We propose a novel strategy to test lepton flavor universality (LFU) in top decays, applicable to top pair production at colliders. Our proposal exploits information in kinematic distributions and mostly hinges on data-driven techniques, thus having very little dependence on our theoretical understanding of top pair production. Based on simplified models accommodating recent hints of LFU violation in charged current B meson decays, we show that existing LHC measurements already provide non-trivial information on the flavor structure and the mass scale of such new physics (NP). We also project that the measurements of LFU in top decays at the high-luminosity LHC could reach a precision at the percent level or below, improving the sensitivity to LFU violating NP in the top sector by more than an order of magnitude compared to existing approaches.

The Journal of High Energy Physics
Department of Physics

Kamenik, J.F. (Jernej F.), Katz, A. (Andrey), & Stolarski, D.J. (2019). On lepton flavor universality in top quark decays. The Journal of High Energy Physics, 2019(1). doi:10.1007/JHEP01(2019)032