Implications of new physics in the decays $B_c \to (J/\psi,\eta_c)\tau\nu$

Understand

We study the semileptonic decays of the $B_c$ meson into final charmonium states within the standard model and beyond.

• The relevant hadronic transition form factors are calculated in the framework of the covariant confined quark model developed by us.
• We focus on the tau mode of these decays, which may provide some hints of new physics effects.
• We extend the standard model by assuming a general effective Hamiltonian describing the $b\to c\tau\nu$ transition, which consists of the full set of the four-fermion operators.