Hadronic phases and isospin amplitudes in D(B)→ππ and D(B)→KK̄ decays

Hadronic phases in ππ and KK̄ channels are calculated à la Regge. At the D mass one finds δππ≃π3 and δKK̄≃−π6 in good agreement with the CLEO data while at the B mass these angles are predicted to be, respectively, 11° and -7°. With the hadronic phase eiδKK̄ taken into account, a quark diagram decomposition of the isospin invariant amplitudes in D→KK̄ decays fits the data provided the exchange diagram contribution is about 1/3 of the tree level one.