Hadronic transitions from Upsilon(4S) as a probe of four-quark admixture

TL;DR

The paper proposes that the Upsilon(4S) resonance contains a four-quark component, explaining certain hadronic transition enhancements, and suggests experimental tests and discusses related four-quark states.

Contribution

It introduces the idea that Upsilon(4S) has a four-quark admixture affecting its decay patterns, providing a new perspective on its structure.

Findings

Enhanced Upsilon(4S) -> Upsilon(1S) eta transition explained by four-quark admixture

Suggested experimental search for Upsilon(4S) -> Upsilon(1S) eta'(958)

Discussion of properties of related four-quark states

Abstract

It is argued that the observed enhancement of the hadronic transition Upsilon(4S) -> Upsilon(1S) eta relative to Upsilon(4S) -> Upsilon(1S) pi pi can be explained if the resonance Upsilon(4S) contains an admixture of a four-quark component, possibly due to the coupling to the meson channel B \bar B. A test of the discussed mechanism by searching for the transition Upsilon(4S) -> Upsilon(1S) eta'(958) is suggested. Some properties of possible four-quark states related to the suggested one by the heavy quark spin symmetry are also discussed.