Neutrino mixing and masses in a left-right model with mirror fermions

In the framework of a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$, we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate the decay rates of the Lepton Flavor Violation (LFV) processes $\mu \rightarrow e \gamma$, $\tau \rightarrow \mu \gamma$ and $\tau \rightarrow e\gamma$. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We also estimate the decay rates of heavy Majorana neutrinos in the channels $N \rightarrow W^{\pm} l^{\mp}$, $N \rightarrow Z \nu_{l}$ and $N \rightarrow H \nu_{l}$, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing a symmetric mixing of electron neutrino with muon and tau neutrinos leads to Tri-bimaximal mixing matrix for light neutrinos.Comment: Accepted by European Physical Journal

Neutrino masses and mixing parameters in a left-right model with mirror fermions

In this work we consider a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$. The model has several free parameters which here we have calculated by using the recent values for the squared-neutrino mass differences. Lower bound for the mirror vacuum expectation value helped us to obtain crude estimations for some of these parameters. Also we estimate the order of magnitude of the masses of the standard and mirror neutrinos.Comment: 13 pages, version submitted to European Physical Journal

Lepton mass generation and family number violation mechanism in the SU(6)⊗U(1)SU(6)\otimes U(1) model

Lepton family number violation processes arise in the $SU(6)_L \otimes U(1)_Y$ model due to the presence of an extra neutral gauge boson, Z$'$, with family changing couplings, and due to the fact that this model demands the existence of heavy exotic leptons. The mixing of the standard Z with Z$'$ and the mixing of ordinary leptons with exotic ones induce together family changing couplings on the Z and therefore nonvanishing rates for lepton family number violation processes, such as $Z \to e \bar{\mu}$, $\mu \to ee\bar{e}$ and $\mu \to e\gamma$. Additional contributions to the processes $\mu \to e \gamma$ and $\mu \to ee \bar{e}$ are induced from the mass generation mechanism. This last type of contributions may compete with the above one, depending on the masses of the scalars which participate in the diagrams which generate radiatively the masses of the charged leptons. Using the experimental data we compute some bounds for the mixings parameters and for the masses of the scalars.Comment: 12 pages, Latex, 7 figures. Accepted for publication in Int. Journ. of Mod. Phys.

Social and Economic Analysis of the Production of Maradol Papaya (Carica papaya L.): Case study in the coast of Oaxaca, Mexico

Objective: To analyze social, productive and profitability indicators of the conventional agribusiness that produces Maradol papaya in the Coast region of Oaxaca. Methodology: The present research was perform in the agribusiness “Productores de la Costa Posa Verde, S.P.R. de R.L”, in the period June 2020 to August 2021. Semi-structured interviews to the producer and family members were carried out. The economic analysis was implemented using the methodology of budgets by activities. Results: The studied agribusiness is a family type, managed by the head of the family, who is 47 years old, with a high school education and 35 years of experience in managing papaya cultivation. During the studied period, the production cost was $365,190.01 ha-1. Of the total variable costs, the highest cost per cultivated ha were harvesting (38.2$117,633.6 ha-1 and a profitability of 24.4% were observed, and the equilibrium point was 31,268.86 kg. Conclusions: The papaya agribusiness studied is profitable. In addition, papaya production is an important source of job, it contributes to improving the quality of life of the inhabitants of the region. Keywords: Economic indicators, production cost, production profitability.  Objective: To analyze the social, production, and profitability indicators of a conventional agribusiness producing Maradol papaya in the coastal region of Oaxaca. Methodology: This research was conducted at the agribusiness “Productores de la Costa Posa Verde, S.P.R. de R.L” from June 2020 to August 2021. Semi-structured interviews with the producer and his family were conducted. The economic analysis was done using the activity-based budgeting method. Results: The studied company is a family agribusiness run by the head of the family, a 47-year-old man with a high school education and approximately 35 years of experience in the cultivation of papaya. During the period of study, the production cost was $365,190.01 ha-1. From the total variable costs, the largest expenditures per cultivated ha went to harvesting (38.2$117,633.6 ha-1 was observed, together with a profitability of 24.4%, and an equilibrium point of 31,268.86 kg. Conclusions: This papaya farming agribusiness is profitable. Moreover, papaya farming is an important source of work, which contributes to improving the quality of life among the region’s inhabitants

Signals of extra gauge bosons and exotic leptons in SU(6)L⊗_{L}\otimesU(1)Y_{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 $K^{+}\longrightarrow \pi^{+}\mu^{+}e^{-}$, $K_L^0\longrightarrow \mu^{+}e^{-}$ and $\mu^{-} \longrightarrow e^{-} \bar{\nu_e} \nu_\mu$ 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

New Higgs signals induced by mirror fermion mixing effects

We study the conditions under which flavor violation arises in scalar-fermion interactions, as a result of the mixing phenomena between the standard model and exotic fermions. Phenomenological consequences are discussed within the specific context of a left-right model where these additional fermions have mirror properties under the new SU(2)_R gauge group. Bounds on the parameters of the model are obtained from LFV processes; these results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e, mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.

What Cosmology Can Come From the Broken SU(3) Symmetry of the Three Known Families?

International audienceThe question, why there are three quark-lepton families, cannot find answer inthe Standard model. Extension of the symmetry of the Standard model by localgauge SU(3) symmetry of families involves new physics at high energy scales.Even elusive from direct experimental probes such construction can be tested inthe combination of physical, astrophysical and cosmological signatures, in whichcosmological probes play important role. In the case of chiral local gauge SU(3)H family symmetry such probes not only provided complete test of the model, butalso demonstrated a possibility to describe the physical basis of moderncosmology, involving inflationary models with baryosynthesis and nonbaryonicdark matter. We formulate the programme of studies of cosmological impact ofbroken local gauge vector-like SU(3) F family symmetry