Related papers: New Vector-Like Fermions and Flavor Physics
We derive new constraints on light vectors coupled to Standard Model (SM) fermions, when the corresponding SM current is broken by the chiral anomaly. Cancellation of the anomaly by heavy fermions results, in the low-energy theory, in…
We introduce two anomaly free versions of Froggatt-Nielsen (FN) models, based on either $G_{\rm FN}=U(1)^3$ or $G_{\rm FN}=U(1)$ horizontal symmetries, that generate the SM quark and lepton flavor structures. The structure of these…
We consider a Randall-Sundrum model in which the Standard Model fermions and gauge bosons correspond to bulk fields. We show how the observed charged fermion masses and CKM mixings can be explained, without introducing hierarchical Yukawa…
Arguments coming from Quantum Field Theory are supplemented with a 1-loop perturbative calculation to settle the non-unitarity of mixing matrices linking renormalized mass eigenstates to bare flavor states for non-degenerate coupled…
We show how any flavour conserving $Z'$ model can be made flavour violating and non-universal by introducing mass mixing of quarks and leptons with a fourth family of vector-like fermions with non-universal $Z'$ couplings. After developing…
We define a new class of $Z'$ models with neutral flavor-changing interactions at tree level in the down-quark sector. They are related in an exact way to elements of the quark mixing matrix due to an underlying flavored $U(1)'$ gauge…
We built an extended 2HDM theory with a spontaneously broken $U(1) _{X}$ global symmetry, where the tree level Universal Seesaw Mechanism generates the mass hierarchy of the Standard Model charged fermions and the Zee-Babu mechanism…
Many theories beyond the standard model (BSM) contain new CP-odd and CP-even neutral scalars $\phi = \{A,H\}$, and new vector-like fermions ($\psi_{VL}$). The couplings of the CP-odd scalar $A$ to two standard model (SM) gauge bosons cannot…
With a modest revision of the mass sector of the Standard Model, the systematics of the fermion masses and mixings can be fully described and interpreted as providing information on matrix elements of physics beyond the Standard Model. A…
We study the phenomenology of new heavy vector-like fermions that couple to the third generation quarks via Yukawa interactions, covering all the allowed representations under the standard model gauge groups. We first review tree and loop…
We study the charged Higgs couplings to fermions in the "democratic" three-Higgs-doublet model, in which one doublet couples to down-type quarks, one to up-type quarks, and one to charged leptons. Flavor-changing neutral Higgs couplings are…
We suggest a novel approach towards resolving the fermion mass hierarchy problem within the framework of the Standard Model. It is shown that the observed masses and mixings can be explained with order one couplings using successive higher…
Flavor mixings together with fermion mass spectra are studied in detail in the $SU(6) \times SU(2)_R$ model, in which state-mixings beyond the minimal supersymmetric standard model (MSSM) take place. Characteristic patterns of fermion…
We propose a model of fermion masses and mixings based on $SU(5)$ grand unified theory (GUT) and a $D_{4}$ flavor symmetry. This is a highly predictive 4D $SU(5)$ GUT with a flavor symmetry that does not contain a triplet irreducible…
A grand unified $SU(5)$ theory is constructed with a hierarchical breaking of a $U(2)$ flavor symmetry. The small parameters of the squark and slepton mass matrices, necessary to solve the supersymmetric flavor-changing problem, and the…
Using an effective Lagrangian approach we analyze a generic Higgsless model with composite heavy fermions, transforming as SU(2)_{L+R} Doublets. Assuming that the Standard Model fermions acquire mass through mixing with the new heavy…
In a large class of supersymmetric SO(10) and left-right models, requiring that the effective theory below the scale of $SU(2)_R$ breaking be the MSSM implies partial Yukawa unification with $Y_u=Y_d$ and $Y_e=Y_{\nu^D}$. The same result…
We discuss a model in which the third generation fermions undergo a different $SU(2)$ weak interaction from the first two generation fermions. In general, a flavor changing neutral current interaction is expected. Constrained by the…
We propose a 3+1 Higgs Doublet Model based on the $\Delta(27)$ family symmetry supplemented by several auxiliary cyclic symmetries leading to viable Yukawa textures for the Standard Model fermions, consistent with the observed pattern of…
In this paper we present an in-depth analysis of a recently proposed Standard Model extension with a complete fourth generation of quarks and leptons, which are vector-like with respect to the Standard Model gauge group and charged under a…