Observation of Color-suppressed $\bar{B}^0 \to D^{0}π^0$, $D^{*0}π^0$, $D^0η$, and $D^0ω$ Decays

Abstract

We report the first observation of color-suppressed $\bar{B}{}^0 \to D^0 π^0$, $D^{*0} π^0$, $D^{0} η$, and $D^{0}ω$ decays and evidence for $\bar{B}{}^0 \to D^{*0} η$ and $D^{*0}ω$. The branching fractions are found to be ${\cal B} (\bar{B}{}^0 \to D^0 π^0) = (3.1 \pm 0.4 \pm 0.5) \times 10^{-4}$, ${\cal B} (\bar{B}{}^0 \to D^{*0} π^0) = (2.7 ^{+0.8}_{-0.7} ^{+0.5}_{-0.6})\times 10^{-4}$, ${\cal B} (\bar{B}{}^0 \to D^0 η) = (1.4 ^{+0.5}_{-0.4}\pm 0.3) \times 10^{-4}$, ${\cal B} (\bar{B}{}^0 \to D^0 ω) = (1.8 \pm 0.5 ^{+0.4}_{-0.3}) \times 10^{-4}$, and we set 90% confidence level upper limits of ${\cal B} (\bar{B}{}^0 \to D^{*0} η) < 4.6\times 10^{-4}$ and ${\cal B} (\bar{B}{}^0 \to D^{*0} ω) < 7.9 \times 10^{-4}$. The analysis is based on a data sample of 21.3 fb$^{-1}$ collected at the $Υ(4S)$ resonance by the Belle detector at the KEKB $e^{+} e^{-}$ collider.