eV seesaw with four generations

We extend the eV seesaw scenario to four lepton generations. The LSND anomaly is taken as the right-handed seesaw scale, i.e., mR∼eV. The fourth generation then gives a heavy pseudo-Dirac neutrino which largely decouples from other generations, and is relatively stable. One effectively has a 3+3 solution to the LSND anomaly, where we illustrate with numerical solutions. Our study seems to indicate that the third mixing angle sin2θ13 may be less than 0.01.