Search for new physics in double beta decay of82Se with the CUPID-0 Background Model

CUPID-0 is a pilot experiment in scintillating cryogenic calorimetry for the search of neutrinoless double β decay. 26 ZnSe crystals coupled to bolometric light detectors were operated continuously for two years. From its successful experience comes a demonstration of full α to β/γ background separation, the most stringent limit on the82Se neutrinoless double β decay, as well as the most precise measurement of the82Se two-neutrino double β decay half-life. We developed a model to constrain the contribution of several sources in a wide energy region, demonstrating that CUPID-0 reached unprecedented low levels of background in the region of interest at the Q-value of82Se. CUPID-0 is sensitive to the spectral shape of the two-neutrino double β decay, and it already provided evidence for its single state dominance. In this contribution we search for spectral distortions due to exotic decay modes. Through a Bayesian approach we investigate the Lorentz violation in the two-neutrino double beta decay and several conjuctured models providing the neutrino-less double beta decay with the emission of a Majoron-like particle.