Study of $\chi_{c1}$ and $\chi_{c2}$ Meson Production in B Meson Decays

TL;DR

This study measures B meson decay rates to chi_c1 and chi_c2 states, finding significant chi_c1 production but no significant chi_c2 signal, providing constraints on charmonium production models.

Contribution

First precise measurement of B decays to chi_c1 and chi_c2, including direct production rates and upper limits, using a large B meson sample with detailed decay analysis.

Findings

Measured inclusive chi_c1 production branching fraction as 4.14e-3.

Set upper limits for chi_c2 production branching fractions.

Observed strong chi_c1 signals but no significant chi_c2 signals.

Abstract

Using a sample of 9.7 million B meson pairs collected with the CLEO detector, we study B decays to the chi_c1 and chi_c2 charmonia states, which are reconstructed via their radiative decays to J/psi. We first measure the branching fraction for inclusive chi_c1 production in B decays to be Br(B->chi_c1 X)=(4.14+-0.31+-0.40)*10^-3, where the first uncertainty is statistical and the second one is systematic. We derive the branching fractions for direct chi_c1 and chi_c2 production in B decays by subtracting the known contribution of the decay chain B->psi(2S)X with psi(2S)->chi_c1,2 gamma. We obtain Br[B->chi_c1(direct) X]=(3.83+-0.31+-0.40)*10^-3. No statistically significant signal for chi_c2 production is observed in either case. Using the Feldman-Cousins approach, we determine the 95% confidence intervals to be [0.2, 2.0]*10^-3 for Br(B->chi_c2 X), [0.0,1.7]*10^-3 for Br[B->chi_c2(direct) X], and [0.00,0.44] for the ratio Br[B->chi_c2(direct) X]/Br[B->chi_c1(direct) X]. We also measure the branching ratio Br[B->chi_c2(direct) X_s]/Br[B->chi_c1(direct) X_s] for different X_s configurations by reconstructing B decays into exclusive final states with J/psi, a photon, a kaon, and up to four pions. For all the X_s configurations we observe a strong chi_c1 signal yet no statistically significant chi_c2 signal. We discuss how our results compare with theoretical predictions in different models of charmonium production.