Soft Nonfactorizable Contribution to \bar{B}^0 \to D^0\pi^0

Abstract

For the color-suppressed ${\bar{B}}^0⟶D^0{\pi }^0$ decay, nonfactorizable contributions are expected to be leading and naive factorization description breaks down. We estimate $1/m_b$ power-suppressed nonfactorizable effect in ${\bar{B}}^0⟶D^0{\pi }^0$, which is due to soft exchange between the emitted heavy-light quark pair and $B\pi$ system, in the framework of QCD light-cone sum rules (LCSR). The resulting correction to the decay amplitude is found to be numerically comparable with the corresponding factorizable piece, estimated at about $(50-110)$ of the latter. The relevant parameter $a_2$ receives a positive number contribution, due to the factorizable correction and the power-suppressed soft effect. Our findings would be crucial to phenomenological understanding of the ${\bar{B}}^0⟶D^0{\pi }^0$ decay.

Comments: 15 pages, revtex, accepted for publication in EPJC