Hadronic weak decays of heavy mesons and nonfactorization

The parameters chi(1,2), which measure nonfactorizable soft gluon contributions to hadronic weak decays of mesons, are updated by extracting them from the data of D, B --> PP, VP decays (P: pseudoscalar meson, V: vector meson). It is found that chi(2) ranges from -0.36 to -0.60 in the decays from D --> (K) over bar pi to D+ --> phi pi(+), D --> (K) over bar*pi, while it is of order 10% with a positive sign in B --> psi K, D pi, D*pi, D rho decays. Therefore, the effective parameter a(2) is process dependent in charm decay, whereas it stays fairly stable in B decay. This is in accordance with the picture that nonfactorizable soft gluon effects become stronger when the relative momentum of the decay particles becomes smaller. As for D, B --> VV decays, the presence of nonfactorizable terms in general prevents a possible definition of effective a(1) and a(2). This is reinforced by the observation of a large longitudinal polarization fraction in B --> psi K* decay, implying nonfactorizable effects contributing differently to S-, P- and D-wave amplitudes. We found that A(1)(nf)/A(1), > 0 > A(2)(nf)/A(2), V-nf/V (ni standing for nonfactorization) for B --> psi K* decay and 0 > A(1)(nf)/A(1) > A(2)(nf)/A(2) V-nf/V for D --> (K) over bar*rho decay. A measurement of longitudinally and transversely polarized decay rates Gamma(L) and Gamma(T) in color-suppressed decay modes (B) over bar(0) --> D*(0) rho(0), D*0 omega and D+ --> phi rho(+) is urged.