We discuss the possibility of observing a loosely bound molecular state in a B three-body hadronic decay. In particular we use the QCD sum rule approach to study a $eta^prime-pi$ molecular current. We consider an isovector-scalar $I^G J^{PC}= 1^-~0^{
++}$ molecular current and we use the two-point and three-point functions to study the mass and decay width of such state. We consider the contributions of condensates up to dimension six and we work at leading order in $alpha_s$. We obtain a mass around 1.1 GeV, consistent with a loosely bound state, and a $eta^prime-pirightarrow K^+ K^-$ decay width around 10 MeV.
We evaluate the non-resonant decay amplitude of the process $B^pmto K^pmpi^+ pi^-$ using an approach based on final state hadronic interactions described in terms of meson exchanges. We conclude that this mechanism generates inhomogeneities in the Dalitz plot of the B decay.
