Measurement of Branching Fractions for $B\to {\chi }_{c1(2)}K(K^{\ast })$ at Belle

Abstract

We have measured the branching fractions for the exclusive decay modes $B\to {\chi }_{c1(2)}K(K^{\ast })$ using a $140{\mathrm{fb}}^{-1}$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The measured branching fractions for $B^{+}\to {\chi }_{c1}{K}^{+}$, $B^0\to {\chi }_{c1}{K}^0$, $B^0\to {\chi }_{c1}{K}^{\ast 0}$ and $B^{+}\to {\chi }_{c1}{K}^{\ast +}$ decay modes are $(4.5\pm 0.2\pm 0.5)\times 10^{-4}$, $(3.5\pm 0.3\pm 0.5)\times 10^{-4}$, $(3.1\pm 0.3\pm 0.7)\times 10^{-4}$ and $(4.1\pm 0.6\pm 0.9)\times 10^{-4}$, respectively, where the first error is statistical and the second error is systematic. We do not observe statistically significant signals for the $B\to {\chi }_{c2}K(K^{\ast })$ decay modes and set upper limits at the 90% confidence level. We also study the helicity distribution for $B\to {\chi }_{c1}{K}^{\ast }$ decay mode and show that the longitudinal polarization component is dominant. {{\it Keywords:} {$B$-meson, Charmonium, Branching Fractions, Polarization}} {{\it PACS:} 13.25.Hw, 11.30.Er}

21 pages, 5 figures, 3 tables. Submitted to PLB