Low-energy probes for Dirac vs. Majorana neutrinos beyond $0\nu\beta\beta$ decay
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With the discovery of the Higgs boson, the last missing piece of evidence confirming the Standard Model (SM) of particle physics has been obtained. However, the observation of neutrino oscillations has established non-vanishing neutrino masses, which are undeniable evidence of physics beyond the SM. Many new phenomena can emerge from various New Physics (NP) constructions beyond the SM explaining neutrino mass, among which one finds processes that violate lepton number, charged lepton flavours, or even the universality of lepton flavours. These rare observables are currently being studied in various high-intensity facilities, and if observed, will indicate a clear sign of New Physics. In this talk, I will mainly focus on low-energy probes complementary to neutrino less double beta decay which can shed light on the Dirac vs. Majorana nature of neutrinos. I will discuss how a radiative upscattering process with a photon emitted in the final state can provide a novel experimental mode to probe neutrino transition magnetic moments beyond existing limits and how the differential distributions for such a radiative mode can also be sensitive to the Dirac vs. Majorana nature of neutrinos. I will also discuss some low-energy lepton flavour violating mesonic and leptonic processes and the conditions under which they can provide valuable insight into Dirac vs Majorana nature of neutrinos.