Importance of Higher Twist Effects to Understand Charmed Color-Suppressed $B$ Decays

Abstract

Working within the framework of the QCD light cone sum rules (LCSR), we compute and discuss the nonfactorizable higher twist effect in ${\bar{B}}^0\to D^{\ast 0}{\pi }^0$ to make an all-around examination of its role in the charmed color-suppressed B decays. Analogously to the case of ${\bar{B}}^0\to D^0{\pi }^0$, such effect turns out to be of the same strong phase as the factorizable amplitude, and modifies constructively the magnitude by order $(40-90)$ so that the effective coefficient $a_2^f=C_1+C_2/3$ receives a positive correction comparable numerically with it. Nonleading as the soft effect in question is, our findings for it, along with the previous LCSR analyses of ${\bar{B}}^0\to D^0{\pi }^0$, are suggestive of the dominance of soft exchanges in these charmed color suppressed B decays. Also, the emphases are put on importance of understanding intensively various related higher twist and transverse momentum effects to interpret the data on $B\to D^{0(\ast 0)}({\pi }^0,\eta ,{\eta }^{\prime }),J/\psi K^{(\ast )}$.

Comments: Latex, 11 pages, 1 figure