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Bounding the Number of Light Neutrinos Species in a Left-Right Symmetric Model

A. Gutierrez-Rodriguez·M. A. Hernandez-Ruiz·M. A. Perez·F. Perez-Vargas
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Abstract

Using the experimental values for the rates $R^{LEP} _{exp}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.016$, $R^{Giga-Z_1}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.012$ (most conservative) and $R^{Giga-Z_1}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.006$ (most optimistic) we derive constraints on the number of neutrinos light species $(N_ν)_{LRSM}$ with the invisible width method in the framework of a left-right symmetric model (LRSM) as a function of the LR mixing angle $ϕ$. Using the LEP result for $N_ν$ we may place a bound on this angle, $-1.6\times 10^{-3}\leqϕ\leq 1.1\times 10^{-3}$, which is stronger than those obtained in previous studies of the LRSM.

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A. Gutierrez-Rodriguez, M. A. Hernandez-Ruiz, M. A. Perez, F. Perez-Vargas. 2007-04-08. Bounding the Number of Light Neutrinos Species in a Left-Right Symmetric Model. https://arxiv.org/abs/hep-ph/0702076

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