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

TL;DR

This study searches for invisible decay modes of the Upsilon(1S) meson by analyzing a large dataset of Upsilon(3S) decays, aiming to detect potential new physics beyond the Standard Model.

Contribution

It provides the first upper limit on the invisible decay branching fraction of Upsilon(1S) using a novel recoil technique with a large data sample.

Findings

Upper limit on BR(Upsilon(1S) -> invisible) < 3.0 x 10^{-4} at 90% CL

No evidence found for invisible decays of Upsilon(1S)

Sets constraints on new physics models involving invisible particles

Abstract

We search for invisible decays of the Upsilon(1S) meson using a sample of 91.4 x 10^{6} Upsilon(3S) mesons collected at the BaBar/PEP-II B-factory. We select events containing the decay Upsilon(3S) -> pi+ pi- Upsilon(1S) and search for evidence of an undetectable Upsilon(1S) decay recoiling against the dipion system. We set an upper limit on the branching fraction BR(Upsilon(1S) -> invisible) < 3.0 x 10^{-4} at the 90% confidence level.