Nuclear Theory·nucl-th

Tuesday·January 12, 2021

13 papers—7 primary·6 cross-listed

01
[Submitted on 8 Jan 2021]
Implications of PREX-II on the equation of state of neutron-rich matter
Brendan T. Reed🇺🇸 · F. J. Fattoyev🇺🇸 · C. J. Horowitz🇺🇸 · J. Piekarewicz🇺🇸
Laboratory experiments sensitive to the equation of state of neutron rich matter in the vicinity of nuclear saturation density provide the first rung in a "density ladder" that connects terrestrial experiments to astronomical observations. In this context, the neutron skin thickness of 208Pb (Rskin) provides a stringent laboratory constraint on the density dependence of the symmetry energy. In turn, an improved value of Rskin has been reported recently by the PREX collaboration. Exploiting the strong correlation between Rskin and the slope of the symmetry energy L within a specific class of relativistic energy density functionals, we report a value of L=(106 +/- 37)MeV -- that systematically overestimates current limits based on both theoretical approaches and experimental measurements. The impact of such a stiff symmetry energy on some critical neutron-star observables is also examined.
Comments:
5 pages, 4 figures. Manuscript accepted for publication in the Physical Review Letters
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2101.03193 [pdf]
PRL(2021)·574 citations
02
[Submitted on 9 Jan 2021]
NMEs for $0 ν β β (0^{+} \to 2^{+})$ of two-nucleon mechanism for $^{76}$ Ge
Dong-Liang Fang🇨🇳 · Amand Faessler🇩🇪
In this work we present the first beyond closure calculation for the neutrinoless double beta decay ( $0 ν β β$ ) of $^{76}$ Ge to the first $2^{+}$ states of $^{76}$ Se. The isospin symmetry restored Quasi-particle random phase approximation (QRPA) method with the CD-Bonn realistic force is adopted for the nuclear structure calculations. We analyze the structure of the two nucleon mechanism nuclear matrix elements, and estimate the uncertainties from the nuclear many-body calculations. We find $g_{pp}$ plays an important role for the calculations and if quenching is included, suppression for the transition matrix element $M_{λ}$ is found. Our results for the transition matrix elements are about one order of magnitude larger than previous projected Hatree-Fock-Boglyubov results with the closure approximation.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2101.03299 [pdf]
PRC(2021)·9 citations
03
[Submitted on 9 Jan 2021]
Angular Momentum of Fission Fragments from Microscopic Theory
Petar Marević🇺🇸 · Nicolas Schunck🇺🇸 · Jorgen Randrup🇺🇸 · Ramona Vogt🇺🇸
During nuclear fission, a heavy nucleus splits into two rotating fragments. The associated angular momentum is large, yet the mechanism of its generation and its dependence on the mass of fragments remain poorly understood. In this Letter, we provide the first microscopic calculations of angular momentum distributions in fission fragments for a wide range of fragment masses. For the benchmark case of $^{239}$ Pu( $n_{th}$ ,f), we find that the angular momentum of the fragments is largely determined by the nuclear shell structure and deformation, and that the heavy fragments therefore typically carry less angular momentum than their light partners. We use the fission model $FREYA$ to simulate the emission of neutrons and photons from the fragments. The dependence of the angular momenta on fragment mass after the emission of neutrons and statistical photons is linear for the heavy fragments and either constant or weakly linear for the light fragments, consistent with the universal sawtooth pattern suggested by recent experimental data. Finally, we observe that using microscopic angular momentum distributions modifies the number of emitted photons significantly.
Comments:
7 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.03406 [pdf]
PRC(2021)·53 citations
04
[Submitted on 10 Jan 2021]
Fission fragment mass yields of Th to Rf even-even nuclei
Krzysztof Pomorski · Jose M. Blanco · Pavel V. Kostryukov · Artur Dobrowolski · Bozena Nerlo-Pomorska · Michal Warda · Zhigang Xiao · Yongjing Chen · Lile Liu · Jun-Long Tian · Xinyue Diao · Qianghua Wu
Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass-yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass-yields of considered nuclei are evaluated within a 3D collective model using the Born-Oppenheimer approximation.
Comments:
11 pages, 12 figures, submitted to the Chinese Physics C. arXiv admin note: text overlap with arXiv:2001.08652
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.03527 [pdf]
CPC(2021)·16 citations
05
[Submitted on 11 Jan 2021]
$Δ$ -admixed neutron stars: spinodal instabilities and dUrca processes
Adriana R. Raduta🇷🇴
Within the covariant density functional theory of nuclear matter we build equations of state of $Δ$ -admixed compact stars. Uncertainties in the interaction of $Δ (1232)$ resonance states with nuclear matter, due to lack of experimental data, are accounted for by varying the coupling constants to scalar and vector mesonic fields. We find that, over a wide range of the parameter space allowed by nuclear physics experiments and astrophysical observations, cold catalyzed star matter exhibits a first order phase transition which persists also at finite temperature and out of $β$ -equilibrium in the neutrino-transparent matter. Compact stars featuring such a phase transition in the outer core have small radii and, implicitly, tidal deformabilities. The parameter space is identified where simultaneously $Δ$ -admixed compact stars obey the astrophysical constraint on maximum mass and allow for dUrca processes, which is otherwise forbidden.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2101.03718 [pdf]
PLB(2021)·42 citations
06
[Submitted on 11 Jan 2021]
Nuclear reactions in artificial traps
Peng Guo🇨🇳 · Bingwei Long🇨🇳
Coupled-channel two-particle systems bound by a harmonic trap are discussed in the present paper. We derive the formula that relates the energy levels of such trapped systems to phase shifts and inelasticity of coupled-channel reactions. The formula makes it possible to extract amplitudes of inelastic nuclear reactions from ab initio calculations of discrete levels of many-nucleon systems in a harmonic trap.
Comments:
7 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2101.03901 [pdf]
J.Phys.G(2022)·25 citations
07
[Submitted on 11 Jan 2021]
Quark matter contribution to the heat capacity of magnetized neutron stars
E. J. Ferrer🇺🇸 · V. de la Incera🇺🇸 · P. Sanson🇺🇸
In this paper, we find the heat capacity of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and use it to explore the feasibility of this phase for a neutron star interior. MDCDW is a spatially inhomogeneous phase of quark matter known to be favored at intermediate densities over the chirally symmetric phase and the color-flavor-locked superconducting phase. By comparing our result to the lower limit of the core heat capacity established from observations of transiently accreting neutron stars, we show that the heat capacity of MDCDW quark matter is well above that lower limit and hence cannot be ruled out. This result adds to a wealth of complementary investigations, all of which has served to strengthen the viability of a neutron star interior made of MDCDW quark matter. For completeness, we review the contributions to the heat capacity of the main neutron star ingredients at low, high and intermediate densities, with and without the presence of a magnetic field.
Comments:
To appear in PRD
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2101.04032 [pdf]
PRD(2021)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Implications of PREX-II on the equation of state of neutron-rich matter

NMEs for 0νββ(0+→2+) of two-nucleon mechanism for 76Ge

Angular Momentum of Fission Fragments from Microscopic Theory

Fission fragment mass yields of Th to Rf even-even nuclei

Δ-admixed neutron stars: spinodal instabilities and dUrca processes

Nuclear reactions in artificial traps

Quark matter contribution to the heat capacity of magnetized neutron stars

Affiliations

NMEs for $0 ν β β (0^{+} \to 2^{+})$ of two-nucleon mechanism for $^{76}$ Ge

$Δ$ -admixed neutron stars: spinodal instabilities and dUrca processes