abstract

Triggered by the experimentally-driven renewed interest in hyperon properties, we address the subject of weak radiative hyperon decays (WRHD). We start with the issue of Hara’s theorem and briefly discuss the question of its possible evasion. Then, we give a short review of the story of vector-meson-dominance (VMD) approach to WRHD. We stress the shift from the Hara’s-theorem-violating to Hara’s-theorem-satisfying version of the VMD approach that did occur over time. Finally, spurred by a recent theoretical paper, we discuss the pole model description of WRHD, putting special attention to the issue of the contributions from the intermediate \({\mit \Lambda }(1405)\) state. We point out that the measurement of the \({\mit \Lambda } \to n \gamma \) decay asymmetry could resolve the encountered ambiguities and definitely answer the question of whether Hara’s theorem is violated or not.

abstract

We have investigated the influence of isospin and shell effects on the proton decay half-lives of nuclei. In order to take into account these effects, new parameters related with isospin and shell effects have been added to the empirical formulas proposed in Phys. Rev. C 79, 054330 (2009) and Chin. Phys. C 42, 014104 (2018). The parameters of these new empirical formulas including isospin and shell effects have been fitted by 44 experimental available data comprising 29 ground states and 15 isomeric transitions of proton decay half-lives. The r.m.s. deviation between theory and experiment is decreased by inclusion of these modifications. The models have been applied to proton decaying nuclei whose experimental values are not yet known and then to actinide nuclei as well. Results consistent with the ones in the literature have been obtained. The role of the isospin and shell effects on the proton decay half-lives has been demonstrated.

abstract

The experimental energy ratio \(R_{4^+_1/2^+_1}\cong 2\) suggests \(^{116}\)Te as a prototypical vibrational nucleus. To test this hypothesis and also consider the possibility of deformation signatures in this nucleus, the energy spectra and energy surface are derived using the Interacting Boson Model including Configuration Mixing (IBMCM) and also an SU(1,1)-based transitional Hamiltonian in the both IBM 1 and 2 versions between U(5) and SO(6) dynamical limits. Both models reproduced the experimental energy levels by acceptable accuracy when the deformation effect is neglected. In addition, the results for control parameters of transitional Hamiltonians and the shape of energy surface propose an exactly U(5)-like structure for this nucleus.

abstract

We report on the triggering of localized and confined chaos described by a general cubic order damped nonlinear Schrödinger amplitude equation containing a conjugate amplitude term, representing the time-periodic parametric driving, and a spatially periodic term representing the external potential that cuts and confines the chaotic patterns promoted by the former, leading to trapped chaotic space-localized structures. Numerical simulations in \(1+1\), \(1+2\), and \(1+3\) dimensions, Lagrangian and Hamiltonian theories for continuous fields, moments method, largest Lyapunov exponents, spectral distributions, and bifurcations diagrams are used to characterize and analyze these chaotic solitons.

abstract

We report on the exact solution of a new modelled one-dimensional non-Hermitian quadratic operator generated using similarity transformation. In fact, the model Hamiltonian satisfies the \(T\)-symmetry condition i.e. \([H,T]=0\). Apart from analytical study, we perform necessary computational work to verify the analytical results.