Neutrino Mass Induced $n$-$\overline{n}$ Oscillation

Abstract

The Georgi-Glashow model is the simplest possible attempt at grand unification. However, due to its particle content, the model preserves a global $U(1)_{B-L}$ symmetry, where $B$ and $L$ are baryon and lepton numbers, respectively. It thus leaves neutrinos massless just as the Standard Model does. The extensions of the Georgi-Glashow model that break lepton number by two units, i.e., scenarios with $|ΔL|=2$ operator(s), naturally generate potentially viable Majorana neutrino masses. Since the dynamics that yields $|ΔL| = 2$ interactions unavoidably induces $|ΔB| = 2$ transitions via $B\!-\!L$ breaking, these extensions consequentially lead to intriguing processes such as neutron--antineutron ($n$--$\overline{n}$) oscillation. We investigate this intrinsic connection between neutrino mass generation and $n$--$\overline{n}$ oscillation within a number of representative extensions of the Georgi-Glashow model that can yield realistic neutrino masses and mixing parameters. These extensions include the tree-level seesaw mechanism realizations of the Type I, II, and III varieties, as well as the one-loop and two-loop radiative neutrino mass models.