Determining the weak phase γ in the presence of rescattering

We suggest a new technique to determine the CKM phase gamma without neglecting the (soft) final state rescattering effects. We use (time integrated) B meson decay rates to pi's and K's. A set of five Delta S = 0 (or one Delta S = 0 and four Delta S = 1) decay rates is used to compute the strong phases and magnitudes of the tree level and penguin contributions as functions of gamma. These are used to pl edict a Delta S = 1 (Delta S = 0) B-d/s decay rate as a function of gamma (using SU(3) symmetry). The measurement of this decay rate then gives gamma. We illustrate this technique using different cases. Most of the decay modes we use are expected to be accessible at the B-factories (e(+)e(-) or hadron machines). (C) 1999 Elsevier Science B.V. All rights reserved.