Nuclear Theory·nucl-th

Friday·March 29, 2024

10 papers—6 primary·4 cross-listed

01
Inner fission barriers of uranium isotopes in the deformed relativistic Hartree-Bogoliubov theory in continuum
Wei Zhang · Jin-Ke Huang · Ting-Ting Sun · Jing Peng · Shuang Quan Zhang
The inner fission barriers of the even-even uranium isotopes from the proton to the neutron drip line are studied with the deformed relativistic Hartree-Bogoliubov theory in continuum. A periodic evolution for the ground state shapes is shown with the neutron number, i.e., spherical shapes at shell closures $N =$ 126, 184, 258, and prolate dominated shapes between them. In analogy to the shape evolution, the inner fission barriers also exhibit a periodic behavior: peaks at the shell closures and valleys in the mid-shells. The triaxial effect to the inner fission barrier is evaluated using the triaxial relativistic mean field calculations plus a simple BCS method for pairing. With the triaxial correction included, good consistency in the inner barrier heights is found with the available empirical data. Besides, the evolution from the proton to the neutron drip line is in accord with the results by the multi-dimensionally constrained relativistic mean field theory. A flat valley in the fission barrier height is predicted around the neutron-rich nucleus $^{318}$ U which may play a role of fission recycling in the astrophysical $r$ -process nucleosynthesis.
nucl-thCPC(2024)·8 citations
02
Algorithm to Obtain Inverse Potentials for $α - α$ Scattering using Variable Phase Approach
Anil Khachi · Shikha Awasthi · Lalit Kumar · O.S.K.S Sastri
An algorithm $^{\ref F i g 1}$ has been developed with the purpose of obtaining inverse potentials, where the Riccati-type non-linear differential equation, also called phase equation, has been kept in tandem with the Variational Monte Carlo method. The optimization of Gaussian function parameters is achieved such that the experimental phase shifts are reproduced. The obtained SPS for various $e l l$ channels has been compared with experimental ones with mean absolute percentage error (MAPE) as a measure. The model parameters have been optimised by suitable optimisation technique by looking for minimum value of MAPE. The results for $ℓ$ =0 $^{+}$ , 2 $^{+}$ and 4 $^{+}$ partial waves have been obtained, to match with experimental SPS, with MAPE values of $2.9$ , $4.6$ and $6.2$ respectively for data up to $23$ MeV, while for higher states 6 $^{+}$ , 8 $^{+}$ and 10 $^{+}$ has MAPE of $3.2, 4.5$ and $5.9$ respectively for data from $53 - 120$ MeV. On extrapolation for data in range E $_{ℓ ab .}$ = $23 - 120$ MeV, using the optimised parameters, the SPS are found to be in close agreement with experimental ones for the first three channels.
nucl-thComput.Math.Math.Phys.(2024)·3 citations
03
Cross-checking the geometric effects in heavy-ion collisions at 1 GeV/nucleon
Zu-Xing Yang · Xiao-Hua Fan · Zhi-Pan Li · Shunji Nishimura
Employing the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, the 1 GeV/nucleon deformed uranium-uranium ultra-central collisions are simulated. Based on sensitive observables, mean square collective flow and pion meson multiplicity, the impacts of high-momentum tails caused by short-range correlations and the symmetry energy in high-density regions on geometric effects are discussed under different reaction orientations. Finally, the neural network model for identifying reaction orientations is also developed.
nucl-thnucl-ex0 citations
04
Entanglement in multinucleon transfer reactions
B. Li · D. Vretenar · T. Nikšić · D. D. Zhang · P. W. Zhao · J. Meng
Nuclear reactions present an interesting case for studies of the time-evolution of entanglement between complex quantum systems. In this work, the time-dependent nuclear density functional theory is employed to explore entanglement in multinucleon transfer reactions. As an illustrative example, for the reaction $^{40}$ Ca $+$ $^{208}$ Pb at $E_{lab} = 249$ MeV, in the interval of impact parameters $4.65 - 7.40$ fm, and the relativistic density functional PC-PK1, we compute the von Neumann entropies, entanglement between fragments, nucleon-number fluctuations, and Shannon entropy for the nucleon-number observable. A simple linear correlation is established between the entanglement and nucleon-number fluctuation of the final fragments. The entanglement between the fragments can be related to the corresponding excitation energies and angular momenta. The relationship between the von Neumann entropy and the Shannon entropy for the nucleon-number observable is analyzed, as well as the time-evolution of the entanglement (nucleon-number fluctuation). The entanglement is also calculated for a range of incident energies and it is shown how, depending on the impact parameter, the entanglement increases with the collision energy.
nucl-thPRC(2024)·19 citations
05
Bayesian inference of the dense matter equation of state built upon extended Skyrme interactions
Mikhail V. Beznogov · Adriana R. Raduta
The non-relativistic model of nuclear matter with Brussels extended Skyrme interactions is employed in order to build, within a Bayesian approach, models for the dense matter equation of state (EOS). In addition to a minimal set of constraints on nuclear empirical parameters; the density behavior of the energy per particle in pure neutron matter (PNM); a lower limit on the maximum neutron star (NS) mass, we require that the Fermi velocity of neutrons ( $v_{F; n}$ ) in PNM and symmetric nuclear matter (SNM) with densities up to $0.8 fm^{- 3}$ (arbitrary) does not exceed the speed of light. The latter condition is imposed in order to cure a deficiency present in many Skyrme interactions [Duan and Urban, Phys. Rev. C 108, 025813 (2023)]. We illustrate the importance of this constraint for the posterior distributions. Some of our models are subjected to constraints on the density dependence of neutron (nucleon) Landau effective mass in PNM (SNM), too. The impact of various sets of constraints on the behaviors of nuclear matter and NSs is discussed in detail. Systematic comparison with results previously obtained by employing Skyrme interactions is done for posteriors of both nuclear matter (NM) and NS parameters. Special attention is given to the model and constraints dependence of correlations among various quantities.
nucl-thPRC(2024)·18 citations
06
Extended Nambu--Jona-Lasinio model for quark and nuclear matters
Gaoqing Cao🇨🇳
In this work, we extend the two-flavor Nambu--Jona-Lasinio model to one capable of exploring quark and nuclear matter consistently. With an extra term standing for quark-nucleon interactions, nucleons could automatically emerge as color-singlet three-quark entities by following a process similar to mesons. Besides the quark part in mean field approximation, both mesons and nucleons could contribute to the thermodynamic potential thus possibly give rise to quarkyonic matter beyond mean field. In the study, two kinds of "confining" couplings are adopted for the new interaction term and two different quark masses are considered for comparison. It turns out that only confined nuclear matter or deconfined quark matter is possible for all the cases at zero temperature, thus quarkyonic matter is not favored at all. Even more strictly, only the case with stronger confinement effect and a smaller quark mass admits a physical first-order phase transition from nuclear matter to quark matter around twice saturation density.
nucl-thcond-mat.supr-conhep-phPLB(2025)·2 citations
07
Prospects for PIONEER
Martin Hoferichter
Pion $β$ decay, $π^{+} \to π^{0} e^{+} ν_{e}$ , offers a pristine way to measure the CKM matrix element $V_{u d}$ in a purely mesonic system, with excellent control over the hadronic matrix elements. We review the physics goals and current status of the PIONEER experiment, which aims at major improvements in the branching fractions for the $π^{+} \to e^{+} ν_{e}$ decay in Phase I and for pion $β$ decay in Phases II and III of its experimental program, potentially leading to a measurement of $V_{u d}$ competitive with determinations from $β$ decays involving nucleons.
↳ hep-phhep-exnucl-th2 citations
08
Exact evaluation of large-charge correlation functions in non-relativistic conformal field theory
Silas R. Beane🇨🇭 · Domenico Orlando🇨🇭 · Susanne Reffert🇨🇭
The large-charge master field which generates all n-point correlation functions with an insertion of large charge Q in non-relativistic conformal field theory is obtained. This field is used to compute Schrödinger-invariant n-point correlation functions of large-charge operators via a direct evaluation of the path integral. Conformal dimensions are found to agree with calculations based on the state-operator correspondence. The master field solution exhibits an emergent harmonic trap whose frequency is a function of the Euclidean time. The large-charge effective action with operator insertions describes a droplet of superfluid matter whose spatial size scales with the time separation of sources. The solution is used to compute Schrödinger symmetry breaking corrections in the large-charge effective field theory (EFT) due to a finite scattering length in the fundamental theory of fermions near unitarity. The scaling of these effects in the large-charge power counting scheme is established, and the size of the effects is quantified using input from quantum Monte Carlo simulations of the near-unitary gas, as well as from the large-N expansion at large charge.
↳ hep-thcond-mat.quant-gashep-phnucl-thPRD(2024)·5 citations
09
Reference Energies for Double Excitations: Improvement and Extension
Fábris Kossoski · Martial Boggio-Pasqua · Pierre-François Loos · Denis Jacquemin
In the realm of photochemistry, the significance of double excitations (also known as doubly-excited states), where two electrons are concurrently elevated to higher energy levels, lies in their involvement in key electronic transitions essential in light-induced chemical reactions as well as their challenging nature from the computational theoretical chemistry point of view. Based on state-of-the-art electronic structure methods (such as high-order coupled-cluster, selected configuration interaction, and multiconfigurational methods), we improve and expand our prior set of accurate reference excitation energies for electronic states exhibiting a substantial amount of double excitations [http://dx.doi.org/10.1021/acs.jctc.8b01205; Loos et al. J. Chem. Theory Comput. 2019, 15, 1939]. This extended collection encompasses 47 electronic transitions across 26 molecular systems that we separate into two distinct subsets: (i) 28 "genuine" doubly-excited states where the transitions almost exclusively involve doubly-excited configurations and (ii) 19 "partial" doubly-excited states which exhibit a more balanced character between singly- and doubly-excited configurations. For each subset, we assess the performance of high-order coupled-cluster (CC3, CCSDT, CC4, and CCSDTQ) and multiconfigurational methods (CASPT2, CASPT3, PC-NEVPT2, and SC-NEVPT2). Using as a probe the percentage of single excitations involved in a given transition ( $% T_{1}$ ) computed at the CC3 level, we also propose a simple correction that reduces the errors of CC3 by a factor of 3, for both sets of excitations. We hope that this more complete and diverse compilation of double excitations will help future developments of electronic excited-state methodologies.
↳ physics.chem-phcond-mat.mtrl-scicond-mat.str-elnucl-thJ.Chem.Theor.Comput.(2024)·1 citation
10
Angular dependence in transverse momentum dependent diffractive parton distributions at small- $x$
Yoshitaka Hatta🇺🇸 · Feng Yuan🇺🇸
We discuss the angular dependence of the recently proposed transverse momentum dependent quark and gluon diffractive parton distributions at small- $x$ . We introduce the difractive versions of the Sivers function and the elliptic gluon Wigner distribution and evaluate them in simple models with gluon saturation and study their geometric scaling properties. We also show that the diffractive version of the linearly polarized gluon distribution identically vanishes to leading order. These distributions enrich the physics opportunities for measuring semi-inclsuive diffractive DIS processes at the future electron-ion colliders.
↳ hep-phhep-exnucl-exnucl-thPLB(2024)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE