Lepton Universality Violation by Kaluza-Klein Neutrinos in $b\to sll$ transition

Abstract

Recent measure of $R_K$, involving the decays of $b\to s{l}^{+}{l}^{-}$, by the LHCb at CERN strengthened the deviation from the Standard Model prediction. The best fit in the updated global analysis suggests that the muon specific Wilson coefficients $C_9^{bs\mu \mu }=-C_{10}^{bs\mu \mu }$ should be about $-0.41$. In this paper, we show that the accumulate effects of KK modes of a singlet Dirac neutrino propagating in the large extra-dimensional space naturally provide $C_9^{bsll}=-C_{10}^{bsll}$ to explain the anomaly. By taking the muon Yukawa coupling to be of $\mathcal{O}(1)$, the fundamental scale in the extra-dimensional framework should be lowered down to about $2.9$ TeV if there are two additional spatial dimensions.

Comments: 18 pages, 5 figures