Semileptonic b-baryon decays within a new physics approach

Abstract

Abstract The excess in the measurement of the branching fractions of $$\bar{B}\rightarrow D(D^*){\tau }^- \bar{\nu }_{\tau }$$ B ¯ → D ( D ∗ ) τ - ν ¯ τ and $$B_{c}\rightarrow J/\psi {\tau }^{-} \bar{\nu }_{\tau }$$ B c → J / ψ τ - ν ¯ τ from the standard model expectation hints the existence of new physics beyond the standard model. Motivated by these indications, we study similar modes mediated by $$b\rightarrow c \tau {\bar{\nu }_{\tau }}$$ b → c τ ν ¯ τ transitions, in particular, the semileptonic b-baryon decay modes $$\varXi _b\rightarrow \varXi _{c} \tau ^- \bar{\nu }_{\tau }$$ Ξ b → Ξ c τ - ν ¯ τ and $$\varSigma _b \rightarrow \varSigma _c^{(*)} {\tau }^- \bar{\nu }_{\tau }$$ Σ b → Σ c ( ∗ ) τ - ν ¯ τ . We consider a general low energy effective Hamiltonian approach, which includes both standard model and new physics contributions. Within different new physics scenarios, we investigate the impact of the new contributions on these modes and present predictions for various semileptonic $$q^2$$ q 2 -spectra.