New physics searches at near detectors of neutrino oscillation experiments

TL;DR

This paper evaluates the potential of near detectors at neutrino experiments to detect new physics effects, especially tau neutrino appearance, by analyzing effective operators and current experimental bounds.

Contribution

It provides a comprehensive analysis of new physics operators affecting tau neutrino appearance and assesses the sensitivity of near detectors at various neutrino sources.

Findings

Tau neutrino appearance probabilities can reach 10^{-4}.

Near detectors can probe new physics effects within current experimental bounds.

First complete analysis of operators with two leptons and two quarks using MCMC.

Abstract

We systematically investigate the prospects of testing new physics with tau sensitive near detectors at neutrino oscillation facilities. For neutrino beams from pion decay, from the decay of radiative ions, as well as from the decays of muons in a storage ring at a neutrino factory, we discuss which effective operators can lead to new physics effects. Furthermore, we discuss the present bounds on such operators set by other experimental data currently available. For operators with two leptons and two quarks we present the first complete analysis including all relevant operators simultaneously and performing a Markov Chain Monte Carlo fit to the data. We find that these effects can induce tau neutrino appearance probabilities as large as O(10^{-4}), which are within reach of forthcoming experiments. We highlight to which kind of new physics a tau sensitive near detector would be most sensitive.