Mainz 2022 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 21: Astroparticle Physics I

HK 21.3: Talk

Monday, March 28, 2022, 17:00–17:15, HK-H10

New results on the ⁷⁶Ge double beta decay with neutrinos and exotic decay modes from GERDA Phase II — •Elisabetta Bossio for the GERDA collaboration — Physik Department, Technische Universität München, Garching, Germany

Two-neutrino double beta (2νββ) decays are amongst the rarest nuclear processes ever observed. Precision studies of the electron sum energies require ultra-low background and an excellent understanding of the experiment’s response. Both are key features of the Germanium Detector Array (GERDA) experiment, which searched for neutrino-less double beta (0νββ) decay with enriched high purity germanium detectors in Liquid Argon at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The measurement of the Standard Model 2νββ decay half-life of ⁷⁶Ge was performed with unprecedented precision, profiting from the high signal-to-background ratio and the small systematic uncertainties. It provides essential inputs for nuclear structure calculations, that benefit the interpretation of 0νββ decay results. Furthermore, the search for distortions of the 2νββ decay spectrum allows exploring new physics, like 0νββ decay with Majorons emission, Lorentz invariance, or search for sterile neutrinos. The new results of the ⁷⁶Ge 2νββ decay half-life and improved limits on exotic decay modes will be presented in this talk. This research is supported by the BMBF through the Verbundforschung 05A20WO2 and by the DFG through the Excellence Cluster ORIGINS and the SFB1258.