Limit on the Radiative Neutrinoless Double Electron Capture of $^{36}$Ar from GERDA Phase I

TL;DR

This paper reports a search for neutrinoless double electron capture in argon-36 using GERDA Phase I data, setting a new lower limit on its half-life and contributing to the understanding of neutrino properties.

Contribution

First experimental search for neutrinoless double electron capture in argon-36 with GERDA data, establishing a new lower limit on its half-life.

Findings

No signal observed for neutrinoless double electron capture in $^{36}$Ar.

Established a lower half-life limit of 3.6 x 10^{21} years at 90% confidence.

Provides constraints on lepton number violation and Majorana neutrino theories.

Abstract

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of $^{36}$Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of $^{36}$Ar was established: $T_{1/2} > $ 3.6 $\times$ 10$^{21}$ yr at 90 % C.I.