# Tree-level lepton universality violation in the presence of sterile neutrinos: impact for $R_K$ and $R_\pi$

Abstract : We consider a tree-level enhancement to the violation of lepton flavour universality in light meson decays arising from modified $W \ell \nu$ couplings in the standard model minimally extended by sterile neutrinos. Due to the presence of additional mixings between the active (left-handed) neutrinos and the new sterile states, the deviation from unitarity of the leptonic mixing matrix intervening in charged currents might lead to a tree-level enhancement of $R_{P} = \Gamma (P \to e \nu) / \Gamma (P \to \mu \nu)$, with $P=K, \pi$. We illustrate these enhancements in the case of the inverse seesaw model, showing that one can saturate the current experimental bounds on $\Delta r_{K}$ (and $\Delta r_{\pi}$), while in agreement with the different experimental and observational constraints.
Document type :
Journal articles
Journal of High Energy Physics, Springer, 2013, 1302, pp.048. <10.1007/JHEP02(2013)048>

https://hal.archives-ouvertes.fr/hal-00752375
Contributor : Patricia Dubois-Violette <>
Submitted on : Thursday, November 15, 2012 - 3:29:29 PM
Last modification on : Wednesday, July 27, 2016 - 2:48:48 PM

### Citation

A. Abada, D. Das, A. M. Teixeira, A. Vicente, C. Weiland. Tree-level lepton universality violation in the presence of sterile neutrinos: impact for $R_K$ and $R_\pi$. Journal of High Energy Physics, Springer, 2013, 1302, pp.048. <10.1007/JHEP02(2013)048>. <hal-00752375>

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