Abstract
We investigate lepton flavor violation in the context of intersecting D-brane models. We point out that these models have a source to generate flavor violation in the trilinear scalar couplings while the geometry of the construction leads to degenerate soft scalar masses for different generations (as in the minimal supergravity model) at the string scale. The trilinear scalar couplings are not proportional to the Yukawa couplings when the F -term of the U -moduli contribution is non-zero. Consequently, the lepton flavor violating decay processes are generated. Only other sources of flavor violations in this model are the Dirac neutrino Yukawa coupling and the Majorana couplings. The observed fermion mixings are realized from the “almost rank 1” Yukawa matrices, which generate a simple texture for the trilinear scalar terms. We calculate the branching ratios of τ → μ γ , μ → e γ and the electric dipole moment of the electron in this model. We find that the observation of all the lepton flavor violating decay processes and the electric dipole moment will be able to sort out different flavor violating sources.
Highlights
The standard model is well established to describe physics below the weak scale while it has a number of parameters, especially in the flavor sector
One expects that there exists more fundamental physics beyond the standard model and the masses and the mixings are described by some fundamental parameters
The values different from what has be shown for the neutrino Dirac Yukawa couplings do not change the plot very much since the chargino diagram does not contribute to the electric dipole moment (EDM)
Summary
The standard model is well established to describe physics below the weak scale while it has a number of parameters, especially in the flavor sector. The Yukawa matrices are written in the factorized form yij = xLi xRj [9, 13] This originates from a geometrical reason that the left- and the right-handed fermions are replicated at the intersecting points on different tori, and the Yukawa couplings are given as an exponential form of sum of the triangle areas. We emphasize the degeneracy of the SUSY breaking mass terms and the U-moduli contribution of the trilinear scalar couplings These contributions are related to the flavor violation and we will study the lepton flavor violation (LFV) processes since the flavor violation in the lepton sector produce much more stringent constraint rather than in the quark sector. In the intersecting D-brane models, the flavor degeneracy of the slepton masses at the cutoff scale is realized naturally and the U-moduli contribution of A-terms can be one of the major sources of flavor violation.
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