| Summary: | 碩士 === 國立臺灣大學 === 物理研究所 === 103 === The Standard model(SM), described by the gauge theory SU(3)_c x SU(2)_L x U(1)_Y, is the most successful theory to describe most of the gravity-unrelated phenomena in the nature so far. However, there are still some issues which are unable to be explained by the SM. For examples, the CP violation source from the SM cannot explain the baryon asymmetry of the universe. Furthermore, the current upper bound of
leptonic flavor changing neutral current(FCNC) is significantly order of magnitude larger than the prediction of the SM. These provide us a sensitive window of probing new physics.
On the other hand, the cosmological observations of the nonbaryonic dark matter also cannot be described by the SM field contents. The existence of these dark matter also provide a specific direction of extending the SM. In this thesis, I will focus on these issues under the framework of minimal flavor violaiton(MFV).
In the first part, We explore realizations of MFV for leptons in the simplest seesaw
models where the neutrino mass generation mechanism is driven by new fermion singlets (type I)
or triplets (type III) and by a scalar triplet (type II). We also discuss similarities and
differences of the MFV implementation among the three scenarios.
We consider a number of effective dimension-six
operators constructed by symmetry requirements and study the phenomenological implications,
including flavor-violating rare decay of charged leptons, muon-electron conversion in nuclei, the anomalous magnetic moments, and their electric dipole moments. We evaluate constraints on the scale of MFV associated with these operators from the latest experimental data.
In the second part, we explore scalar dark matter (DM) that is part of a lepton flavor triplet satisfying
symmetry requirements under type-I seesaw model.
The DM candidate couples to standard-model particles via Higgs-portal renormalizable
interactions as well as to leptons through dimension-six operators, all of which have minimal
flavor violation built-in.
We consider restrictions on the new scalars from the Higgs boson measurements, observed relic
density, DM direct detection experiments, and searches for flavor-violating lepton decays.
The viable parameter space can be tested further with future data.
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