A careful analysis of$$B_d^0 - \bar B_d^0 $$ mixing data, incorporating the most recent QCD corrections to the parameterx_d, as well as the recent data regarding the matrix elements |V_ub| and |V_cb| leads to a reliable lower limit on mass oft-quark, for examplem_t ⩾ 115 GeV.

Fritzsch like mass matrices with non-zero 22-elements both in U sector and D sector have been investigated in the context of latest data regardingm_t^phys, |V_ub|, |V_cb|, |V_td| and |V_ts|. Unlike several other phenomenological models, the present model not only accommodates the value ofm_t^phys in the range 150–240 GeV, encompassing the CDF and D0 values, but is also able to reproduce |V_cb| ≊0.040 and |V_ub/V_cb| = 0.08±0.02 and |V_td| is predicted to lie in the range 0.005–0.014. Further, the angles of the unitarity triangle, related to the CP-violating asymmetries, are calculated to be in the ranges −1.0⩽sin2α⩽−0.1, 0.6 ⩽sin2α⩽1.0 and 0.48⩽sin2β⩽0.56, which are in agreement with other recent calculations.

We study the implications of a large value of the effective Majorana neutrino mass for a class of two-texture zero neutrino mass matrices in the flavour basis. We find that these textures predict near-maximal atmospheric neutrino mixing angle in the limit of large effective Majorana neutrino mass. We present the symmetry realization of these textures using the discrete cyclic group Z₃. It is found that the texture zeros realized in this work remain stable under the renormalization group running of the effective neutrino mass matrix at one-loop level.

Despite spectacular advances in fixing the neutrino mass and mixing parameters through various neutrino oscillation experiments, we still have little knowledge about the magnitudes of some vital parameters in the neutrino sector such as the absolute neutrino mass scale, effective Majorana mass m_ee measured in neutrinoless double beta decay. In this context, the present work aims to make an attempt to obtain some bounds for m_ee and the lightest neutrino mass using fairly general lepton mass matrices in the Standard Model.