PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·October 22, 2020

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    [Submitted on 20 Oct 2020]

    Hadron-Quark Phase Transition at Finite Density in the Presence of a Magnetic Field: Anisotropic Approach

    E. J. Ferrer🇺🇸 · A. Hackebill🇺🇸

    We investigate the hadron-quark phase transition at finite density in the presence of a magnetic field taking into account the anisotropy created by a uniform magnetic field in the system's equations of state. We find a new anisotropic equilibrium condition that will drive the first-order phase transition along the boundary between the two phases. Fixing the magnetic field in the hadronic phase, the phase transition is realized by increasing the baryonic chemical potential at zero temperature. It is shown that the magnetic field is mildly boosted after the system transitions from the hadronic to the quark phase. The magnetic-field discontinuity between the two phases is supported by a surface density of magnetic monopoles, which accumulate at the boundary separating the two phases. The mechanism responsible for the monopole charge density generation is discussed. Each phase is found to be paramagnetic with higher magnetic susceptibility in the quark phase. The connection with the physics of neutron stars is highlighted through out the paper.

    Comments:
    30 pages and 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2010.10574 [pdf]
    Int.J.Mod.Phys.A(2022)·16 citations
  2. 02

    [Submitted on 20 Oct 2020]

    Windowed multipole representation of R-matrix cross sections

    Pablo Ducru · Vladimir Sobes · Abdulla Alhajri · Isaac Meyer · Benoit Forget · Colin Josey · Jingang Liang

    Nuclear cross sections are basic inputs to any nuclear computation. Campaigns of experiments are fitted with the parametric R-matrix model of quantum nuclear interactions, and the resulting cross sections are documented - both point-wise and as resonance parameters (with uncertainties) - in standard evaluated nuclear data libraries (ENDF, JEFF, BROND, JENDL, CENDL, TENDL): these constitute our common knowledge of fundamental nuclear physics. In the past decade, a collaborative effort has been deployed to establish a new nuclear cross section library format - the Windowed Multipole Library - with the goal of considerably reducing the cost of cross section calculations in nuclear transport simulations. This article lays the theoretical foundations underpinning these efforts. From general R-matrix scattering theory, we derive the windowed multipole representation of nuclear cross sections. Though physically and mathematically equivalent, the windowed multipole representation is particularly well suited for subsequent temperature treatment of angle-integrated cross sections: we show that accurate Doppler broadening can be performed analytically up to the first reaction threshold; and we derive cross sections temperature derivatives to any order. Furthermore, we here establish a way of converting the R-matrix resonance parameters uncertainty (covariance matrices) into windowed multipole parameters uncertainty. We show that generating stochastic nuclear cross sections by sampling from the resulting windowed multipole covariance matrix can reproduce the cross section uncertainty in the original nuclear data file. Through this foundational article, we hope to make the Windowed Multipole Representation accessible, reproducible, and usable for the nuclear physics community, as well as provide the theoretical basis for future research on expanding its capabilities.

    Comments:
    35 pages, 6 figues, 3 tables, article in review at Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2010.10585 [pdf]
    PRC(2021)·6 citations
  3. 03

    [Submitted on 21 Oct 2020]

    Properties of dibaryons in nuclear medium

    M. Kakenov🇷🇺 · V.I. Kukulin🇷🇺 · V.N. Pomerantsev🇷🇺 · O. Bayakhmetov🇰🇿

    Properties of six-quark dibaryons in nuclear medium are considered by example of nuclei within the three-cluster model. Dibaryon production in nuclei leads to the appearance of a three-body force between the dibaryon and nuclear core. This non-conventional scalar force is shown to provide an additional attractive contribution to the three-body binding energy. This three-body contribution improves noticeably agreement between theoretical results and experimental data for the majority of observables. The most serious difference between the traditional -force models and the dibaryon-induced model is found for the nucleon momentum distribution, the latter model providing a strong enrichment of the high-momentum components both for Li and He cases.

    Comments:
    19 pages, 13 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2010.10857 [pdf]
    EPJA(2020)·3 citations
  4. 04

    [Submitted on 20 Oct 2020]

    Euclidean formulation of relativistic quantum mechanics of N particles

    Gohin Shaikh Samad🇺🇸 · W.N.Polyzou🇺🇸

    A Euclidean formulation of relativistic quantum mechanics for systems of a finite number of degrees of freedom is discussed. Relativistic treatments of quantum theory are needed to study hadronic systems at sub-hadronic distance scales. While direct interaction approaches to relativistic quantum mechanics have proved to be useful, they have two disadvantages. One is that cluster properties are difficult to realize for systems of more than two particles. The second is that the relation to quantum field theories is indirect. Euclidean formulations of relativistic quantum mechanics provide an alternative representation that does not have these difficulties. More surprising, the theory can be formulated entirely in the Euclidean representation without the need for analytic continuation. In this work a Euclidean representation of a relativistic -particle system is discussed. Kernels for systems of N free particles of any spin are given and shown to be reflection positive. Explicit formulas for generators of the Poincaré group for any spin are constructed and shown to be self-adjoint on the Euclidean representation of the Hilbert space. The structure of correlations that preserve both the Euclidean covariance and reflection positivity is discussed.

    Comments:
    29 pages. arXiv admin note: substantial text overlap with arXiv:1906.10083
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th); Quantum Physics (quant-ph)
    arXiv:
    2010.10944 [pdf]
    PRC(2021)·3 citations
  5. 05

    [Submitted on 21 Oct 2020]

    SU(3) partial dynamical symmetry and nuclear shapes

    A. Leviatan

    We consider several variants of SU(3) partial dynamical symmetry in relation to quadrupole shapes in nuclei. Explicit construction of Hamiltonians with such property is presented in the framework of the interacting boson model (IBM), including higher order terms, and in its proton-neutron extension (IBM-2). The cases considered include a single prolate-deformed shape with solvable ground and or bands, coexisting prolate-oblate shapes with solvable ground bands, and aligned axially-deformed proton-neutron shapes with solvable symmetric ground and bands and mixed-symmetry scissors and bands.

    Comments:
    21 pages, 8 figures, 2 Tables, invited article for EPJ ST Special Issue: Role of Symmetries in Nuclear Physics
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2010.10951 [pdf]
    Eur.Phys.J.ST(2020)·3 citations
  6. 06

    [Submitted on 21 Oct 2020]

    Dispersive evaluation of the Lamb shift in muonic deuterium from chiral effective field theory

    Bijaya Acharya🇩🇪 · Vadim Lensky🇩🇪 · Sonia Bacca🇩🇪 · Mikhail Gorchtein🇩🇪 · Marc Vanderhaeghen🇩🇪

    We merge the dispersive relation approach and the ab initio method to compute nuclear structure corrections to the Lamb shift in muonic deuterium. We calculate the deuteron response functions and corresponding uncertainties up to next-to-next-to-next-to-leading order in chiral effective field theory and compare our results to selected electromagnetic data to test the validity of the theory. We then feed response functions calculated over a wide range of kinematics to the dispersion-theory formalism and show that an improved accuracy is obtained compared to that with the use of available experimental data in the dispersive analysis. This opens up the possibility of applying this hybrid method to other light muonic atoms and supplementing experimental data with ab initio theory for kinematics where data are scarce or difficult to measure with the goal of reducing uncertainties in estimates of nuclear structure effects in atomic spectroscopy.

    Comments:
    17 pages, 4 figures; published version
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2010.11155 [pdf]
    PRC(2021)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE