$SU_{L}(4)\times U(1)$ model for electroweak unification and sterile   neutrinos
  Some of basic problems in neutrino physics such as new energy scales, the enormous gap between neutrino masses and the lightest charged fermion mass, possible existance of sterile neutrinos in eV mass range are studied in the local gauge group $SU_{L}(4)\times U(1)$ for electroweak unification, which does not contain fermions with exotic electric charges. It is shown that neutrino mass spectrum can be decoupled from that of the other fermions. Further normal seesaw mechanism for neutrinos, with right handed neutrino Majorana masses to be of order $M\gg M_{\text{weak}}$ as well a new eV-scale can be accomodated. The eV-scale seesaw may manifest itself in experiments like Liquid Scintilation Neutrino Detector (LSND) and MiniBooNE (MB) experimental results and future neutrino experiments. 
Riazuddin and Fayyazuddin