Related papers: Limit on the fermion masses in technicolor models
The Schwinger model (QED_2) with N flavors of massive fermions on a circle of circumference L, or equivalently at finite temperature T, is reduced to a quantum mechanical system of N-1 degrees of freedom. With degenerate fermion masses (m)…
The presence of a heavy fermion doublet of fourth generation in the standard model would lead to a anomalous decay with fermion number non-conservation. The anomalous decay path in the background of the electroweak instanton is demonstrated…
Present limits on chiral fourth-generation quark masses $m_{b'}$ and $m_{t'}$ are broadly generalized and strengthened by combining both $t'$ and $b'$ decays and considering the full range of $t'$ and $b'$ flavor-mixing scenarios (with the…
The fermion mass problem is briefly reviewed. The observed hierarchy of quark and charged lepton masses strongly suggests the existence of an approximately conserved chiral flavour symmetry beyond the Standard Model. It is argued that in…
We present a simple model for fermion mass matrices and quark mixing in the context of supersymmetric grand unified theories and show its agreement with experiment. Our model realizes the GUT mass relations $m_d=3m_e$, $m_s= m_\mu/3$,…
The minimal coupling of massless fermions to gravity does not allow for their gravitational production solely based on the expansion of the Universe. We argue that this changes in presence of realistic and potentially detectable stochastic…
The dynamical generation of a fermion mass is studied within ($2+1$)-dimensional QED with $N$ four-component fermions in the leading and next-to-leading orders of the 1/N expansion. The analysis is carried out in the Landau gauge which is…
Flavor transitions via the charged current interactions are parametrized by a three dimensional and unitary transformation. This so called mixing matrix requires of four mixing parameters. Here we show that under the phenomenological…
We study massive spin-1/2 fermion production in nonsingular superstring cosmology, taking into account one-loop quantum corrections to a superstring effective action with dilaton and modulus fields. While no creation occurs in the massless…
Theories that support dynamical generation of a fermion mass gap are of widespread interest. The phenomenon is often studied via the Dyson-Schwinger equation (DSE) for the fermion self energy; i.e., the gap equation. When the rainbow…
We show that composite fermions with masses much smaller than the scale of confinement arise naturally in certain models which admit dynamical breakdown of chiral symmetry. The models are such that to leading order some of the fermions…
We consider the quantum Brayton cycle, constructed from non-interacting fermions, trapped in a one-dimensional box. The work and heat in this cycle are calculated from the expectation values of the Hamiltonian. We analytically calculated…
We consider a system of many fermionic tachyons coupled to a scalar, pseudoscalar, vector and pseudovector fields. The scalar and pseudoscalar fields are responsible for the effective mass, while the pseudovector field is similar to…
We study the effect of bulk fermions on electroweak precision observables in a recently proposed model with warped extra dimensions and no custodial symmetry. We find that the top-quark mass, together with the corrections to the Zbb vertex…
The rate for the production of massive fermions radiated off a pair of massless fermions is calculated analytically. Combined with the analytic calculation of the corresponding virtual contribution one obtains the order $\alpha^2$…
An unconventional Cosmographical model for a generation of fermion and week boson masses without electro-weak Higgs bosons is outlined. It is based on a rich, non perturbative vacuum structure taken to be an object of qualitative…
The trilinear self-coupling of the Higgs boson, in a theory in which this boson is composite, is compared to the experimental bound of this quantity obtained by the CMS experiment. In the case of a model where technicolor (TC) is coupled to…
We investigate a strongly U(1) gauge theory with fermions and scalars on a three dimensional lattice and analyze whether the cintinuum limit might be a renormalizable theory with dynamical mass generation. Most attention is paid to the weak…
Using the recent limits established by ATLAS to the contact four-fermion interaction, bounds on the size of the extra dimensions of space-time have been found, by assuming that the contact interactions come through the inclusion of torsion…
Properties of amplitudes that describe radiative corrections in a bag of heavy fermions bound by the Higgs boson exchange are studied. Classes of amplitudes, in which the large fermion mass is canceled out and hence produces no enhancement…