IPA2022: Interplay between Particle and Astroparticle physics 2022

Search for 76Ge 0νββ decay and beyond with the GERDA experiment

8 Sept 2022, 14:20

20m

TU Wien

Contributed Talk Lepton Flavour Physics Lepton Flavour Physics

Speaker

Elisabetta Bossio

Description

Observing the neutrino-less double-beta (0$\nu \beta \beta$) decay would imply that neutrinos have a Majorana mass component and provide evidence of lepton number violation. The Germanium Detector Array (GERDA) experiment searched for 0$\nu \beta \beta$ of ${}^{76}$Ge operating enriched high purity germanium detectors in an instrumented Liquid Argon volume at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. At the end of Phase II, with a total exposure of 127.2 kg$\cdot$yr, no 0$\nu \beta \beta$ decay signal was found, and the most stringent lower limit on the ${}^{76}$Ge 0$\nu \beta \beta$ decay half-life was set at 1.8$\cdot$10${}^{26}$ yr at 90% C.L., coinciding with the median sensitivity for the null hypothesis.
The ultra-low background and excellent understanding of the experiment’s response achieved in GERDA Phase II also allowed a measurement of the Standard Model 2$\nu \beta \beta$ decay half-life of ${}^{76}$Ge with unprecedented precision. It provides essential inputs for nuclear structure calculations that benefit the interpretation of 0$\nu \beta \beta$ decay results. Furthermore, the search for distortions of the 2$\nu \beta \beta$ decay spectrum allows exploring new physics, like 0$\nu \beta \beta$ decay with Majoron emission, Lorentz invariance, or search for sterile neutrinos.
This talk will cover the final result of GERDA on the search for ${}^{76}$Ge 0$\nu \beta \beta$ decay, as well as new results on the ${}^{76}$Ge 2$\nu \beta \beta$ decay half-life and limits on exotic decay modes.

Presentation materials

IPA22_BossioE.pdf