Correlation between R D ∗ $$ {R}_{D^{\left(\ast \right)}} $$ and top quark FCNC decays in leptoquark models

Abstract

Abstract Some interpretations of R D ∗ $$ {R}_{D^{\left(\ast \right)}} $$ 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 = γ, Z, g being the SM gauge bosons. We utilize the 2σ parameter fitting ranges of the LQ models and find that Br(t → cℓ i ℓ j ) at tree level can reach O $$ \mathcal{O} $$ (10−6) and Br(t → cV) at one-loop level can reach O $$ \mathcal{O} $$ (10−10). Some quick collider search prospects are also analyzed.

Keywords

• Phenomenological Models