2025

Ressa, A.; Azzolini, O.; Beeman J., W.; Bellini, F.; Beretta, M.; Biassoni, M.; Brofferio, C.; Bucci, C.; Capelli, S.; Caracciolo, V.; Cardani, L.; Carniti, P.; Casali, N.; Celi, E.; Chiesa, D.; Clemenza, M.; Colantoni, I.; Cremonesi, O.; Cruciani, A.; D'Addabbo, A.; Dafinei, I.; Domizio S. Di; Dompè, V.; Fantini, G.; Ferroni, F.; Gironi, L.; Giuliani, A.; Gorla, P.; Gotti, C.; Keppel, G.; Kotila, J.; Martinez, M.; Nagorny, S.; Nastasi, M.; Nisi, S.; Nones, C.; Orlandi, D.; Pagnanini, L.; Pallavicini, M.; Pattavina, L.; Pavan, M.; Pessina, G.; Pettinacci, V.; Pirro, S.; Pozzi, S.; Previtali, E.; Puiu, A.; Rusconi, C.; Schäffner, K.; Tomei, C.; Vignati, M.; Zolotarova, A. S.

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 the 82Se neutrinoless double β decay, as well as the most precise measurement of the 82Se 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 of 82Se. 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.