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Effective Theory and Simple Completions for Neutrino Interactions

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 $ε_{αβ}$, where $α$ and $β$ are neutrino flavor indices taking the values $e$, $μ$ and $τ$. In the simple models we consider the $ε_{αβ}$'s are much more constrained than in the operator-based model-independent approach. Typically the $ε_{αβ}$'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 $ε_{ττ}$ to be as large as $\sim0.1$, or one of $ε_{ee}$, $ε_{μμ}\sim0.01$. We discuss the interplay between neutrino physics and leptoquark searches at the LHC.