The eta_c(2980) formation in two-photon collisions at LEP energies

TL;DR

This paper reports the detection of eta_c(2980) production in two-photon collisions at LEP energies, measuring its radiative width and setting limits on certain decay channels, contributing to understanding charmonium states.

Contribution

First measurement of eta_c(2980) production via multiple decay channels in gamma-gamma interactions at LEP energies, with an estimated two-photon width and decay mode limits.

Findings

Measured mma width as 13.9 b1 2.0 (stat.) b1 1.4 (syst.) b1 2.7 (BR) keV.

Set an upper limit of 5.5 keV for the mma width of the eta_c  pi+ pi- pi+ pi- decay channel.

Detected eta_c(2980) in multiple decay modes, confirming its production in gamma-gamma interactions.

Abstract

eta_c(2980) production in gamma-gamma interactions has been detected via its decays into K0_s K+/- pi-/+, K+ K- K+ K- and K+ K- pi+ pi- in the data taken with the DELPHI detector at LEP1 and LEP2 energies. The two-photon radiative width averaged over all observed decay channels is \Gamma_{\gamma\gamma} = 13.9 +/- 2.0 (stat.) +/- 1.4 (syst.) +/- 2.7 (BR) keV. No direct decay channel eta_c -> pi+ pi- pi+ pi- has been observed. An upper limit $\Gamma_{\gamma\gamma}$ < 5.5 keV at 95% confidence level has been evaluated for this decay mode.