Primordial Baryon Asymmetry and Sphalerons

I show that a cosmological baryon asymmetry generated at the GUT scale is in general safe against washout due to sphalerons and generic $B$- or $L$-violating effects. This result is mainly due to the (almost) conserved number of right-handed electrons at high temperatures $T \gsim {\cal O}(10) $ TeV, but also the mass corrections, in particular the thermal masses of leptons act as the protector of the primordial baryon asymmetry.