The number of neutrinos and the left-right symmetric model

The meaning of N-v in the Left-Right Symmetric Model (LRSM) is discussed. In its original definition N-v, is the number of neutrinos or generations of leptons, so, in the Standard Model its value is three. However the determination of N-v in experiments and in astrophysical observations is subject to different theoretical interpretations. We present arguments that gives N-v as a parameter of the LRSM. Using an experimental value for the rate Gamma(inv)/Gamma(l tau) we calculate the bound 2.90 less than or equal to N-vLR less than or equal to 3.04 (90% C. L.), where N-vLR is a function of the left-right mixing angle phi. This range is less restrictive than the one of the standard model.