Branching fractions for Y(3S) -> pi^0 h_b and psi(2S) -> pi^0 h_c

TL;DR

This study measures the branching fractions of specific bottomonium and charmonium transitions involving pi^0 emission, providing upper limits and precise measurements using data from CLEO detectors.

Contribution

It presents the first upper limit for Y(3S) -> pi^0 h_b and a precise measurement for psi(2S) -> pi^0 h_c branching fractions, improving understanding of quarkonium transitions.

Findings

Upper limit for Y(3S) -> pi^0 h_b: < 1.2×10^{-3} at 90% CL

Measured B(psi(2S) -> pi^0 h_c): (9.0±1.5±1.3)×10^{-4}

Enhanced signal sensitivity by excluding asymmetric pi^0 candidates

Abstract

Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -> pi^0 h_b) < 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -> pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -> gamma gamma candidates.