Nuclear Theory·nucl-th

Monday·May 4, 2020

9 papers—5 primary·4 cross-listed

06
[Submitted on 30 Apr 2020] (cross-list from hep-th)
The Dielectric Skyrme model
C. Adam🇪🇸 · K. Oles🇵🇱 · A. Wereszczynski🇵🇱
We consider a version of the Skyrme model where both the kinetic term and the Skyrme term are multiplied by field-dependent coupling functions. For suitable choices, this "dielectric Skyrme model" has static solutions saturating the pertinent topological bound in the sector of baryon number (or topological charge) $B = \pm 1$ but not for higher $∣ B ∣$ . This implies that higher charge field configurations are unbound, and loosely bound higher skyrmions can be achieved by small deformations of this dielectric Skyrme model. We provide a simple and explicit example for this possibility. Further, we show that the $∣ B ∣ = 1$ BPS sector continues to exist for certain generalizations of the model like, for instance, after its coupling to a specific version of the BPS Skyrme model, i.e., the addition of the sextic term and a particular potential.
Comments:
Latex file, 13 pages, no figures
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2005.00018 [pdf]
PLB(2020)·19 citations
07
[Submitted on 1 May 2020] (cross-list from hep-ph)
Kinetic theory with spin: From massive to massless fermions
Xin-Li Sheng🇨🇳 · Qun Wang🇨🇳 · Xu-Guang Huang🇨🇳
We find that the recently developed kinetic theories with spin for massive and massless fermions are smoothly connected. By introducing a reference-frame vector, we decompose the dipole-moment tensor into electric and magnetic dipole moments. We show that the axial-vector component of the Wigner function contains a contribution from the transverse magnetic dipole moment which accounts for the transverse spin degree of freedom (DOF) and vanishes smoothly in the massless limit. As a result, the kinetic equations, describing four DOF for massive fermions, becomes smoothly the chiral kinetic equations describing two DOF in the massless limit. We also confirm the small-mass behavior of the Wigner function by explicit calculation using a Gaussian wave packet.
Comments:
12 pages, no figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2005.00204 [pdf]
PRD(2020)·31 citations
08
[Submitted on 30 Apr 2020] (cross-list from hep-ph)
Open charm and charmonium states in strong magnetic fields
Amruta Mishra🇮🇳 · S.P.Misra🇮🇳
The mass modifications of the open charm ( $D$ and $D^{*}$ ) mesons, and their effects on the decay widths $D^{*} \to D π$ as well as of the charmonium state, $Ψ (3770)$ to open charm mesons ( $Ψ (3770) \to D D ˉ$ ), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar ( $P$ ) and vector ( $V$ ) mesons ( $D - D^{*}$ , $η_{c}^{'} - Ψ (3770)$ mixings), with the mixing parameter, $g_{P V}$ of a phenomenological three-point ( $P V γ$ ) vertex interaction determined from the observed radiative decay width of $V \to P γ$ . For charged $D - D^{*}$ mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged $D$ and $D^{*}$ mesons modified due to $P V$ mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretic model of composite hadrons with quark (and antiquark) consittuents. The parameter for the charged $D - D^{*}$ mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged $D^{*} \to D π$ as well as $Ψ (3770) \to D^{+} D^{-}$ at large values of the magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm ( $D$ and $D^{*}$ ) mesons as well as of the charmonium states resulting from non-central ultrarelativistic heavy ion collision experiments.
Comments:
25 pages, 3 figures, version to be published in Int. Jour. Mod. Phys. E. arXiv admin note: text overlap with arXiv:2004.01007, arXiv:2006.03478
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2005.00354 [pdf]
IJMPE(2021)·22 citations
09
[Submitted on 1 May 2020] (cross-list from nucl-ex)
Precision measurement of the magnetic octupole moment in $^{45}$ Sc as a test for state-of-the-art atomic- and nuclear-structure theory
R. P. de Groote · J. Moreno · J. Dobaczewski · I. Moore · M. Reponen · B. K. Sahoo · C. Yuan
We report on measurements of the hyperfine $A, B$ and $C$ -constants of the $3 d 4 s^{2}^{2} D_{5/2}$ and $3 d 4 s^{2}^{2} D_{3/2}$ atomic states in $^{45}$ Sc. High-precision atomic calculations of the hyperfine fields of these states and second-order corrections are performed, and are used to extract $C_{5/2} = - 0.06 (6)$ kHz and $C_{3/2} = + 0.04 (3)$ kHz from the data. These results are one order of magnitude more precise than the available literature. From the combined analysis of both atomic states, we infer the nuclear magnetic octupole moment $Ω = - 0.07 (53) μ_{N} b$ , including experimental and atomic structure-related uncertainties. With a single valence proton outside of a magic calcium core, scandium is ideally suited to test a variety of nuclear models, and to investigate in-depth the many intriguing nuclear structure phenomena observed within the neighboring isotopes of calcium. We perform nuclear shell-model calculations of $Ω$ , and furthermore explore the use of Density Functional Theory for evaluating $Ω$ . From this, mutually consistent theoretical values of $Ω$ are obtained, which are in agreement with the experimental value. This confirms atomic structure calculations possess the accuracy and precision required for magnetic octupole moment measurements, and shows that modern nuclear theory is capable of providing meaningful insight into this largely unexplored observable.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2005.00414 [pdf]
PLB(2022)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE

The Dielectric Skyrme model

Kinetic theory with spin: From massive to massless fermions

Open charm and charmonium states in strong magnetic fields

Precision measurement of the magnetic octupole moment in 45Sc as a test for state-of-the-art atomic- and nuclear-structure theory

Affiliations

Precision measurement of the magnetic octupole moment in $^{45}$ Sc as a test for state-of-the-art atomic- and nuclear-structure theory