Production of Y(1S) Mesons from chib Decays in pp(bar) Collisions at sqrt(s)=1.8 TeV

TL;DR

This paper measures the fractions of Upsilon(1S) mesons originating from chi_b decays in proton-antiproton collisions at 1.8 TeV, providing insights into bottomonium production mechanisms.

Contribution

First measurement of the fraction of Upsilon(1S) mesons from chi_b decays in high-energy proton-antiproton collisions.

Findings

Approximately 27% of Upsilon(1S) come from chi_b(1P) decays.

About 10% of Upsilon(1S) originate from chi_b(2P) decays.

Nearly 51% of Upsilon(1S) are produced directly.

Abstract

We have reconstructed the radiative decays $\chi_{b}(1P) \to \Upsilon(1S) \gamma $ and $\chi_{b}(2P) \to \Upsilon(1S) \gamma $ in $p \bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV, and measured the fraction of $\Upsilon(1S)$ mesons that originate from these decays. For $\Upsilon(1S)$ mesons with $p^{\Upsilon}_{T}>8.0$ GeV/$c$, the fractions that come from $\chi_{b}(1P)$ and $\chi_{b}(2P)$ decays are $(27.1\pm6.9(stat)\pm4.4(sys))%$ and $(10.5\pm4.4(stat)\pm1.4(sys))%$, respectively. We have derived the fraction of directly produced $\Upsilon(1S)$ mesons to be $(50.9\pm8.2(stat)\pm9.0(sys))%$.