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- o r L-violating effects. This result is mainly due to the (almost) conse rved number of right-handed electrons at high temperatures T greater t han or similar to O(10) TeV, but also the mass corrections, in particu lar the thermal masses of leptons which act as the protector of the pr imordial baryon asymmetry.