Nuclear Theory·nucl-th

Tuesday·September 21, 2021

14 papers—7 primary·7 cross-listed

08
Nucleon Structure and Strong Interactions in Dark Matter Capture in Neutron Stars
Nicole F. Bell🇦🇺 · Giorgio Busoni🇩🇪 · Theo F. Motta🇦🇺 · Sandra Robles🇦🇺 · Anthony W. Thomas🇦🇺 · Michael Virgato🇦🇺
We outline two important effects that are missing from most evaluations of the dark matter capture rate in neutron stars. As dark matter scattering with nucleons in the star involves large momentum transfer, nucleon structure must be taken into account via a momentum dependence of the hadronic form factors. In addition, due to the high density of neutron star matter, we should account for nucleon interactions rather than modeling the nucleons as an ideal Fermi gas. Properly incorporating these effects is found to suppress the dark matter capture rate by up to four orders of magnitude for the heaviest stars.
↳ hep-phastro-ph.COastro-ph.HEnucl-thPRL(2021)·98 citations
09
Pauli radius of the proton
Zhu-Fang Cui🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪
Using a procedure based on interpolation via continued fractions supplemented by statistical sampling, we analyse proton magnetic form factor data obtained via electron+proton scattering on $Q^{2} \in [0.027, 0.55]$ GeV $^{2}$ with the goal of determining the proton magnetic radius. The approach avoids assumptions about the function form used for data interpolation and ensuing extrapolation onto $Q^{2} ≃ 0$ for extraction of the form factor slope. In this way, we find $r_{M} = 0.817 (27)$ fm. Regarding the difference between proton electric and magnetic radii calculated in this way, extant data are seen to be compatible with the possibility that the slopes of the proton Dirac and Pauli form factors, $F_{1, 2} (Q^{2})$ , are not truly independent observables; to wit, the difference $F_{1}^{'} (0) - F_{2}^{'} (0) / κ_{p} = [1 + κ_{p}] / [4 m_{p}^{2}]$ , viz. the proton Foldy term.
↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2021)·11 citations
10
$F t$ values of the mirror $β$ transitions and the weak magnetism induced current in allowed nuclear $β$ decay
N. Severijns🇧🇪 · L. Hayen🇧🇪 · V. De Leebeeck🇧🇪 · S. Vanlangendonck🇧🇪 · K. Bodek🇵🇱 · D. Rozpedzik🇵🇱 · I.S. Towner🇺🇸
In recent years a number of correlation measurements in nuclear $β$ decay have been performed reaching a precision of the order of 1\% and below and it is expected that even higher precision will be reached in the near future. At these levels of precision higher-order corrections due to e.g. recoil terms induced by the strong interaction and radiative corrections cannot necessarily be neglected anymore when interpreting these results in terms of new physics or extracting a value for the $V_{u d}$ quark-mixing matrix element. We provide here an update of the $F t$ values of the $T = 1/2$ mirror $β$ decays as well as an overview of current experimental and theoretical knowledge of the most important recoil term, weak magnetism, for both the $T = 1/2$ mirror $β$ transitions and a large set of $β$ decays in higher isospin multiplets. The matrix elements determining weak magnetism were calculated in the nuclear shell model and cross-checked against experimental data, showing overall good agreement. Additionally, we show that further insight can be obtained from properly deformed nuclear potentials, in particular for mirror $T = 1/2$ decays.. The results provide new insights in the size of weak magnetism, extending the available information to $β$ transitions of nuclei with masses up to $A =$ 75. This provides important guidance for the planning and interpretation of ongoing and new precise correlation measurements in nuclear $β$ decay searching for new physics or to extract the $V_{u d}$ quark-mixing matrix element in mirror $β$ decays. This more detailed knowledge of weak magnetism can also be of interest for further theoretical work related to the reactor neutrino problem.
↳ nucl-exnucl-thPRC(2023)·28 citations
11
Spectral splits and entanglement entropy in collective neutrino oscillations
Amol V. Patwardhan🇺🇸 · Michael J. Cervia🇺🇸 · A. B. Balantekin🇺🇸
In environments such as core-collapse supernovae, neutron star mergers, or the early universe, where the neutrino fluxes can be extremely high, neutrino-neutrino interactions are appreciable and contribute substantially to their flavor evolution. Such a system of interacting neutrinos can be regarded as a quantum many-body system, and prospects for nontrivial quantum correlations, i.e., entanglement, developing in a gas of interacting neutrinos have been investigated previously. In this work, we uncover an intriguing connection between the entropy of entanglement of individual neutrinos with the rest of the ensemble, and the occurrence of spectral splits in the energy spectra of these neutrinos, which develop as a result of collective neutrino oscillations. In particular, for various types of neutrino spectra, we demonstrate that the entanglement entropy is highest for the neutrinos whose locations in the energy spectrum are closest to the spectral split(s). This trend demonstrates that the quantum entanglement is strongest among the neutrinos that are close to these splits, a behavior that seems to persist even as the size of the many-body system is increased.
↳ hep-phastro-ph.HEnucl-thquant-phPRD(2021)·63 citations
12
Mesons and Baryons: Parity Partners
L.X. Gutiérrez-Guerrero🇲🇽 · G. Paredes-Torres🇲🇽 · A. Bashir🇲🇽
We calculate masses of light and heavy mesons as well as baryons of negative parity containing $u, d, s, c$ and $b$ quarks. It is an extension of our previous work where we had studied the positive parity baryons. We adopt a quark-diquark picture of baryons where the diquarks are non-pointlike with a finite spatial extension. The mathematical foundation for this analysis is implemented through a symmetry-preserving Schwinger-Dyson equations treatment of a vector-vector contact interaction, which preserves key features of quantum chromodynamics, such as confinement, chiral symmetry breaking, axial vector Ward-Takahashi identity and low-energy Goldberger-Treiman relations. This treatment simultaneously describes mesons and provides attractive correlations for diquarks in the $3$ representation. Employing this model, we compute the spectrum and masses of all spin-1/2 and spin-3/2 baryons of negative parity, supplementing our earlier evaluation of positive parity baryons, containing 1, 2 or 3 heavy quarks. In the process, we calculate masses of a multitude of mesons and corresponding diquarks. Wherever possible, we make comparisons of our results with known experimental observations as well as theoretical predictions of several models and approaches including lattice quantum chromodynamics, finding satisfactory agreement. We also make predictions for heavier states not yet observed in the experiment.
↳ hep-phnucl-thPRD(2021)·37 citations
13
$r$ -process nucleosynthesis from compact binary mergers
Albino Perego🇮🇹 · Friedrich-Karl Thielemann🇨🇭 · Gabriele Cescutti🇮🇹
The merger of two neutron stars or of a neutron star and a black hole often result in the ejection of a few percents of a solar mass of matter expanding at high speed in space. Being matter coming from the violent disruption of a neutron star, these ejecta are initially very dense, hot and extremely rich in neutrons. The few available protons form heavy nuclei ("seeds") that absorb the more abundant free neutrons, increasing their size. The neutron density is so high that a substantial number of neutron captures occur before the resulting unstable nuclei can decay toward more stable configurations, converting neutrons into protons. Depending mostly on the initial neutron richness, this mechanism leads to the formation of up to half of the heavy elements that we observe in nature and it is called rapid neutron capture process (" $r$ -process"). The prediction of the precise composition of the ejecta requires a detailed knowledge of the properties of very exotic nuclei, that have never been produced in a laboratory. Despite having long been a speculative scenario, nowadays several observational evidences point to compact binary mergers as one of the major sites where heavy elements are formed in the Universe. The most striking one was the detection of a kilonova following the merger of a neutron star binary: the light emitted by this astronomical transient is indeed powered by the radioactive decay of freshly synthesized neutron-rich nuclei and testifies the actual nature of compact binary mergers as cosmic forges.
↳ astro-ph.HEgr-qcnucl-th20 citations
14
The nuclear matter density functional under the nucleonic hypothesis
Hoa Dinh Thi🇫🇷 · Chiranjib Mondal🇫🇷 · Francesca Gulminelli🇫🇷
A Bayesian analysis of the possible behaviors of the dense matter equation of state informed through recent LIGO-Virgo as well as NICER measurements reveals that all the present observations are compatible with a fully nucleonic hypothesis for the composition of dense matter, even in the core of the most massive pulsar PSR J0740+6620. Under the hypothesis of a nucleonic composition, we extract the most general behavior of the energy per particle of symmetric matter and density dependence of the symmetry energy, compatible with the astrophysical observations as well as our present knowledge of low energy nuclear physics from effective field theory predictions and experimental nuclear mass data. These results can be used as a null hypothesis to be confronted with future constraints on dense matter to search for possible exotic degrees of freedom.
↳ astro-ph.HEnucl-thUniverse(2021)·52 citations

Affiliations

first authorsco-authorsvia INSPIRE

Nucleon Structure and Strong Interactions in Dark Matter Capture in Neutron Stars

Pauli radius of the proton

Ft values of the mirror β transitions and the weak magnetism induced current in allowed nuclear β decay

Spectral splits and entanglement entropy in collective neutrino oscillations

Mesons and Baryons: Parity Partners

r-process nucleosynthesis from compact binary mergers

The nuclear matter density functional under the nucleonic hypothesis

Affiliations

$F t$ values of the mirror $β$ transitions and the weak magnetism induced current in allowed nuclear $β$ decay

$r$ -process nucleosynthesis from compact binary mergers