SEARCH FOR THE ANGLE-GAMMA IN THE ELECTROWEAK PENGUIN DOMINATED DECAY B-S-]PI-0-PHI

We point out that due to the isospin symmetry of strong interactions, QCD penguins do not contribute to B(s) --> pi0PHI. However, since the current-current amplitude A(CC) is both CKM- and colour-suppressed, the electroweak penguin contribution A(EWP) becomes important and even dominant. The CP asymmetry A(CP) arising in B(s) --> pi0PHI is expressed as a function of x = A(EWP)/A(CC) and of the angle gamma = -arg(V(ub)) and is a rather clean measure of this CKM-phase, since the hadronic uncertainties affecting x can be absorbed through the colour-suppression factor a2. Since, moreover, BR(B(s) --> pi0PHI) = O(10(-7)) should be of comparable size as BR(B(s) --> rho0K(S)), we suggest that B(s) --> pi0PHI may be a promising mode to extract gamma.