However, this view has been challenged by theories1 that can overcome some of the limitations of the standard model.
Majorana neutrinos mediate a type of nuclear decay called neutrinoless double-β decay, an example of which is neutrinoless double electron capture.
A crucial step towards observing this decay is to detect its standard-model equivalent: two-neutrino double electron capture.
All known interactions in the Universe are mediated by one of four forces: electromagnetic, gravitational, strong or weak.
The electromagnetic force and gravitational force, which we encounter in daily life, are long-range and can act over large distances.
However, it can decay with an extremely long half-life to a tellurium-124 atom, through a process known as two-neutrino double electron capture.
The measured two-neutrino double electron capture will help to test the various nuclear models8 that are used to calculate rates of double-β decay. »