Nuclear Theory·nucl-th

Friday·August 2, 2019

11 papers—7 primary·4 cross-listed

08
Measurement of the nuclear symmetry energy parameters from gravitational wave events
Carolyn A. Raithel🇺🇸 · Feryal Ozel🇺🇸
The nuclear symmetry energy plays a role in determining both the nuclear properties of terrestrial matter as well as the astrophysical properties of neutron stars. The first measurement of the neutron star tidal deformability, from gravitational wave event GW170817, provides a new way of probing the symmetry energy. In this work, we report on new constraints on the symmetry energy from GW170817. We focus in particular on the low-order coefficients: namely, the value of the symmetry energy at the nuclear saturation density, S_0, and the slope of the symmetry energy, L_0. We find that the gravitational wave data are relatively insensitive to S_0, but that they depend strongly on L_0 and point to lower values of L_0 than have previously been reported, with a peak likelihood near L_0 ~ 20 MeV. Finally, we use the inferred posteriors on L_0 to derive new analytic constraints on higher-order nuclear terms.
↳ astro-ph.HEnucl-th39 citations
09
The virial expansion of attractively interacting Fermi gases in 1D, 2D, and 3D, up to fifth order
Y. Hou · J. E. Drut
The virial expansion characterizes the high-temperature approach to the quantum-classical crossover in any quantum many-body system. Here, we calculate the virial coefficients up to the fifth-order of Fermi gases in 1D, 2D, and 3D, with attractive contact interactions, as relevant for a variety of applications in atomic and nuclear physics. To that end, we discretize the imaginary-time direction and calculate the relevant canonical partition functions. In coarse discretizations, we obtain analytic results featuring relationships between the interaction-induced changes $Δ b_{3}$ , $Δ b_{4}$ , and $Δ b_{5}$ as functions of $Δ b_{2}$ , the latter being exactly known in many cases by virtue of the Beth-Uhlenbeck formula. Using automated-algebra methods, we push our calculations to progressively finer discretizations and extrapolate to the continuous-time limit. We find excellent agreement for $Δ b_{3}$ with previous calculations in all dimensions and we formulate predictions for $Δ b_{4}$ and $Δ b_{5}$ in 1D and 2D. We also provide, for a range of couplings,the subspace contributions $Δ b_{31}$ , $Δ b_{22}$ , $Δ b_{41}$ , and $Δ b_{32}$ , which determine the equation of state and static response of polarized systems at high temperature. As a performance check, we compare the density equation of state and Tan contact with quantum Monte Carlo calculations, diagrammatic approaches, and experimental data where available. Finally, we apply Padé and Padé-Borel resummation methods to extend the usefulness of the virial coefficients to approach and in some cases go beyond the unit-fugacity point.
↳ cond-mat.quant-gasnucl-thPRA(2020)·11 citations
10
A computational EXFOR database
Georg Schnabel
The EXFOR library is a useful resource for many people in the field of nuclear physics. In particular, the experimental data in the EXFOR library serves as a starting point for nuclear data evaluations. There is an ongoing discussion about how to make evaluations more transparent and reproducible. One important ingredient may be convenient programmatic access to the data in the EXFOR library from high-level languages. To this end, the complete EXFOR library can be converted to a MongoDB database. This database can be conveniently searched and accessed from a wide variety of programming languages, such as C++, Python, Java, Matlab, and R. This contribution provides some details about the successful conversion of the EXFOR library to a MongoDB database and shows simple usage examples to underline its merits. All codes required for the conversion have been made available online and are open-source. In addition, a Dockerfile has been created to facilitate the installation process.
↳ cs.DLnucl-exnucl-thphysics.comp-ph+1EPJ Web Conf.(2020)·2 citations
11
Canonical interpretation of the newly observed $Λ_{b} (6146)^{0}$ and $Λ_{b} (6152)^{0}$ via strong decay behaviors
Wei Liang🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳
Stimulated by the newly observed $Λ_{b} (6146)^{0}$ and $Λ_{b} (6152)^{0}$ resonances, we investigate the strong decays of the low-lying singly bottom baryons within the quark pair creation model. Considering their masses and decay modes, we tentatively assign these states as the $λ -$ mode $Λ_{b} (2 S)$ , $Λ_{b} (1 D)$ , $Σ_{b} (2 S)$ , and $Σ_{b} (1 P)$ states, and then estimate their strong decay widths. Compared with the experimental total widths and decay modes measured by the LHCb Collaboration, the $Λ_{b} (6146)^{0}$ and $Λ_{b} (6152)^{0}$ can be reasonably clarified into the $J^{P} = 5/ 2^{+}$ and $J^{P} = 3/ 2^{+}$ $Λ_{b} (1 D)$ sates respectively, while other canonical assignments are disfavored. Other low-lying bottom states are also presented, where various narrow states may have good potential to be observed in future LHCb experiments.
↳ hep-phhep-exnucl-thPRD(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Measurement of the nuclear symmetry energy parameters from gravitational wave events

The virial expansion of attractively interacting Fermi gases in 1D, 2D, and 3D, up to fifth order

A computational EXFOR database

Canonical interpretation of the newly observed Λb​(6146)0 and Λb​(6152)0 via strong decay behaviors

Affiliations

Canonical interpretation of the newly observed $Λ_{b} (6146)^{0}$ and $Λ_{b} (6152)^{0}$ via strong decay behaviors