Correlation between RD() and top quark FCNC decays in leptoquark models

Abstract

Some interpretations of RD anomaly in B meson decay using leptoquark (LQ) models can also generate top quark decays through Flavor Changing Neutral Current (FCNC). In this work we focus on two LQs, i.e. scalar S-1 and vector U-1 which are both singlet under the SU(2)(L) gauge group in the Standard Model (SM). We investigate their implications on the 3-body top FCNC decays t -˃ cl(i)l(j) at tree level and the 2-body t -˃ cV at one-loop level, with l being the SM leptons and V = gamma, Z, g being the SM gauge bosons. We utilize the 2 sigma parameter fitting ranges of the LQ models and find that Br(t -˃ cl(i)l(j)) at tree level can reach O(10(-6)) and Br(t -˃ cV) at one-loop level can reach O(10(-10)). Some quick collider search prospects are also analyzed.