Determining the upper limit of Gamma_{ee} for the Y(4260)

TL;DR

This paper estimates the maximum possible electron width of the Y(4260) resonance using experimental R value data, indicating a potentially large decay width for its decay into pi+pi- J/psi.

Contribution

It provides the first upper limit on Gamma_{ee} for Y(4260) based on BES data, combining it with BABAR results to infer decay properties.

Findings

Upper limit of Gamma_{ee} is 580 eV at 90% C.L.

Y(4260) likely has a large decay width to pi+pi- J/psi.

Results suggest Y(4260) has unconventional decay characteristics.

Abstract

By fitting the R values between 3.7 and 5.0 GeV measured by the BES collaboration, the upper limit of the electron width of the newly discovered resonance Y(4260) is determined to be 580 eV at 90% C.L. Together with the BABAR measurement on the product of Gamma_{ee} and BR(Y(4260) --> pi+pi- J/psi), this implies a large decay width of Y(4260) --> pi+pi- J/psi final states.