A statistical analysis of the COHERENT data and applications to new physics

The observation of coherent elastic neutrino nucleus scattering (CE nu NS) by the COHERENT collaboration in 2017 has opened a new window to both test Standard Model predictions at relatively low energies and probe new physics scenarios. Our investigations show, however, that a careful treatment of the statistical methods used to analyze the data is essential to derive correct constraints and bounds on new physics parameters. In this manuscript we perform a detailed analysis of the publicly available COHERENT CsI data making use of all available background data. We point out that Wilks' theorem is not fulfilled in general and a calculation of the confidence regions via Monte Carlo simulations following a Feldman-Cousins procedure is necessary. As an example for the necessity of this approach to test new physics scenarios we quantify the allowed ranges for several scenarios with neutrino non-standard interactions. Furthermore, we provide accompanying code to enable an easy implementation of other new physics scenarios as well as data files of our results: https://github.com/JuliaGehrlein/7stats.

Automated summary

The observation of coherent elastic neutrino nucleus scattering in 2017 has allowed for testing Standard Model predictions at low energies and exploring new physics scenarios. It is essential to carefully handle statistical methods when analyzing data in order to derive correct constraints on new physics parameters. A detailed analysis of COHERENT CsI data revealed the necessity of using Monte Carlo simulations to calculate confidence regions for testing new physics scenarios.