Related papers: Gravitational anomaly and fundamental forces
We study the lowest dimensional typical and atypical representations of SU(5/3) superalgebra as a possible unified gauge theory having a natural SU(5) subalgebra with SU(3) extra structure, which will be used to accommodate three…
Using the resolution of the gauge hierarchy problem recently proposed by Randall and Sundrum, we find a natural explanation for the observed fermion masses and mixings of the three Standard Model (SM) generations. Localizing massless SM…
We summarize our recent work on gauge theories with two flavors of fermions in the two-index symmetric representation: SU(2) gauge theory with adjoint fermions, SU(3) with sextets, and SU(4) with ten-dimensional-representation fermions. All…
The Standard Model data suggests the realization of grand unification structures in nature, in particular that of SO(10). A class of string vacua that preserve the SO(10) embedding, are the three generation free fermion heterotic-string…
The Harari-Shupe model for fermions is extended to a topological model which contains an explanation for the observed fact that there are only three generations of fermions. Topological explanations are given for $\beta$-decay and for…
We present the mathematical framework for a unified theory based upon su(1|5). The Lie superalgebra su(1|5) has irreducible representations of dimension 32, in which the 32 fundamental fermions of one generation (leptons and quarks, of left…
Taking the 3-3-1 models (with $SU(3)_c \otimes SU(3)_L \otimes U(1)_Y$ gauge group) as examples, we study that a class of new physics models with extended gauge group could undergo one or several first-order phase transitions associated…
We examine the problem of constructing three generation free fermionic string models with grand unified gauge groups. We attempt the construction of $G\times G$ models, where $G$ is a grand unified group realized at level 1. This structure…
We develop an approach to the origin of three generations of the Standard Model fermions from one generation in a higher-dimensional theory, where four-dimensional fermions appear as zero modes trapped in the core of a topological defect,…
The problem of families, "Why are there three families of fermions?", is a long awaited question to be answered within a reasonable framework. We propose anti-SU($N$) groups for the unification of families in grand unification (GUT) groups,…
One of the most important and unanswered problems in particle physics is the origin of the three generations of quarks and leptons. The standard Model does not provide any hint regarding its sequential charge assignments, which remain a…
We discuss an anthropic explanation of why there exist three generations of fermions. If one assumes that the right-handed neutrino sector is responsible for both the matter-antimatter asymmetry and the dark matter, then anthropic selection…
Supersymmetric grand unification based on $SO(10)$ is one of the most attractive paradigms in physics beyond the Standard Model. Inspired by the recent NANOGrav signal, we discuss the implications of detecting a stochastic gravitational…
We formulate an $SU(8)$ family unification model motivated by requiring that the theory should incorporate the graviton, gravitinos, and the fermions and gauge fields of the standard model, with boson--fermion balance. Gauge field $SU(8)$…
Recently a promising mechanism for supersymmetry breaking that utilizes both an anomalous U(1) gauge symmetry and an effective mass term m ~ 1TeV of certain relevant fields has been proposed. In this paper we examine whether such a…
We study two 3-3-1 models with i) five (four) charge 2/3 ($-1/3$) quarks and, ii) four (five) charge 2/3 ($-1/3$) quarks and a vector-like third generation. Possibilities beyond these models are also briefly considered.
The reasons behind the gauge symmetry of the Standard Model, U(1)xSU(2)xSU(3), are still unsettled. One obvious feature is the low dimensionality of all its subgroups. Under certain conditions, a negative answer to the question "why not…
We prove that global anomaly cancellation requires more than one generation of quarks and leptons, provided that the standard model fields propagate in two universal extra dimensions. Furthermore, if the fermions of different generations…
We investigate a local $SU(3)_F$ flavour symmetry for its viability in generating the masses for the quarks and charged leptons of the first two families through radiative corrections. Only the third-generation fermions get tree-level…
SU(3) gauge theory coupled to N_f = 2 fermions in the sextet representation is a promising candidate for a technicolor inspired Standard Model extension. In this note the progress in the past few years aimed at understanding the…