Four-neutrino MS2 mixing

We present a simple scheme of mixing of four neutrinos that can accommodate the results of all neutrino oscillation experiments, the observed abundances of primordial elements produced in Big-Bang Nucleosynthesis and the current upper bound for the effective Majorana neutrino mass in neutrinoless double-β decay (assuming that massive neutrinos are Majorana particles). The scheme has maximal mixing in the νμ,ντ–ν3,ν4 sector and small mixings in the νe,νs–ν1,ν2 and νe,νμ–ν1,ν3 (or νe,νμ–ν1,ν4) sectors (MS2). We discuss the implications of this scheme for short and long baseline oscillation experiments and for neutrinoless double-β decay and tritium β-decay experiments.