Distributions for tau neutrino interactions observed through the decay $\tau\rightarrow \mu\nu_\tau\bar\nu_\mu$

TL;DR

This paper develops analytical methods to distinguish tau neutrino interactions from muon neutrino interactions in large neutrino telescopes by analyzing event distributions, aiding in the detection of high-energy tau neutrinos.

Contribution

It introduces new analytical and numerical techniques to identify tau neutrino events based on energy distribution variables, enhancing detection capabilities in neutrino telescopes.

Findings

The $y'$-distribution has a characteristic minimum at 0.75 for $ u_\tau$ interactions.

The $y'$-distribution behaves differently for $ u_\mu$ interactions, decreasing monotonically.

Ratios of distributions can factor out the neutrino flux, simplifying analysis.

Abstract

We investigate the problem of identifying $\nu_\tau$-induced reactions in large neutrino telescopes. We concentrate on events with tracks and showers where the respective energies $E_\mu$ and $E_X$ are measured separately. Then we compute analytically and numerically event distributions in two variables $r_l = E_X/E_l$ and $y'=E_{\text{X}}/(E_{\mu}+E_{X})$. We find that the $y'$-distribution is especially useful because in the $\nu_\tau$-induced reactions the distribution has a minimum at $y'=0.75$ and then increases as $y'\rightarrow1$. This is different in $\nu_\mu$-induced reactions where the $y'$-distribution decreases monotonically. The results are demonstrated with figures where one can estimate the required sensitivity of the experiments. Another attractive property is that in several ratios the neutrino flux factorizes and drops out. We hope the results of this article will be useful for searches of tau (anti)neutrinos of energies above 100 GeV to several TeV in the present and planned large volume neutrino telescopes.