Testing QCD factorization with phase determinations inB→Kπ,Kρ, andK*πdecays

Abstract

The success of QCD factorization(QCDF) in predicting branching ratios for charmless $B$ decays to light pseudoscalar and vector mesons and the small CP asymmetries measured at $BABAR$, Belle and LHCb show that the phase in these decays, as predicted by QCDF, are not large. For a precise test of QCDF one needs to extract from the measured decay rates, the phase of the decay amplitude which appears in the interference terms between the tree and penguin contribution. Since the tree amplitude is known at the leading order in $\Lambda_{\rm QCD}/m_{b}$ and is consistent with the measured tree-dominated decay rates, the QCDF value for the tree amplitude can be used with the measured decay rates to obtain the phases in $B\to K\pi$,$K\rho$, and $ K^{*}\pi$ decay rates. This is similar to the extraction of the final-state interaction phases in the interference term between $p\bar{p}\to J/\Psi\to e^{+}e^{-}$ and $p\bar{p}\to e^{+}e^{-} $ and in $J/\Psi\to 0^{-}0^{-}$ done previously. In this paper, we present a determination of the phase between the $I=3/2$ tree and $I=1/2$ penguin amplitudes in $B\to K\pi$,$K\rho$ , and $ K^{*}\pi$ decays using the measured decay rates and the QCDF $I=3/2$ tree amplitude obtained from the $I=2$ $B^{+}\to \pi^{+}\pi^{0},\rho^{0}\pi^{+}, \rho^{+}\pi^{0 tree-dominated decays and compare the result with the phase given by QCDF. It is remarkable that the phase extracted from experiments differs only slightly from the QCDF values. This shows that there is no large final-state interaction strong phase in $B\to K\pi$,$K\rho$, and $ K^{*}\pi$ decays.