Split Fermion Scenario Research Articles

Numerical study of leptogenesis in a 5D split fermion model with bulk neutrinos

We study numerically a 5D hybrid model which incorporates a split fermion scenario and bulk neutrinos. We perform a Monte Carlo analysis of the model in order to find the regions in the parameter space allowing for realization of the leptogenesis. We find that higher order Yukawa terms must be included in order the model to produce a CP violation and net baryon number sufficient for the creation of the observed baryon asymmetry of the Universe.

Charged lepton electric dipole moments with localized leptons and new Higgs doublet in the two Higgs doublet model

We study the electric dipole moments of the leptons in the split fermion scenario, in the two Higgs doublet model, where the new Higgs scalars are localized around the origin in the extra dimension, with the help of the localizer field. We observe that the numerical value of the electric dipole moment of the electron (muon, tau) is of the order of the magnitude of 10-31 (10-24, 10-22) (e cm), and this quantity is sensitive to the new Higgs localization in the extra dimension.

THE RADIATIVE LEPTON FLAVOR VIOLATING DECAYS IN THE SPLIT FERMION SCENARIO IN THE TWO-HIGGS DOUBLET MODEL

We study the branching ratios of the lepton flavor violating processes μ→eγ, τ→eγ and τ→μγ in the split fermion scenario, in the framework of the two-Higgs doublet model. We observe that the branching ratios are relatively more sensitive to the compactification scale and the Gaussian widths of the leptons in the extra dimensions, for two extra dimensions and especially for the τ→μγ decay.

Hybrid model of neutrino masses and oscillations: Bulk neutrinos in the split-fermion scenario

Higher-dimensional models of neutrino physics with one or more right-handed neutrinos in the bulk have attracted considerable attention in recent years. However, a critical issue for such models is to find a way of introducing the required flavor dependence needed for generating neutrino oscillations. In this paper, we point out that a natural minimal framework that accomplishes this can be constructed by combining the bulk-neutrino hypothesis for right-handed neutrinos with the split-fermion scenario for left-handed neutrinos. This combination leads to a unique flavor signature for neutrino phenomenology which easily incorporates large flavor mixing angles. This hybrid scenario also has a number of additional important features. For example, one previous difficulty of the split-fermion scenario applied to neutrinos has been that the mass matrix is exponentially sensitive to neutrino displacements within the brane. However, in our hybrid scenario, the interactions between the brane and bulk naturally convert this dependence from exponential to linear. Another important feature is that our hybrid scenario provides its own natural regulator for Kaluza-Klein sums. Thus, in our scenario, all Kaluza-Klein summations are manifestly finite, even in cases with multiple extra dimensions. But most importantly, our mechanism completely decouples the effective neutrino flavor mixing angles from the sizes of the overlaps between the neutrino wave functions within the brane. Thus, we are able to obtain large neutrino mixing angles even when these neutrinos have significant spatial separations and their overlaps vanish.

The effect of the location of the new Higgs doublet on the radiative lepton flavor violating decays in the split fermion scenario

We study the branching ratios of the lepton flavor violating processes \mu -> e\gamma, \tau -> e\gamma and \tau -> \mu\gamma in the split fermion scenario, with the assumption that the new Higgs doublet is restricted to the 4D brane (thin bulk) in one and two extra dimensions, in the framework of the two Higgs doublet model. We observe that the branching ratios are sensitive to the location of the 4D brane and, in the second case, the width of the thin bulk, especially for the \mu -> e\gamma decay.

Lepton flavor violating Z→l1 +l2 - decay in the split fermion scenario in the two Higgs doublet model

We predict the branching ratios of the Z→e±μ±, Z→e±τ± and Z→μ±τ± decays in the framework of the 2HDM, in the split fermion scenario. We observe that the branching ratios are not sensitive to a single extra dimension; however, this sensitivity is considerably large for two extra dimensions.

Confining the electroweak model to a brane

We introduce a simple scenario where, by starting with a five-dimensional $SU(3)$ gauge theory, we end up with several 4-D parallel branes with localized fermions and gauge fields. Similar to the split fermion scenario, the confinement of fermions is generated by the nontrivial topological solution of a $SU(3)$ scalar field. The 4-D fermions are found to be chiral, and to have interesting properties coming from their 5-D group representation structure. The gauge fields, on the other hand, are localized by loop corrections taking place at the branes produced by the fermions. We show that these two confining mechanisms can be put together to reproduce the basic structure of the electroweak model for both leptons and quarks. A few important results are: Gauge and Higgs fields are unified at the 5-D level; and new fields are predicted: One left-handed neutrino with zero-hypercharge, and one massive vector field coupling together the new neutrino with other left-handed leptons. The hierarchy problem is also addressed.

Electric dipole moments of charged leptons in the split fermion scenario in the two Higgs doublet model

We predict the charged lepton electric dipole moments in the split fermion scenario in the framework of the two Higgs doublet model. We observe that the numerical value of the muon (tau) electric dipole moment is at the order of the magnitude of $10^{-22} (e-cm)$ ($10^{-20} (e-cm)$) and there is an enhancement in the case of two extra dimensions, especially for the tau lepton electric dipole moment.