Light resonances in Ks K pi and eta pi pi final states in gamma gamma collisions at LEP

TL;DR

This study reports the first observation of the eta(1440) meson in gamma gamma collisions at LEP, measuring its two-photon width and confirming the production of f1(1420) and f1(1285) mesons.

Contribution

It provides the first measurement of eta(1440) in gamma gamma collisions and details the production of specific axial vector mesons at LEP.

Findings

Observation of eta(1440) in gamma gamma collisions.

Measurement of eta(1440) two-photon width: 212 +/- 50(stat) +/- 23(sys) eV.

Evidence for f1(1420) and f1(1285) mesons.

Abstract

The e+e- -> e+e- Ks K+- pi-+ e+e- -> e+e- eta pi+ pi- and final states are studied with the L3 detector at LEP using data collected at centre-of-mass energies from 183 GeV up to 202 GeV. The mass spectrum of the Ks K+- pi-+ final state shows an enhancement around 1470MeV, which is identified with the pseudoscalar meson eta(1440). This state is observed in gamma gamma collisions for the first time and its two-photon width is measured to be Gamma_gamma gamma(eta(1440))x BR(eta(1440)->KK pi)= 212 +/- 50(stat) +/- 23(sys)eV. Clear evidence is also obtained for the formation of the axial vector mesons f1(1420) and f1(1285). In the eta pi+ pi- channel the f1(1285) is observed, and upper limits for the formation of eta(1440) and eta(1295) are obtained.