Study of Y(5S) decays to B0 and B+ mesons

TL;DR

This study measures the production rates and decay channels of B mesons from Y(5S) resonance decays using Belle detector data, providing detailed insights into B meson production fractions at this energy.

Contribution

It presents the first comprehensive measurement of B meson production fractions and decay channel contributions from Y(5S) decays at KEKB.

Findings

Measured B^+ and B^0 production rates per bb̄ event.

Determined fractions of bb̄ events transitioning to various B meson pair channels.

Quantified multi-body decay channel contributions at Y(5S).

Abstract

Decays of the Y(5S) resonance to channels with B^+ and B^0 mesons are studied using a 23.6 fb^-1 data sample collected on the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. The fully reconstructed B^+ -> J/\psi K^+, B^0 -> J/\psi K^{*0}, B^+ -> bar_D^0 pi^+ and B^0 -> D^- pi^+ decays are used to obtain the B^+ and B^0 production rates per bb_bar event, f(B^+) = (67.5 \pm 3.6 \pm 4.8)% and f(B^0)=(70.4^{+5.2}_{-5.1} \pm 6.2)%$. Assuming equal rates to B^+ and B^0 mesons in all channels produced at the Y(5S) energy, we measure the fractions for bb_bar event transitions to the two-body and multi-body channels with B^{+/0} meson pairs, f(B\bar{B}) = (5.1 \pm 0.9 \pm 0.4)%, f(B\bar{B}^*+B^*\bar{B}) = (12.6^{+1.2}_{-1.1} \pm 1.0)%, f(B^*\bar{B}^*) = (34.5^{+1.9}_{-1.8} \pm 2.7)%, f(B^{(*)}\bar{B}^{(*)}\pi(\pi)) = (16.4^{+1.6}_{-1.5} \pm 1.2)%, f(B\bar{B} \pi) = (0.0 \pm 1.1 \pm 0.2)%, f(B\bar{B}^*\pi+B^*\bar{B}\pi) = (6.8^{+2.1}_{-2.0} \pm 0.7)%, and f(B^*\bar{B}^*\pi) = (1.0^{+1.3}_{-1.2} \pm 0.3)%.