Study of the semileptonic decays Υ(1S)→B(c)ℓν̄ℓ

We study the exclusive semileptonic decays Υ(1S) → B(c)ℓν̄ℓ, where ℓ = e,µ,τ. The relevant hadronic form factors are calculated using the covariant confined quark model developed previously by our group. We predict the branching fractions B(Υ(1S) → B(c)ℓν̄ℓ) to be of the order of 10−13 and 10−10 for the case of B and Bc, respectively. Our predictions agree well with other theoretical calculations. We also consider the effects of possible new physics in the case of Υ(1S) → Bcτν̄τ and show that the branching fraction of this decay can be enhanced by an order of magnitude using constraints from the B→ D(∗)ℓν̄ℓ and Bc → J/ψℓν̄ℓ experimental data.