Observable Proton Decay from Planck Scale Physics

Abstract

In the Standard Model, no dim-5 $\Delta B\ne 0$ operators exist, so that Planck-scale-induced proton decay amplitudes are suppressed by at least $1/M_{P\ell }^2$. If the Standard Model is augmented by a light, color-non-singlet boson, then $O(1/M_{P\ell })$ proton-decay amplitudes are possible. These always conserve $B+L$, so that the dominant decay modes are $p\to {\Pi }^{+}\nu$ and $p\to {\Pi }^{+}{\Pi }^{+}{\ell }^{-}$, where ${\Pi }^{+}={\pi }^{+}$ or $K^{+}$.

Comments: 5 pages, 2 figures, 3 tables. Added one table and more discussion of experimental and theoretical limits