α-decay half-lives ( T 1 / 2 α -values) of even–even and superheavy nuclei (SHN) are determined employing interaction potential involving Coulomb and proximity potentials. The obtained results are compared with the experimental ones and to assess the precision of the present model in reproducing the experimental half-lives, a comparison is drawn with the other methods as well. We require disintegration energy (Q α -values) as an input in order to predict the ( T 1 / 2 α -values) of an experimentally unknown SHN. So, utilizing periodic-orbit theory within microscopic-macroscopic formalism, we have calculated the binding energies and thereafter, Q α -values of known SHN. The results are found to be in good agreement with the experimental ones. Subsequently, we predict the logarithmic values of T 1 / 2 α ’s for even–even unknown SHN whose atomic numbers lie in 118 ⩽ Z ⩽ 126 regime and compare our results with those calculated employing other theoretical methods. Also, the study of spontaneous fission half-lives and branching ratios leads us to predict the SHN which can be identified through α-decay chains in the laboratories. We believe that this work can play a significant role in the experiments leading to the synthesis and identification of new superheavy elements.

The cross sections of the 121Sb(n,2n) 120Sbm and 123Sb(n,2n) 122Sb reactions were measured at 12.50, 15.79 and 18.87 MeV neutron energies relative to the standard 27Al(n,α) 24Na monitor reaction using neutron activation and offline γ-ray spectrometry technique. Irradiations of the samples were performed at the BARC-TIFR Pelletron Linac Facility, Mumbai, India. The quasi-monoenergetic neutron was generated via the 7Li(p,n) reaction. Statistical model calculations were performed by nuclear reaction codes TALYS (ver. 1.9) and EMPIRE (ver. 3.2.2) using various input parameters and nuclear level density models. The cross sections of the ground and the isomeric state as well as the isomeric cross section ratio were studied theoretically from reaction threshold to 26 MeV energies. The effect of pre-equilibrium emission is also discussed in detail using different theoretical models. The present measured cross section were discussed and compared with reported experimental data and evaluation data of the JEFF-3.3, ENDF/B-VIII.0, JENDL/AD-2017 and TENDL-2019 libraries. A detailed analysis of the uncertainties in the measured cross section data was performed using the covariance analysis method. Furthermore, a systematic study of the (n,2n) reaction cross section for 121Sb and 123Sb isotopes were also performed within 14-15 MeV neutron energies using various systematic formulae. This work helps to overcome discrepancies in Sb data and illustrate a better understanding of pre-equilibrium emission in (n,2n) reaction channel.

Cluster-decay half-lives (T c,th 1/2 (s)) of even-even nuclei are calculated employing interaction potential involving Coulomb and proximity potentials and, the obtained results are compared with the experimental ones. In order to study cluster radioactivity in even-even superheavy nuclei (SHN), we evaluate the required disintegration energies (Qc-values) utilizing periodic-orbit theory within microscopic-macroscopic formalism and hence, predict the logarithmic values of T c,th 1/2 ’s for even-even 298−312Og and 296−310120 nuclei. Among various isotopes of daughter nuclei, products produced with minimum value of Gibbs free energy are chosen for our investigation. Also, an analysis of the branching ratios enables us to determine the dominant mode of decay among α− decay, spontaneous fission (SF) and cluster-decay in these SHN. The emissions of 90Kr from 298Og and 94Sr cluster from 296,298120 SHN are found to be the dominant mode of decay. Our results are in agreement with those obtained using UDL method except for few cases. We believe that this work can play a significant role in the experiments leading to identification of exotic nuclei.

We calculate BSM hadronic matrix elements for K 0-K 0 mixing in the Dual QCD approach (DQCD). The ETM, SWME and RBC-UKQCD lattice collaborations find the matrix elements of the BSM density-density operators O i with i = 2-5 to be rather different from their vacuum insertion values (VIA) with B 2 ≈ 0.5, B 3 ≈ B 5 ≈ 0.7 and B 4 ≈ 0.9 at µ = 3 GeV to be compared with B i = 1 in the VIA. We demonstrate that this pattern can be reconstructed within the DQCD through the nonperturbative meson evolution from very low scales, where factorization of matrix elements is valid, to scales O(1 GeV) with subsequent perturbative quark-gluon evolution to µ = 3 GeV. This turns out to be possible in spite of a very different pattern displayed at low scales with B 2 = 1.2, B 3 = 3.0, B 4 = 1.0 and B 5 ≈ 0.2 in the large-N limit, N being the number of colours. Our results imply that the inclusion of meson evolution in the phenomenology of any non-leptonic transition like K 0-K 0 mixing and K → ππ decays is mandatory. While meson evolution, as demonstrated in our paper, is hidden in lattice QCD results, to our knowledge, DQCD is the only analytic approach for non-leptonic transitions and decays which takes this important strong dynamics into account.