Testing Lepton Nonuniversality in b→ cτν¯l Decay Modes

We present a model-independent analysis of B→ D(∗ )τν¯l and Bc→ (ηc, J/ ψ) τν¯l processes involving b→ cτν¯l quark-level transitions by considering the most general effective Lagrangian in the presence of new physics. We perform a global fit to various sets of new coefficients, including the measurement on RD(∗), RJ / ψ and the upper limit on Br(Bc→ τνl ). We then show the implication of constrained new couplings on the lepton nonuniversality ratios of these decay modes in bins of q2. © 2021, Springer Nature Singapore Pte Ltd