Nuclear Theory·nucl-th

Friday·November 12, 2021

6 papers—4 primary·2 cross-listed

01
Prediction of the excitation energies of the 2 $_{1}^{+}$ states for superheavy nuclei based on the microscopically derived Grodzins relation
N.Yu. Shirikova · A.V. Sushkov · L.A. Malov · E.A. Kolganova · R.V. Jolos
As the result of synthesis of nuclei with large proton numbers a new region of investigations of the structure of nuclei has been discovered. Due to the recent significant increase in the yield of superheavy nuclei their gamma-spectroscopic studies became possible. The purpose of paper is to predict the excitation energies of the $2_{1}^{+}$ states of nuclei with Z $\geq 100$ using the microscopic variant of the Grodzins relation derived based on the geometrical collective model. The excitation energies of the $2_{1}^{+}$ states of the even-even nuclei from $^{256}$ Fm to $_{120}^{296}$ X which differ from each other in the number of $α$ -particles are predicted. It is shown that at the beginning of the chain of the studied nuclei the excitation energies of the $2_{1}^{+}$ states don't exceed 100 keV. Then $E (2_{1}^{+})$ sharply increases with $A$ and reaches maximum value of $400 - 500$ keV in $^{284}$ Fl or $^{292}$ Og.
nucl-thPRC(2022)·6 citations
02
Fixed-Point Few-Body Hamiltonians in Quantum Mechanics
Lauro Tomio🇧🇷 · Tobias Frederico🇧🇷 · Varese S. Timóteo🇧🇷 · Marcelo T. Yamashita🇧🇷
We revisited how Weinberg's ideas in Nuclear Physics influenced our own work and lead to a renormalization group invariant framework within the quantum mechanical few-body problem, and we also update the discussion on the relevant scales in the limit of short-range interactions. In this context, it is revised the formulation of the subtracted scattering equations and fixed-point Hamiltonians applied to few-body systems, in which the original interaction contains point-like singularities, such as Dirac-delta and/or its derivatives. The approach is being illustrated by considering two-nucleons described by singular interactions. This revision also includes an extension of the renormalization formalism to three-body systems, which is followed by an updated discussion on the applications to four particles.
nucl-thquant-phFew Body Syst.(2022)·0 citations
03
Neutron star properties with careful parameterization in the (axial)vector meson extended linear sigma model
Péter Kovács🇭🇺 · János Takátsy🇭🇺 · Jürgen Schaffner-Bielich🇩🇪 · György Wolf🇭🇺
The existence of quark matter inside the cores of heavy neutron stars is a possibility which can be probed with modern astrophysical observations. We use an (axial)vector meson extended quark-meson model to describe quark matter in the core of neutron stars. We discover that an additional parameter constraint is necessary in the quark model to ensure chiral restoration at high densities. By investigating hybrid star sequences with various parameter sets we show that low sigma meson masses are needed to fulfill the upper radius constraints, and that the maximum mass of stable hybrid stars is only slightly dependent on the parameters of the crossover-type phase transition. Using this observation and results from recent astrophysical measurements a constraint of 2.6 < g_V < 4.3 is set for the constituent quark - vector meson coupling. The effect of a nonzero bag constant is also investigated and we observe that its effect is small for values adopted in previous works.
nucl-thhep-phPRD(2022)·22 citations
04
A modified Brink-Axel hypothesis for astrophysical Gamow-Teller transitions
Raul A. Herrera · Calvin W. Johnson · George M. Fuller
Weak interaction charged current transition strengths from highly excited nuclear states are fundamental ingredients for accurate modeling of compact object composition and dynamics, but are difficult to obtain either from experiment or theory. For lack of alternatives, calculations have often fallen back upon a generalized Brink-Axel hypothesis, that is, assuming the strength function (transition probability) is independent of the initial nuclear state but depends only upon the transition energy and the weak interaction properties of the parent nucleus ground state. Here we present numerical evidence for a modified `local' Brink-Axel hypothesis for Gamow-Teller transitions for $p f$ -shell nuclei relevant to astrophysical applications. Specifically, while the original Brink-Axel hypothesis does not hold globally, strength functions from initial states nearby in energy are similar within statistical fluctuations. This agrees with previous work on strength function moments. Using this modified hypothesis, we can tackle strength functions at previously intractable initial energies, using semi-converged initial states at arbitrary excitation energy. Our work provides a well-founded method for computing accurate thermal weak transition rates for medium-mass nuclei at temperatures occurring in stellar cores near collapse. We finish by comparing to previous calculations of astrophysical rates.
nucl-thastro-ph.SRphysics.comp-phPRC(2022)·7 citations
05
Finite volume and magnetic field effects on the two-pion correlation function in relativistic heavy-ion collisions
Alejandro Ayala🇲🇽 · Santiago Bernal-Langarica🇲🇽 · Cristian Villavicencio🇨🇱
We study the combined effects of a finite volume and an external magnetic field on the charged two-pion correlation function. For these purposes, we consider a dilute system of pions where the finite volume effects are introduced computing the pion wave functions with rigid boundary conditions in a cylindrical geometry in the presence of a uniform and constant magnetic field. We find that for slow pions, namely, for the case where the average pair momentum is small, the correlation function shows a large distortion, as opposed to the case where the average pair momentum is large. For a finite density system, the intercept of the correlation function is reduced, signaling the increasing importance of the pion ground state contribution. An increasing strength of the magnetic field reduces the importance of the ground state and the intercept becomes closer to 2.
↳ hep-phnucl-thPRD(2022)·3 citations
06
The Second Love Number of Dark Compact Planets and Neutron Stars with Dark Matter
Yannick Dengler🇩🇪 · Jürgen Schaffner-Bielich🇩🇪 · Laura Tolos🇪🇸
We study the mass-radius relation and the second Love number of compact objects made of ordinary matter and non-selfannihilating fermionic dark matter for a wide range of dark matter particle masses, and for the cases of weakly and strongly interacting dark matter. We obtain stable configurations of compact objects with radii smaller than 10 km and masses similar to Earth- or Jupiter-like stellar objects. In certain parameter ranges we find second Love numbers which are markedly different compared to those expected for neutron stars without dark matter. Thus, by obtaining the compactness of these compact objects and measuring their tidal deformability from gravitational wave detections from binary neutron star mergers, the extracted value of second Love number would allow to determine the existence of dark matter inside neutron stars irrespective of the equation of state of ordinary matter.
↳ astro-ph.HEnucl-thPRD(2022)·77 citations

Affiliations

first authorsco-authorsvia INSPIRE

Prediction of the excitation energies of the 21+​ states for superheavy nuclei based on the microscopically derived Grodzins relation

Fixed-Point Few-Body Hamiltonians in Quantum Mechanics

Neutron star properties with careful parameterization in the (axial)vector meson extended linear sigma model

A modified Brink-Axel hypothesis for astrophysical Gamow-Teller transitions

Finite volume and magnetic field effects on the two-pion correlation function in relativistic heavy-ion collisions

The Second Love Number of Dark Compact Planets and Neutron Stars with Dark Matter

Affiliations

Prediction of the excitation energies of the 2 $_{1}^{+}$ states for superheavy nuclei based on the microscopically derived Grodzins relation