Chiral matching of dimension-7 baryon-number-violating operators and application to $\Delta I=3/2$ nucleon decays

Abstract

We study chiral matching of dimension-7 (dim-7) baryon-number-violating operators in low-energy effective field theory. We show that all dim-7 operators can be classified into two distinct Lorentz structures and their chirality-flipped counterparts, and we derive their leading-order hadronic realizations in chiral perturbation theory. As an application, we systematically investigate $\Delta I=3/2$ nucleon decays, including $n\to {\ell }^{-}{\pi }^{+}$, $p\to {\ell }^{-}{\pi }^{+}{\pi }^{+}$, and $n\to {\ell }^{-}{\pi }^{+}({\pi }^0,\eta )$, with $\ell =e,\mu$. Using existing experimental bounds on $n\to {\ell }^{-}{\pi }^{+}$, we set stringent constraints on the relevant Wilson coefficients and derive improved lower limits on the partial lifetimes of the six three-body modes from their correlations with the two-body modes. We further present a concrete ultraviolet model that generates the dim-7 operators and the associated $\Delta I=3/2$ nucleon decays at leading order. Our results pave the way for exploring dim-7 contributions to nucleon decays and motivate future searches for these exotic modes.

Comments: 12 pages, 6 figures