Light - cone distribution functions for B decays at subleading order in 1 / m b

We construct the higher twist structure functions that describe inclusive b hadron decays in regions of phase space where the hadronic decay products carry high energy but have low invariant mass. We show that, for B meson decays, there are four new non-vanishing matrix elements of non-local operators. We show that to subleading twist these decays are parametrized in terms of four functions. We compute the tree-level matching for a general heavy-to-light current and apply it to B̄ → Xsγ. Using a simple model for these functions we estimate the subleading twist contributions to this decay.