Limit on the radiative neutrinoless double electron capture of ^{36} Ar from GERDA Phase I

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\(^{21}\) years at 90% CI.