In a world without an axion, the smallness of θ̄ may be achieved due to a spontaneously broken discrete left-right symmetry. We analyze the radiatively induced θ̄ in the context of generic left-right symmetric supersymmetry models without assuming flavor degeneracy in the squark sector. Left-right symmetry allows us to keep θ̄within its present bound only if the intergenerational mass splitting in the squark sector at the scale of the left-right symmetry breaking is smaller than 0.5%. We also consider the naturalness of the mu = 0 solution to the strong CP problem in the context of horizontal flavor symmetries. A strong bound on the combination of the horizontal charges in the up quark sector is found in this case.
|Original language||English (US)|
|Journal||Physical Review D|
|State||Published - 2002|