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Complete fusion excitation function for the 6 Li + 144 Sm reaction has been measured at near barrier energies by the activation technique. Coupled-channel calculations show an enhancement in fusion cross section at energies below the barrier compared to the one-dimensional barrier penetration model calculation, but they overpredict it in the entire energy range compared to the experimental data. Reduced fusion cross sections for the present system at energies normalized to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus. These two observations conclusively show that the complete fusion cross section, at above barrier energies, is suppressed by ∼32% in the 6 Li + 144 Sm reaction. Reanalyses of existing fusion data for 7 Li + 165 Ho and 7 Li + 159 Tb also show a suppression compared to those with strongly bound projectiles, which contradicts earlier conclusions. The fusion suppression factor seems to exhibit a systematic behavior with respect to the breakup threshold of the projectile and the atomic number of the target nucleus.

The two neutrino double beta decay of 94,96 Zr, 98,100 Mo, 104 Ru and 110 Pd nuclei for 0 + → 0 + transition is studied in the PHFB model in conjunction with the summation method. In the first step, the reliability of the intrinsic wave functions has been established by obtaining an overall agreement between a number of theoretically calculated spectroscopic properties and the available experimental data for 94,96 Zr, 94,96,98,100 Mo, 98,100,104 Ru, 104,110 Pd and 110 Cd isotopes. Subsequently, the PHFB wave functions of the above mentioned nuclei are employed to calculate the nuclear transition matrix elements M 2ν as well as half-lives T 2ν 1/2 . Further, we have studied the effects of deformation on the M 2ν .

The (β − β − ) 0ν decay of 94,96 Zr, 98,100 Mo, 104 Ru, 110 Pd, 128,130 Te, and 150 Nd isotopes for the 0 + → 0 + transition is studied in the projected Hartree-Fock-Bogoliubov framework. In our earlier work, the reliability of HFB intrinsic wave functions participating in the β − β − decay of the above-mentioned nuclei has been established by obtaining an overall agreement between the theoretically calculated spectroscopic properties, namely yrast spectra, reduced B(E2 : 0 + → 2 + ) transition probabilities, quadrupole moments Q(2 + ), gyromagnetic factors g(2 + ) as well as half-lives T 2ν 1/2 for the 0 + → 0 + transition and the available experimental data. In the present work, we study the (β − β − ) 0ν decay for the 0 + → 0 + transition in a mechanism involving neutrino mass and extract limits on effective mass of light as well as heavy neutrinos from the observed half-lives T 0ν 1/2 (0 + → 0 + ) using nuclear transition matrix elements calculated with the same set of wave functions. Further, the effect of deformation on the nuclear transition matrix elements required to study the (β − β − ) 0ν decay in such a mass mechanism is investigated. It is noticed that the deformation effect on nuclear transition matrix elements is of approximately the same magnitude in (β − β − ) 2ν and (β − β − ) 0ν decay.