Combining Information from $B \to \pi \pi $ and $B \to \pi \rho, \pi \omega $ Decays

Abstract

We consider the $B \to \pi \pi $ and $B \to \pi \rho, \pi \omega $ decays alongside each other, taking into account the contributions from all individual penguin amplitudes generated by the internal $t$, $c$, and $u$ quarks. We argue that three ratios of penguin amplitudes, each for a different internal quark, formed by dividing the individual penguin amplitude in $B \to \pi \pi$ by the corresponding amplitude in $B \to \pi \rho, \pi \omega $, should be equal. We study the implications of the assumed existence of this connection between $B\to \pi \pi$ and $B \to \pi \rho, \pi \omega $. First, accepting that in the $B \to \pi \pi$ decays the ratio $C/T$ of the colour-suppressed factorization amplitude $C$ to the tree factorization amplitude $T$ is negligible, we determine the ratio of individual penguin amplitudes. Then, from the $B \to \pi \rho, \pi \omega$ data, we extract the effective (i.e. possibly containing some penguin terms) tree and the effective colour-suppressed amplitudes relevant for these processes, and the corresponding solutions for the factorization amplitudes. Finally, we argue that the $C/T$ ratio in $B \to \pi \pi $ should be identical to its counterpart in $B \to \pi \rho, \pi \omega$ (relevant for pion emission from the decaying $b$ quark). This constraint permits the determination of $C/T$ and of other amplitude ratios directly from the data. Although the $|C/T|$ ratio extracted from the available data still carries a substantial error, it is consistent with the expected value of 0.25 - 0.5.