Five-leg photon-neutrino interactions

Abstract

In a first part, we justify the feasibility of substituting a photon leg by a neutrino current in the Euler-Heisenberg Lagrangian to obtain an effective Lagrangian for the process $\gamma \nu \to \gamma \gamma \nu$ and its crossed reactions. We establish the link between these processes and the four-photon scattering in both the Standard Model and the effective theory. As an application, we compute in this effective theory the processes $\gamma \nu \to \gamma \gamma \nu$ and $\gamma \gamma \to \gamma \nu \bar{\nu }$ and show how to use the $\gamma \gamma \to \gamma \gamma$ results as a check. We settle the question of the disagreement between two computations in the literature concerning the reaction $\gamma \gamma \to \gamma \nu \bar{\nu }$. In the second part, we present results of the direct computation of the photon-neutrino five-leg processes in the Standard Model, discuss possible astrophysical implications of our results, and provide simple fits to the exact expressions.

6 pages, axodraw, ltwol2e, 5 figures, contributed paper to the 29th International Conference on High Energy Physics (Vancouver)