Precision predictions for $B \rightarrow ρτν_τ$ and $B \rightarrow ωτν_τ$ in the SM and beyond

We present new precision predictions for semitauonic decays involving $ρ$ and $ω$ final state mesons. These decay channels offer an interesting orthogonal probe to study the existing B anomalies in semitauonic transitions and are accessible with the Belle II experiment. The predictions are based on combining existing light-cone sum-rule calculations for the form factors with measured experimental spectra from the BaBar and Belle collaborations. This allows us to reliably extrapolate the light-lepton form factor predictions to large values of the four-momentum transfer squared, $q^2$, and in turn to derive precise predictions for $R_ρ$ and $R_ω$, the ratio of the total decay rates of $B \rightarrow ρτν_τ$ and $B \rightarrow ωτν_τ$ for $τ$ final states with respect to light leptons in the SM. In addition, we investigate the impact of all four-fermi operators on the semitauonic $q^2$ spectra and these ratios.

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