Nuclear Theory·nucl-th

Wednesday·March 27, 2024

11 papers—7 primary·4 cross-listed

01
Dark matter effects on the properties of neutron stars: compactness and tidal deformability
Hong-Ming Liu🇨🇳 · Jin-Biao Wei🇨🇳 · Zeng-Hua Li🇨🇳 · G. F. Burgio🇮🇹 · H. C. Das🇮🇹 · H.-J. Schulze🇮🇹
We systematically study the observable properties of dark-matter admixed neutron stars, employing a realistic nuclear EOS in combination with self-interacting fermionic dark matter respecting constraints on the self-interaction cross section. Deviations from universal relations valid for nucleonic neutron stars are analyzed over the whole parameter space of the model and unequivocal signals for the presence of dark matter in neutron stars are identified.
nucl-thPRD(2024)·45 citations
02
Axion-Polaritons in quark stars: a possible solution to the missing pulsar problem
E. J. Ferrer🇺🇸 · V. de la Incera🇺🇸
This paper proposes an alternative mechanism to solve the so-called missing pulsar problem, a standing paradox between the theoretical expectations about the number of pulsars that should exist in the galaxy center of the Milky Way and their absence in the observations. The mechanism is based on the transformation of incident $γ$ rays into hybridized modes, known as axion-polaritons, which can exist inside highly magnetized quark stars with a quark matter phase known as the magnetic dual chiral density wave phase. This phase, which is favored over several other dense matter phases candidates at densities a few times nuclear saturation density, has already passed several important astrophysical tests. In the proposed mechanism, the absence of young magnetars occurs because as electromagnetic waves inside the star can only propagate through the hybridized modes, incident photons coming from a $γ$ -ray burst get transformed into massless and massive axion polaritons by the Primakoff effect. Once thermalized, the massive axion-polaritons can self-gravitate up to a situation where their total mass overpasses the Chandrasekhar limit for these bosons, producing a mini blackhole that collapses the star.
nucl-thEPJC(2024)·7 citations
03
Competition between allowed and first-forbidden $β$ decay in $r$ -process waiting-point nuclei within a relativistic beyond-mean-field approach
Caroline E. P. Robin · Gabriel Martínez-Pinedo
We compute $β$ -decay half-lives of isotonic nuclear chains located at neutron shell closures $N = 50$ , $82$ , $126$ and $184$ , which are of particular importance for the $r$ -process nucleosynthesis, and study the role of first-forbidden transitions in a framework that includes complex nucleonic correlations beyond the quasiparticle random phase approximation. Such correlations are accounted for by coupling single nucleons to collective degrees of freedom (nuclear vibrations), and are found essential to reproduce available experimental $β$ -decay rates and more precise many-body methods. We find that the nucleon-vibration correlations tend to decrease the probability of decay via first-forbidden transition near stability, as they enhance Gamow-Teller transitions at low energy. While in the lighter systems allowed transitions dominate, the decay of $N = 126$ and $N = 184$ nuclei is found to occur to a large extent via first-forbidden transitions, and in particular those induced by $1^{-}$ and $0^{-}$ operators. Overall the many-body method based on nucleon-vibration coupling provides an ideal framework for future large-scale calculations. Upcoming experimental measurements of $β$ -decay rates in the $N = 126$ region by radioactive-beam facilities will be crucial in order to validate the approach.
nucl-thnucl-exPRC(2024)·10 citations
04
Time-dependent nuclear energy-density functional theory toolkit for neutron star crust: Dynamics of a nucleus in a neutron superfluid
Daniel Pȩcak · Agata Zdanowicz · Nicolas Chamel · Piotr Magierski · Gabriel Wlazłowski
We present a new numerical tool designed to probe the dense layers of neutron star crusts. It is based on the time-dependent Hartree-Fock-Bogoliubov theory with generalized Skyrme nuclear energy-density functionals of the Brussels-Montreal family. We use it to study the time evolution of a nucleus accelerating through superfluid neutron medium in the inner crust of a neutron star. We extract an effective mass in the low velocity limit. We observe a threshold velocity and specify mechanisms of dissipation: phonon emission, Cooper pairs breaking, and vortex rings creation. These microscopic effects are of key importance for understanding various neutron star phenomena. Moreover, the mechanisms we describe are general and apply also to other fermionic superfluids interacting with obstacles like liquid helium or ultracold gases.
nucl-thastro-ph.HEcond-mat.supr-conPRX(2024)·17 citations
05
Determination of nuclear matter radii by means of microscopic optical potentials: the case of $^{78}$ Kr
Matteo Vorabbi · Paolo Finelli · Carlotta Giusti
In this work we use microscopic Nucleon-Nucleus Optical Potentials (OP) to analyze elastic scattering data for the differential cross section of the $^{78}$ Kr (p,p) $^{78}$ Kr reaction, with the goal of extracting the matter radius and estimating the neutron skin, quantities that are both needed to determine the slope parameter $L$ of the nuclear symmetry energy. Our analysis is performed with the factorized version of the microscopic OP obtained in a previous series of papers within the Watson multiple scattering theory at the first order of the spectator expansion, which is based on the underlying nucleon-nucleon dynamics and is free from phenomenological inputs. Differently from our previous applications, the proton and neutron densities are described with a two-parameter Fermi (2pF) distribution, which makes the extraction of the matter radius easier and allows us to make a meaningful comparison with the original analysis, that was performed with the Glauber model. With standard minimization techniques we performed data analysis and extracted the matter radius and the neutron skin. Our analysis produces a matter radius of $R_{m}^{(rms)} = 4.12$ fm, in good agreement with previous matter radii extracted from $^{76}$ Kr and $^{80}$ Kr, and a neutron skin of $Δ R_{n p} ≃ - 0.1$ fm, compatible with a previous analysis. Our factorized microscopic OP, supplied with 2pF densities, is a valuable tool to perform the analysis of the experimental differential cross section and extract information such as matter radius and neutron skin. Without any free parameters it provides a reasonably good description of the experimental differential cross section for scattering angles up to $\approx$ 40 degrees. Compared to the Glauber model our OP can be applied to a wider range of scattering angles and allows one to probe the nuclear systems in a more internal region.
nucl-thFew Body Syst.(2024)·0 citations
06
Nuclear matrix elements of neutrinoless double-beta decay in covariant density functional theory with different mechanisms
C. R. Ding · Gang Li · J. M. Yao
Nuclear matrix elements (NMEs) for neutrinoless double-beta ( $0 ν β β$ ) decay in candidate nuclei play a crucial role in interpreting results from current experiments and in designing future ones. Accurate NME values serve as important nuclear inputs for constraining parameters in new physics, such as neutrino mass and the Wilson coefficients of lepton-number-violating (LNV) operators. In this study, we present a comprehensive calculation of NMEs for $0 ν β β$ decay in $^{76}$ Ge, $^{82}$ Se, $^{100}$ Mo, $^{130}$ Te, and $^{136}$ Xe, using nuclear wave functions obtained from multi-reference covariant density functional theory (MR-CDFT). We employ three types of transition potentials at the leading order in chiral effective field theory. Our results, along with recent data, are utilized to constrain the coefficients of LNV operators. The results demonstrate that the combined NMEs based on the Feynman diagrams at the hadronic scale for the nonstandard mechanisms lead to uncertainty by different nuclear models comparable to that for the standard mechanism. The use of NMEs from various nuclear models does not dramatically change the parameter space intervals for the coefficients, although MR-CDFT yields the most stringent constraint. Furthermore, our NMEs can also be used to perform a more comprehensive analysis with multiple isotopes.
nucl-thhep-phnucl-exPLB(2024)·7 citations
07
Synthesis of superheavy elements in the outer crust of a magnetar
Davide Basilico · Xavier Roca-Maza · Gianluca Colò
A theoretical understanding of a possible mechanism for synthesizing superheavy elements in the outer crust of magnetars is presented. We demonstrate that such a mechanism can be present whenever the baryon density in the outer crust of a neutron star reaches values around $1 0^{- 2}$ fm $^{- 3}$ . This scenario could be realized in magnetars with hypothetical large magnetic fields, $B \geq 1 0^{18}$ G. Under such conditions, the Coulomb lattice, formed by ionized nuclei, enables a mechanism that synthesizes superheavy elements.
nucl-thPRC(2025)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Dark matter effects on the properties of neutron stars: compactness and tidal deformability

Axion-Polaritons in quark stars: a possible solution to the missing pulsar problem

Competition between allowed and first-forbidden β decay in r-process waiting-point nuclei within a relativistic beyond-mean-field approach

Time-dependent nuclear energy-density functional theory toolkit for neutron star crust: Dynamics of a nucleus in a neutron superfluid

Determination of nuclear matter radii by means of microscopic optical potentials: the case of 78Kr

Nuclear matrix elements of neutrinoless double-beta decay in covariant density functional theory with different mechanisms

Synthesis of superheavy elements in the outer crust of a magnetar

Affiliations

Competition between allowed and first-forbidden $β$ decay in $r$ -process waiting-point nuclei within a relativistic beyond-mean-field approach

Determination of nuclear matter radii by means of microscopic optical potentials: the case of $^{78}$ Kr