Results from the OPERA experiment

TL;DR

The OPERA experiment confirmed $ u_{ au}$ appearance due to oscillations with high significance and analyzed the data within a 3+1 neutrino model, setting limits on oscillation parameters.

Contribution

This paper reports the first observation of $ u_{ au}$ appearance in a long baseline experiment and provides constraints on 3+1 neutrino oscillation models.

Findings

Detection of 5 $ u_{ au}$ candidates with >5σ significance.

Set limits on 3+1 neutrino oscillation parameters.

Demonstrated capability to identify $ u_{e}$ CC events.

Abstract

The OPERA long baseline experiment located in the INFN Gran Sasso underground Laboratory was designed to establish the $\nu_{\mu}$ $\rightarrow$ $\nu_{\tau}$ oscillations in appearance mode, using the CNGS neutrino beam. Five $\nu_{\tau}$ candidate events have been detected in a data sample from the 2008-2012 runs, with a expected background of 0.25 events. The background only hypothesis is rejected with a significance larger than 5${\sigma}$. The analysis of the tau neutrino sample in the framework of the 3+1 neutrino model is presented. OPERA is able to identify $\nu_{e}$ CC events due to the good tracking capabilities of its target. The electron neutrino sample is also used to set limits on the 3+1 oscillation parameters.