This is Neutron decay: $$n^o \to p^+ + e^- + \overline {\nu_e}.$$ and this is proton one: $$p^+ \to n^o + e^+ + \nu_e$$
so when the $e^+ =e^-$ and $\nu_e=\overline {\nu_e}$ why $n \not= p$?
my idea is that:
$$\nu_e \not= \overline {\nu_e}$$ is my theory correct?