Combined fit to BaBar and Belle data on e+e- to pi+pi- psi(2S)

TL;DR

This paper performs a combined analysis of BaBar and Belle data to precisely determine the properties of Y(4360) and Y(4660) resonances in e+e- to pi+pi- psi(2S) reactions, providing insights into their nature.

Contribution

It presents the first combined fit to BaBar and Belle data, accurately extracting the masses, widths, and production rates of Y(4360) and Y(4660) resonances.

Findings

Y(4360) mass: 4355^{+9}_{-10} ext{MeV}/c^2

Y(4660) mass: 4661^{+9}_{-8} ext{MeV}/c^2

Y(4260) production in pi+pi-psi(2S) mode is at 2σ level

Abstract

A combined fit is performed to the BaBar and Belle measurements of the e+e- to pi+pi-psi(2S) cross sections for center-of-mass energy between threshold and 5.5 GeV. The resonant parameters of the Y(4360) and Y(4660) are determined. The mass is 4355^{+9}_{-10}\pm 9 MeV/c^2 and the width is 103^{+17}_{-15}\pm 11 MeV/c^2 for the Y(4360), and the mass is 4661^{+9}_{-8}\pm 6 MeV/c^2 and the width is 42^{+17}_{-12}\pm 6 MeV/c^2 for the Y(4660). The production of the Y(4260) in pi+pi-psi(2S) mode is found to be at 2\sigma level, and B(Y(4260) to pi+pi-psi(2S))\Gamma_{e+e-} is found to be less than 4.3 eV/c^2 at the 90% confidence level, or equal to 7.4^{+2.1}_{-1.7} eV/c^2 depending on it interferes with the Y(4360) constructively or destructively. These information will shed light on the understanding of the nature of the Y states observed in initial state radiation processes.