Search for Invisible Decays of the Upsilon(1S) Resonance

TL;DR

This paper reports a search for invisible decay modes of the Upsilon(1S) resonance, setting an upper limit on the branching fraction using data from the CLEO III detector, which constrains new physics models involving invisible particles.

Contribution

First measurement setting an upper limit on the invisible decay branching fraction of Upsilon(1S) using data from Upsilon(2S) decays with the CLEO detector.

Findings

Upper limit of 0.39% on the branching fraction

Used 1.2 fb^{-1} of data at Upsilon(2S) resonance

No evidence found for invisible decays

Abstract

We present a measurement of the branching fraction of invisible Upsilon(1S) decays, using 1.2 fb^{-1} of data collected at the Upsilon(2S) resonance with the CLEO III detector at CESR. After subtracting expected backgrounds from events that pass selection criteria for invisible Upsilon(1S) decay in Upsilon(2S) -> pi+ pi- Upsilon(1S), we deduce a 90% C.L. upper limit of B[Upsilon(1S) -> invisible] < 0.39%.