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A. Doff

Publications and source records attributed to A. Doff.

53 records · Page 3Linked to original sources
arXiv2010

Scalar bosons in Minimal and Ultraminimal Technicolor: Masses, trilinear couplings and widths

We compute masses, trilinear self-couplings and decay widths into weak bosons of the scalar composite bosons in the case of the Minimal and Ultraminimal technicolor models. The masses, computed via the Bethe-Salpeter equation, turn out to be light and the trilinear couplings smaller than the one that would be expected when compared to a fundamental Standard Model scalar boson with the same mass. The decay widths into electroweak bosons of the Ultraminimal model scalars bosons are much smaller than the one of the Minimal model.

hep-ph↗
arXiv2009

Light composite Higgs boson from the normalized Bethe-Salpeter equation

Scalar composite boson masses have been computed in QCD and Technicolor theories with the help of the homogeneous Bethe-Salpeter equation (BSE), resulting in a scalar mass that is twice the dynamically generated fermion or technifermion mass ($m_{dyn}$). We show that in the case of walking (or quasi-conformal) technicolor theories, where the $m_{dyn}$ behavior with the momenta may be quite different from the one predicted by the standard operator product expansion, this result is incomplete and we must consider the effect of the normalization condition of the BSE to determine the scalar masses. We compute the composite Higgs boson mass for several groups with technifermions in the fundamental and higher dimensional representations and comment about the experimental constraints on these theories, which indicate that models based on walking theories with fermions in the fundamental representation may, within the limitations of our approach, have masses quite near the actual direct exclusion limit.

hep-ph↗
arXiv2009

Mass and width of a composite Higgs boson

The scalar Higgs boson mass in a Technicolor model was obtained by Elias and Scadron with the analysis of an homogeneous Bethe-Salpeter equation (BSE), however it was performed before the most recent developments of walking gauge theories. It was not observed in their work that dynamically generated technifermion mass may vary according to the theory dynamics that forms the scalar bound state. This will be done in this work and we also call attention that their calculation must change to take into account the normalization condition of the BSE. We compute the width of the composite boson and show how the gauge group and fermion content of a technicolor theory can be inferred from the measurement of the mass and width of the scalar boson.

hep-ph↗
arXiv2009

Walking Behavior in Technicolored GUTs

There exist two ways to obtain walk behavior: assuming a large number of technifermions in the fundamental representation of the technicolor (TC) gauge group, or a small number of technifermions, assuming that these fermions are in higher-dimensional representations of the TC group. We propose a scheme to obtain the walking behavior based on technicolored GUTs (TGUTs), where elementary scalars with the TC degree of freedom may remain in the theory after the GUT symmetry breaking.

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arXiv2008

Light composite Higgs from an effective action for technicolor

We compute an effective action for a composite Higgs boson formed by new fermions belonging to a general technicolor non-Abelian gauge theory, using a quite general expression for the fermionic self-energy that depends on a certain parameter (alpha), that defines the technicolor theory from the extreme walking behavior up to the one with a standard operator product expansion behavior. We discuss the values of the trilinear and quadrilinear scalar couplings. Our calculation spans all the possible physical possibilities for mass and couplings of the composite system. In the case of extreme walking technicolor theories we verify that it is possible to have a composite Higgs boson with a mass as light as the present experimental limit, contrary to the usual expectation of a heavy mass for the composite Higgs boson. In this case we obtain an upper limit for the Higgs boson mass, M_H ~ 700GeV for SU(2)_TC, and the experimental data on the Higgs boson mass constrain SU(N)_TC technicolor gauge groups to be smaller than SU(10)_TC.

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arXiv2007

The Energy Criterion and Dynamical Symmetry Breaking in a $SU(3)_L \otimes U(1)_X$ Extension of the Standard Model

The coupling constants $g_L$ and $g_X$ of some versions of the $SU(3)_L\otimes U(1)_X$ extension of the standard model are related through to relationship $g^2_X/g^2_L= \sin^2θ_W/(1 - 4\sin^2θ_W)$. This fact suggest that the $SU(3)_L\otimes U(1)_X$ gauge symmetry in this class of models can be broken dynamically to the standard model at TeV scale without requiring the introduction of fundamental scalars. This possibility was investigated by Das and Jain who considered only the first version of this class of models. In this brief report we discuss an energy criterion to verify the most probable version of the $SU(3)_L\otimes U(1)_X$ model that is realized in nature.

hep-ph↗
arXiv2006

Spontaneous CP violation in the 3-3-1 model with right-handed neutrinos

We implement the mechanism of spontaneous CP violation in the 3-3-1 model with right-handed neutrinos and recognize their sources of CP violation. Our main result is that the mechanism works already in the minimal version of the model and new sources of CP violation emerges as an effect of new physics at energies higher than the electroweak scale.

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arXiv2005

Strength of the Trilinear Higgs Boson Coupling in Technicolor Models

We discuss the strength of the trilinear Higgs boson coupling in technicolor (or composite) models in a model independent way. The coupling is determined as a function of a very general ansatz for the technicolor self-energy, and turns out to be equal or smaller than the one of the standard model Higgs boson depending on the dynamics of the theory. With this trilinear coupling we estimate the cross section for Higgs boson pair production at the LHC. This measurement is quite improbable in the case of a heavy standard model Higgs boson, but it will be even worse when this boson is dynamically generated.

hep-ph↗
arXiv2005

Neutrino Decay and Neutrinoless Double Beta Decay in a 3-3-1 Model

In this work we show that the implementation of spontaneous breaking of the lepton number in the 3-3-1 model with right-handed neutrinos gives rise to fast neutrino decay with majoron emission and generates a bunch of new contributions to the neutrinoless double beta decay.

hep-ph↗
arXiv2005

A dynamical mechanism to explain the top-bottom quark mass hierarchy

We discuss the mass splitting between the the top and bottom quarks in a technicolor scenario. The model proposed here contains a left-right electroweak gauge group. An extended technicolor group and mirror fermions are introduced. The top-bottom quark mass splitting turns out to be intimately connected to the breaking of the left-right gauge symmetry. Weak isospin violation occurs within the experimental limits.

hep-ph↗
arXiv2004

The origin of the first and third generation fermion masses in a technicolor scenario

We argue that the masses of the first and third fermionic generations, which are respectively of the order of a few MeV up to a hundred GeV, are originated in a dynamical symmetry breaking mechanism leading to masses of the order $αμ$, where $α$ is a small coupling constant and $μ$, in the case of the first fermionic generation, is the scale of the dynamical quark mass ($\approx 250$ MeV). For the third fermion generation $μ$ is the value of the dynamical techniquark mass ($\approx 250$ GeV). We discuss how this possibility can be implemented in a technicolor scenario, and how the mass of the intermediate generation is generated.

hep-ph↗
arXiv2003

Limit on the fermion masses in technicolor models

Recently it has been pointed out that no limits can be put on the scale of fermion mass generation $(M)$ in technicolor models, because the relation between the fermion masses $(m_f)$ and $M$ depends on the dimensionality of the interaction responsible for generating the fermion mass. Depending on this dimensionality it may happens that $m_f$ does not depend on $M$ at all. We show that exactly in this case $m_f$ may reach its largest value, which is almost saturated by the top quark mass. We make few comments on the question of how large can be a dynamically generated fermion mass.

hep-ph↗
arXiv2000

On the color simple group from chiral electroweak gauge groups

Following the pioneering Okubo scrutiny of gauge simple groups for the quantum chromodynamics we show the constraints coming from the wondrous predictive leptoquark-bilepton flavordynamics connecting the number of color charges to solution of the flavor question and to an electric charge quantization unconstrained from the Dirac, Majorana or Dirac--Majorana character of massive neutrino.

hep-ph↗
arXiv2000

Minimal extended flavor groups, matter fields chiral representations, and the flavor question

We show the specific unusual features on chiral gauge anomalies cancellation in the minimal, necessarily 3-3-1, and the largest 3-4-1 weak isospin chiral gauge semisimple group leptoquark-bilepton extensions of the 3-2-1 conventional standard model of nuclear and electromagnetic interactions. In such models a natural explanation for the fundamental question of fermion generation replication arises from the self-consistency of a local gauge quantum field theory, which constrains the number of the QFD fermion families to the QCD color charges.

hep-ph↗
arXiv1998

Charge quantization in the largest leptoquark-bilepton chiral electroweak scheme

The uniqueness of the hypercharge assignments in the three fermion families leptoquark-bilepton $SU(3)_C \times SU(4)_L \times U(1)_N$ model is established. Although the gauge group contains an explicit U(1) factor, freedom from triangle anomalies combined with the requirement of nonvanishing charged fermion masses uniquely fix the electric charges of all fermions independently of the neutrinos being massless or not. The electric-charge quantization, family replication, and the existence of three colors are interwoven.

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