Flavor Structure of E_6 GUT Models(Particles and Fields)

概要

論文の詳細を見る
In E_6 grand unified theory with SU(2)_H family symmetry, the spontaneous CP violation can solve the supersymmetric CP problem. The scenario predicts V_<ub>〜O(λ^4) instead of O(λ^3), which is the naively expected value, because of cancellation at the leading order. Since the experimental value of V_<ub> is O(λ^4), it is important to consider the reason and the conditions for the cancellation. In this paper, we provide a simple reason for the cancellation and show that in some E_6 models, such cancellation requires that the vacuum expectation value (VEV) of the adjoint Higgs does not break U(1)_<B-L>. Note that the direction of the VEV plays an important role in solving the doublet-triplet splitting problem by the Dimopoulos-Wilczek mechanism. In this E_6 model, the direction of the adjoint Higgs VEV can be measured experimentally by measuring the size of V_<ub>〜O(λ^4)
2010-06-25