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

TL;DR

This study measures the branching fractions of specific B-meson decays to charmonium states and kaons, providing new experimental data and insights into decay dynamics and polarization, using a large data sample from the Belle detector.

Contribution

First precise measurements of branching fractions for B to χc1(2) K(K*) decays and analysis of polarization, with new upper limits for χc2 modes.

Findings

Measured branching fractions for B→χc1K and B→χc1K* decays.

No significant signals for B→χc2K(K*) decays, upper limits set.

Dominant longitudinal polarization observed in B→χc1K* decays.

Abstract

We have measured the branching fractions for the exclusive decay modes $B\to {\chi}_{c1(2)} K(K^*)$ using a $140~{\rm fb}^{-1}$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The measured branching fractions for $B^+\to {\chi}_{c1}K^+$, $B^0\to {\chi}_{c1}K^0$, $B^0\to {\chi}_{c1}K^{*0}$ and $B^+\to {\chi}_{c1}K^{*+}$ decay modes are $(4.5\pm 0.2\pm0.5)\times 10^{-4}$, $(3.5\pm 0.3\pm0.5)\times 10^{-4}$, $(3.1\pm 0.3\pm0.7)\times 10^{-4}$ and $(4.1\pm 0.6\pm0.9)\times 10^{-4}$, respectively, where the first error is statistical and the second error is systematic. We do not observe statistically significant signals for the $B\to {\chi}_{c2}K(K^*)$ decay modes and set upper limits at the 90% confidence level. We also study the helicity distribution for $B\to {\chi}_{c1} K^*$ 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}