Improved Measurement of Branching Fractions for pipi Transitions among Upsilon(nS)States

TL;DR

This paper presents improved measurements of branching fractions for specific Upsilon(nS) to Upsilon(1S) and Upsilon(2S) transitions involving pion pairs, using large data samples collected with the CLEO detector.

Contribution

The study provides more precise branching fraction values for five Upsilon transitions, enhancing previous measurements with larger data samples and reduced uncertainties.

Findings

Measured five Upsilon transition branching fractions with improved precision.

Reported branching fractions with statistical and systematic uncertainties.

Enhanced understanding of bottomonium decay processes.

Abstract

Using samples of (5.93 +/- 0.10) x 10^6 Upsilon(3S) decays and (9.11 +/- 0.14) x 10^6 Upsilon(2S) decays collected with the CLEO detector, we report improved measurements of the branching fractions for the following five transitions: B(Upsilon(3S)-->Upsilon(1S) pi^+ pi^-) = (4.46 +/- 0.01 +/- 0.13)%, B(Upsilon(2S)-->Upsilon(1S) pi^+ pi^-) = (18.02 +/- 0.02 +/- 0.61)%, B(Upsilon(3S)-->Upsilon(1S) pi^0 pi^0) = (2.24 +/- 0.09 +/- 0.11)%, B(Upsilon(2S)-->Upsilon(1S) pi^0 pi^0) = (8.43 +/- 0.16 +/- 0.42)% and B(Upsilon(3S)-->Upsilon(2S) pi^0 pi^0) = (1.82 +/- 0.09 +/- 0.12)%. In each case the first uncertainty reported is statistical, while the second is systematic.