable approximations of the spectroscopic ones.

    Comments:
    22 LaTex pages, 6 figures, Supplemental Material, Physics Letters B, in press
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.09156 [pdf]
    PLB(2023)·24 citations
  7. 07

    [Submitted on 19 Sept 2022]

    dmscatter: A Fast Program for WIMP-Nucleus Scattering

    Oliver Gorton🇺🇸 · Calvin Johnson🇺🇸 · Changfeng Jiao🇺🇸 · Jonathan Nikoleyczik🇺🇸

    Recent work, using an effective field theory framework, has shown the number of possible couplings between nucleons and the dark-matter-candidate Weakly Interacting Massive Particles (WIMPs) is larger than previously thought. Inspired by an existing Mathematica script that computes the target response, we have developed a fast, modern Fortran code, including optional OpenMP parallelization, along with a user-friendly Python wrapper, to swiftly and efficiently explore many scenarios, with output aligned with practices of current dark matter searches. A library of most of the important target nuclides is included; users may also import their own nuclear structure data, in the form of reduced one-body density matrices. The main output is the differential event rate as a function of recoil energy, needed for modeling detector response rates, but intermediate results such as nuclear form factors can be readily accessed.

    Comments:
    15 pages, 6 figures, preprint submitted to Computer Physics Communications, code available at https://github.com/ogorton/dmscatter, version 2 updated with additional references
    Subjects:
    Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2209.09187 [pdf]
    Comput.Phys.Commun.(2023)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE