Grand-Unified Baryogenesis Checked Against Proton Stability

Grand-unified theories violate baryon number through heavy gauge bosons, and their decays are a classic baryogenesis channel, but the same bosons mediate proton decay, which has never been observed. This paper computes both sides of that tension on one page. The proton lifetime scales as the fourth power of the heavy boson mass: at M_X = 1e15 GeV the estimate is 4.60e+31 years, excluded by the experimental bound of 2.4e34 years; at 1e16 GeV it is 4.60e+35 years, and at 1e17 GeV, 4.60e+39 years. Meeting the bound requires M_X above 4.78e+15 GeV. At an efficiency of 0.1 the decays must carry a CP asymmetry of 9.28e-08 to produce the observed baryon yield. In a bounce history the high production temperature is available on both sides of the bounce, but only expanding-side production escapes subsequent washout and dilution. Computed from stated assumptions, not measured.