In GUTs, proton decay could proceed by one of two channels: into either a neutral pion and a positron, or a positive pion and a neutrino. (The experimental limit for the proton's lifetime from the ...

Does the proton decay? While this was a famous prediction of Grand Unified Theories (GUTS) developed in the 1970s and 1980s, experimentalists have ruled it out—or rather, put lower limits on its ...