Abstract
We study leptonic $CP$ and flavor violations in supersymmetric grand unified theory with right-handed neutrinos, paying attention to the renormalization group effects on the slepton mass matrices due to the neutrino and grand unified theory Yukawa interactions. In particular, we study in detail the impacts of the so-called Casas-Ibarra parameters on $CP$ and flavor violating observables. The renormalization group effects induce $CP$ and flavor violating elements of the supersymmetric breaking scalar mass squared matrices, which may result in sizable leptonic $CP$ and flavor violating signals. Assuming a seesaw formula for the active neutrino masses, the renormalization group effects have been often thought to be negligible as the right-handed neutrino masses become small. With the most general form of the neutrino Yukawa matrix, i.e., taking into account the Casas-Ibarra parameters; however, this is not the case. We found that the maximal possible sizes of signals of leptonic $CP$ and flavor violating processes are found to be insensitive to the mass scale of the right-handed neutrinos and that they are as large as (or larger than) the present experimental bounds irrespective of the right-handed neutrino masses.
Highlights
Even though the standard model (SM) of particle physics successfully explains many of results of high energy experiments, the existence of a physics beyond the SM (BSM) has been highly anticipated
We have studied the leptonic CP and flavor violating observables, i.e., the electron electric dipole moment (EDM) de and the branching rations of lepton flavor violating decays Brðli → ljγÞ, in the minimal supersymmetric SU(5) grand unified theory (GUT) with three righthanded neutrinos
In SUSY models, the off-diagonal elements of the slepton mass matrices are induced by renormalization group effects in particular when there exist right-handed neutrinos with sizable neutrino Yukawa couplings or when quarks and leptons are unified into same multiplets of GUT
Summary
Even though the standard model (SM) of particle physics successfully explains many of results of high energy experiments, the existence of a physics beyond the SM (BSM) has been highly anticipated. We pay particular attention to SUSY SU(5) GUT with right-handed neutrinos, in which superparticle masses are much above the TeV scale, because (i) with the particle content of the minimal SUSY standard model, the gauge coupling unification at MGUT ∼ Oð1016Þ GeV is suggested, and because (ii) right-handed neutrinos are well motivated to explain the origin of the active neutrino masses via the seesaw mechanism [13,14,15]. It has been pointed out that, even if the MSSM particles are out of the reach of the LHC experiment, the signal of the MSSM may be observed by ongoing or future CP or flavor violation experiments.
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