arXiv subjects

Arnulfo Zepeda

Publications and source records attributed to Arnulfo Zepeda.

12 recordsLinked to original sources

arXiv1999

Nonsupersymmetric gauge coupling unfication in [SU(6)]$^4\times$ Z$_4$ and proton stability

We systematically study the three family extension of the Pati-Salam gauge group with an anomaly-free single irreducible representation which contains the known quarks and leptons without mirror fermions. In the context of this model we implement the survival hypothesis, the modified horizontal survival hypothesis, and calculate the tree level masses for the gauge boson and fermion fields. We also use the extended survival hypothesis in order to calculate the mass scales using the renormalization group equation. The interacting Lagrangean with all the known and predicted gauge interactions is explicitly displayed. Finally the stability of the proton in this model is established.

hep-ph↗

arXiv1998

Non SUSY Unification in Left-Right Models

We explore in a model independent way the possibility of achieving the non supersymmetric gauge coupling unification within left-right symmetric models, with the minimal particle content at the left-right mass scale which could be as low as 1 TeV in a variety of models, and with a unification scale M in the range $10^5$ GeV $< M< 10^{17.7}$ GeV.

hep-ph↗

arXiv1998

Non SUSY and SUSY one--step Unification

We explore the possibility of achieving one--step unification of the standard model coupling constants within non supersymmetric and supersymmetric gauge models, which at low energies have only the standard particle content. The constraints are the experimental values of $α_{em}$, $α_s$ and $\sin^2θ_W$ at $10^2 GeV$, and the lower bounds for FCNC and proton decay rates. The analysis is done in a model independent way.

hep-ph↗

arXiv1997

Symmetry Breaking in $[SU(6)]^3\times Z_3$

We analize the different ways for the spontaneous breaking of the gauge symmetry, for the $[SU(6)]^3\otimes Z_3$ family unification model. In particular we study the consequences of a previous selection for the vacuum expectation values of the Higgs fields, showing that such set predicts unwanted flavor changing neutral currents at the $m_Z=91 GeVs$ mass scale. A new set of vacuum expectation values which solves this problem is proposed.

hep-ph↗

arXiv1997

One Step Non SUSY Unification

We show that it is possible to achieve one step gauge coupling unification in a general class of non supersymmetric models which at low energies have only the standard particle content and extra Higgs fields doublets. The constraints are the experimental values of $α_{em}$, $α_s$ and $\sin^2θ_W$ at $10^2 GeVs$, and the lower bounds for FCNC and proton decay rates. Specific example are pointed out.

hep-ph↗

arXiv1996

Model independent analysis of the simultaneous mixing of gauge bosons and mixing of fermions

We discuss the case of simultaneous mixing of gauge bosons and mixing of fermions in a model independent way and for a variety of extra-fermion representations. In this context we analyze a class of lepton family violating processes, namely Z --> e tau, Z --> mu tau, Z --> e mu, mu --> e e e, tau --> e e e, tau --> mu mu mu, tau --> e mu mu and tau --> mu e e in the presence of one extra neutral gauge boson, Z', with universal, non-universal or family changing couplings. We derive bounds on the combined effect of Z-Z' mixing and ordinary--exotic lepton mixing.

hep-ph↗

arXiv1996

Systematic Study of Horizontal Gauge Theories

We analyze all the possible continuous horizontal gauge groups G_H in relation with their possibility to explain m_b<<m_t. We assume that the only effective fermionic degrees of freedom correspond to the known fermions but allow the possibility of adding a right handed neutrino to each family. We assume that the Higgs fields which generate masses for these fermions, trough renormalizable Yukawa couplings, transform as an irreducible representation of SU(3)_c\otimesSU(2)_L\otimesU(1)_Y\otimesG_H. Under these assumptions we find two U(1)_H or U(1)_{H1}\otimesU(1)_{H2} models free of anomalies and able to guarantee that only the top has a renormalizable mass-generating Yukawa coupling.

hep-ph↗

arXiv1995

Is U(1)$_H$ a Good Family Symmetry?

We analyze U(1)$_H$ as a horizontal symmetry and its possibilities to explain the known elementary-fermion masses. We find that only two candidates, in the context of SU(3)$_c\otimes$SU(2)$_L\otimes$U(1)$_Y\otimes$U(1)$_H$ nonsupersymmetric, are able to fit the experimental result m$_b<<$m$_t$.

hep-ph↗

arXiv1995

A [SU(6)]$^4$ FLAVOR MODEL WITHOUT MIRROR FERMIONS

We introduce a three family extension of the Pati-Salam model which is anomaly-free and contains in a single irreducible representation the known quarks and leptons without mirror fermions. Assuming that the breaking of the symmetry admits the implementation of the survival hypothesis, we calculate the mass scales using the renormalization group equation. Finally we show that the proton remains perturbatively stable.

hep-ph↗

arXiv1995

Signals of extra gauge bosons and exotic leptons in SU(6)$_{L}\otimes$U(1)$_{Y}$

We study some of the consequences of the SU(6)$_{L}\otimes$U(1)$_{Y}$ model of unification of electroweak interactions and families with a horizontal gauge group SU(2)$_{H}$, paying special attention to processes with flavor changing neutral currents. We compute at tree level the decays $K^{+}\longrightarrow π^{+}μ^{+}e^{-}$, $K_L^0\longrightarrow μ^{+}e^{-}$ and $μ^{-} \longrightarrow e^{-} \bar{ν_e} ν_μ$ from which we obtain lower bounds for the mass of the horizontal gauge boson associated with FCNC. Finally we obtain limits on the mixing between ordinary and exotic charged leptons.

hep-ph↗

arXiv1993

Mass Scales and Stability of the Proton in [SU(6)]$^{3}\times$Z$_{3}$

We proof that the proton is stable in the left-right symmetric gauge model [SU(6)]$^3\times$Z$_3$, which unifies nongravitational forces with flavors, broken spontaneously by a minimal set of Higgs Fields and Vacuum Expectation Values down to SU(3)$_{c}\otimes$U(1)$_{EM}$\hspace{0.2cm} . We also compute the evolution of the gauge coupling constants and show how agreement with precision data can be obtained.

hep-ph↗

arXiv1992

The Generational Seesaw Mechanism in [SU(6)]$^{3}\times$Z$_{3}$}

In the context of the left-right symmetric gauge group [SU(6)]$^3\times$ Z$_3$ which unifies nongravitational forces with flavors, we analyze the generational seesaw mechanism. At tree level we get m$_{ν_τ}\sim$m$_{ν_μ}\sim$M$^2_L$/M$_H$, m$_{ν_e}=0$, where M$_L\sim10^2$ GeVs and M$_H\ge 100$ TeVs is the mass scale at which the horizontal interactions get spontaneously broken. The right handed neutrinos get a Majorana mass M$_R\gg $M$_H$ of the order of the scale where SU(2)$_R$ is broken. An exotic neutral lepton with a mass of the order of M$^2_H$/M$_R$ is predicted. First order radiative corrections will produce m$_{ν_e}\neq0$ which is at least two orders of magnitude smaller than the other two neutrino masses.

hep-ph↗