R-parity violating enhancement of B_u⁺ → ℓ⁺nu; and B_c⁺ → ℓ⁺ν

We study the decays B_u⁺ → ℓ⁺ν and B_c⁺ → ℓ⁺ν in the context of the Minimal Supersymmetric Standard Model (MSSM) with explicit R-parity violation. We analyse the correlation between the two decays and show that branching ratios (BRs) for B_c⁺ → ℓ⁺ν may be of order 5% (over 40% in one case), without violating current bounds on B_u⁺ → ℓ⁺ν. Although B_c mesons are inaccessible at the e⁺e^- B factories, such large BRs for B_c⁺ → ℓ⁺ν would possibly be within experimental observability at LEP and the Tevatron Run II, with much larger yields expected at the hadronic B factories. We also update some earlier bounds on products of R-parity violating couplings in the light of new experimental results.