Baryon and lepton number assignment in E6 models.

In E6 models there are new particles whose baryon number is not uniquely assigned. We point out that the baryon and lepton number assignment to these particles can change the baryogenesis scenario significantly. We consider left-right symmetric extension of the standard model in which (B − L) quantum number is gauged. The identification of (B − L) with a generator of E6 is used to define the baryon and lepton numbers for the exotic particles in a way that the electroweak baryon and lepton number anomaly corresponding to the SU(2)L group vanishes, i.e., there is no non-perturbative baryon or lepton number violation during the electroweak phase transition. We study some consequences of the new assignment. 1 On sabbatical leave from Theory Group, Physical Research Laboratory, Ahmedabad 380009, India. On leave from Physics Department, Niigata University, Niigata 950-21, Japan