Nuclear Theory·nucl-th

Tuesday·January 23, 2024

15 papers—6 primary·9 cross-listed

01
Quark propagator with complex-valued momentum from Schwinger-Dyson equation in the Euclidean space
Shaoyang Jia🇺🇸 · Ian Cloët🇺🇸
In the Euclidean-space formulation of integral equations for the structure of quantum chromodynamics (QCD) bound states, the quark propagators with complex-valued momentum are densely sampled. We therefore propose an accurate and efficient algorithm to compute these propagators. The quark propagator both on the spacelike real axis and at complex-valued momenta is determined from its Schwinger-Dyson equation (SDE). We first apply an iterative solver to determine the quark propagator on the spacelike real axis. The propagator at complex-valued momenta is then computed from its self-energy based on this solution, where demanding integrals are encountered. In order to compute of these integrals, we apply customized variable transformations for the radial integral after subtracting the asymptotics. We subsequently apply an optional compound of quadrature rules for the angular integral. The contribution from the asymptotics is added at the last step. The accuracy and the performance of this algorithm for the quark propagator at complex-valued momentum are tested in comparison with an adaptive quadrature.
nucl-thhep-th2 citations
02
Abnormal Bifurcation of the Double Binding Energy Differences and Proton-Neutron Pairing: Nuclei Close to $N = Z$ Line from Ni to Rb
Y. P. Wang · Y. K. Wang · F. F. Xu · P. W. Zhao · J. Meng
The recently observed abnormal bifurcation of the double binding energy differences $δ V_{p n}$ between the odd-odd and even-even nuclei along the $N = Z$ line from Ni to Rb has challenged the nuclear theories. To solve this problem, a shell-model-like approach based on the relativistic density functional theory is established, by treating simultaneously the neutron-neutron, proton-neutron, and proton-proton pairing correlations both microscopically and self-consistently. Without any \textit{ad hoc} parameters, the calculated results well reproduce the observations, and the mechanism for this abnormal bifurcation is found to be due to the enhanced proton-neutron pairing correlations in the odd-odd $N = Z$ nuclei, compared with the even-even ones. The present results provide an excellent interpretation for the abnormal $δ V_{p n}$ bifurcation, and provide a clear signal for the existence of the proton-neutron pairing correlations for nuclei close to the $N = Z$ line.
nucl-thPRL(2024)·16 citations
03
Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes
S.V. Sidorov · A.S. Kornilova · T.Yu. Tretyakova
The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work. Tensor forces are taken into account within the framework of the Hartree-Fock approach with the Skyrme interaction. It is shown that the addition of tensor component of interaction improves the description of the splitting between different single-particle states and leads to a decrease in nucleon-nucleon pairing correlations in silicon and nickel nuclei. Special attention was given to the role of isovector tensor forces relevant for interaction of like nucleons.
nucl-thnucl-exCPC(2024)·0 citations
04
Weakening of $N = 28$ shell gap and the nature of $0_{2}^{+}$ states
Bhoomika Maheshwari · Kosuke Nomura
The work reports a novel application of the interacting boson model in light-mass region around $^{48}$ Ca, that takes into account intruder states and configuration mixing. The model is shown to provide a reasonable description of the observed low-lying yrast and yrare states of the $N = 28$ even-even isotones from Si to Fe, and even-even Ca isotopes. The nature of $0_{2}^{+}$ states is addressed in terms of the competition between spherical and deformed intruder configurations, and the rigidity of the $N = 28$ shell gap is tested. The $0_{2}^{+}$ isomer in $^{44}$ S is shown to arise from a weak mixing between the two configurations. The unresolved low-lying spectra in $^{46}$ Ar is also approached using the core-excitations across $N = 28$ shell. The SU(3) structure in $^{42}$ Si is supported by the present calculation. The nearly spherical nature of $^{50}$ Ti, $^{52}$ Cr, $^{54}$ Fe and $^{42, 44, 46}$ Ca isotopes is found, while the core excitations are found to be essential for the description of yrare states. Shell model calculation is also performed for comparison.
nucl-thnucl-exJ.Phys.G(2024)·4 citations
05
The N(1440) Roper resonance in the nuclear model with explicit mesons
D.V.Fedorov🇩🇰
We show that the N(1440) Roper resonance naturally appears in the nuclear model with explicit mesons as a structure in the continuum spectrum of the physical proton which in this calculation is made of a bare nucleon dressed with a pion cloud.
nucl-thhep-phFew Body Syst.(2024)·2 citations
06
Bayesian analysis of nontrivial features in the speed of sound inside neutron stars in light of astrophysical and pQCD constraints
Debora Mroczek🇺🇸
Functional forms of the neutron star Equation of State (EoS) are required to extract the viable EoS band from neutron star observations. Realistic nuclear EoS, containing deconfined quarks or hyperons, present nontrivial features in the speed of sound such as bumps, kinks, and plateaus. Using modified Gaussian processes to model EoS with nontrivial features, we show in a fully Bayesian analysis incorporating measurements from X-ray sources, gravitational wave observations, and perturbative QCD results that these features are compatible with current constraints. We find nontrivial behavior in the EoS plays a role in understanding the possible phase structure of neutron stars at densities around 2 $n_{sat}$ .
nucl-thhep-phEPJ Web Conf.(2024)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Quark propagator with complex-valued momentum from Schwinger-Dyson equation in the Euclidean space

Abnormal Bifurcation of the Double Binding Energy Differences and Proton-Neutron Pairing: Nuclei Close to N=Z Line from Ni to Rb

Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes

Weakening of N=28 shell gap and the nature of 02+​ states

The N(1440) Roper resonance in the nuclear model with explicit mesons

Bayesian analysis of nontrivial features in the speed of sound inside neutron stars in light of astrophysical and pQCD constraints

Affiliations

Abnormal Bifurcation of the Double Binding Energy Differences and Proton-Neutron Pairing: Nuclei Close to $N = Z$ Line from Ni to Rb

Weakening of $N = 28$ shell gap and the nature of $0_{2}^{+}$ states