Effective Theory and Simple Completions for Neutrino Interactions

Abstract

We consider all the dimension 6 operators as well as some simple extensions of the standard model that give new contributions to neutrino interactions with matter. Such interactions are usually parametrized by ${ϵ}_{\alpha \beta }$, where $\alpha$ and $\beta$ are neutrino flavor indices taking the values $e$, $\mu$ and $\tau$. In the simple models we consider the ${ϵ}_{\alpha \beta }$'s are much more constrained than in the operator-based model-independent approach. Typically the ${ϵ}_{\alpha \beta }$'s are restricted to be smaller in magnitude than around $10^{-3}$. In some of the leptoquark models, a specific pattern for the leptoquark Yukawa couplings allows the diagonal element ${ϵ}_{\tau \tau }$ to be as large as $\sim 0.1$, or one of ${ϵ}_{ee}$, ${ϵ}_{\mu \mu }\sim 0.01$. We discuss the interplay between neutrino physics and leptoquark searches at the LHC.

Comments: 12 pages, 2 figures