Speaker
Description
In this talk, we present studies of two semileptonic decays with two hadrons in the final state. First, we’ll discuss $B \rightarrow D \pi \ell \nu$ decays that not only constitute a sizeable background for $R(D^{(*)})$ determinations, but also comprise a largely unknown signal component for inclusive $B \rightarrow X_{c}\ell \nu$ decays. The dominant decay chain proceeds through resonant $B \rightarrow D^{*}$/$D_{2}^{*}(\rightarrow D\pi)\ell \nu$ decays, but also includes a poorly understood broad component. We study the composition of this broad component by using our newly developed formalism for $B \rightarrow D \pi \ell \nu$ decays, together with experimental spectral measurements, and investigate the plausibility of the two-pole structure in the $D\pi$ S-wave. In addition, we provide recommendations for possible future measurements to systematically improve current understanding of $B \rightarrow D \pi \ell \nu$ decays kinematics.
In the second part of the talk we present new results on $B \rightarrow \pi \pi \ell \nu$ decays, relevant to studies of $B \rightarrow \rho \ell \nu$ and $V_{ub}$ determinations. We discuss the separation of signal P-wave from background S-wave contributions in the $\rho$-region and the use of $e^{+}e^{-} \rightarrow \pi^{+}\pi^{-}$ data to describe the $\rho$-lineshape. In addition, we briefly discuss the inclusion of the leading isospin breaking effects in $B \rightarrow \pi \pi \ell \nu$ decays.
