Constraints on the parameters of the left-right mirror model

Abstract

We study some phenomenological constraints on the parameters of a left right model with mirror fermions (LRMM) that solves the strong CP problem. In particular, we evaluate the contribution of mirror neutrinos to the invisible Z decay width (Γ inv Z ), and we find that the present experimental value on Γ inv Z , can be used to place an upper bound on the Z-Z ′ mixing angle that is consistent with limits obtained previously from other low-energy observables. In this model the charged fermions that correspond to the standard model (SM) mix with its mirror counterparts. This mixing, simultaneously with the Z-Z ′ one, leads to modifications of the Γ(Z → ff ) decay width. By comparing with LEP data, we obtain bounds on the standard-mirror lepton mixing angles. We also find that the bottom quark mixing parameters can be chosen to fit the experimental values of R b , and the resulting values for the Z-Z ′ mixing angle do not agree with previous bounds. However, this disagreement disappears if one takes the more recent ALEPH data.14.60. St,14.60.Pq,12.15.Ff,10.30.Er,

Ansatz para la Matriz de Masa de los Neutrinos con Fermiones Espejo

“…Adicionalmente, modelos con fermíones espejo, en el contexto de una simetría izquierda-derecha (L-R), [14] dan una solución alternativa al problema de CP fuerte. Entonces es natural considerar la existencia de fermíones espejo.…”

“…La "Ruptura espontánea de la simetría" (SSB) es obtenida siguiendo las etapas: (12) Donde es el grupo de simetría del "Modelo Estándar", y El sector de Higgs, usado para inducir la SSB en la ecuación (12), involucra dos dobletes de campos escalares de Higgs: (13) Donde las entradas corresponden a las propiedades de transformación bajo las simetrías del grupo G, con los "Valores de expectación del vacío" (VEVs) (14) El potencial más general, consistente con la simetría P es: (15) El lagrangeano escalar para el modelo está escrito como: (16) Donde y son las derivadas covariantes, asociadas al SM y a la parte espejo, respectivamente. Las interacciones de norma de los quarks y leptones, pueden ser obtenidas del lagrangeano: (17) Los valores de expectación del vacío v y v ´están relacionados a las masas de los bosones de norma W y , a través de y , con g L y g R siendo las constantes de acoplamiento de…”

New Higgs signals induced by mirror fermion mixing effects

“…In the left-right model with mirror fermions (LRMM) [3], the right-handed (left-handed) components of mirror fermions transform as doublets (singlets) under the new SU(2) R . The SM fermions are singlets under the SU(2) R , whereas the right-handed mirror are also singlets under SU(2) L .…”

“…However this matrix can be diagonalized by an orthogonal transformation R, which relates the weak and mass eigenstates, namely [3] …”

“…In particular, mirror fermions are very interesting objects from a phenomenological point of view, and their low-energy effects have been studied too [1], including a discussion of limits on their masses [2]. More recently, models involving mirror fermions generations, i.e., fermions with "mirror" isospin charges, have been discussed within a left-right (LR) symmetric context [3]. These models offer a possible solution to the strong CP problem, and have also been discussed in the context of strongly-interacting electroweak symmetry breaking scheemes [4,5].…”