QCD Factorization for $B\to \pi \pi \ell \nu$ Decays at Large Dipion Masses

Philipp Böer, Thorsten Feldmann, Danny van Dyk

We introduce a factorization formula for semi-leptonic $b\to u$ transitions in the exclusive decay mode $B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\bar{\nu }}_{\ell }$ in the limit of large pion energies and la…