The Search for eta(1440) --> K^0_S K^pm \pi^mp in Two-Photon Fusion at CLEO

TL;DR

This study investigates the production of mesons in two-photon collisions at CLEO, finding evidence for axial-vector mesons near 1440 MeV but not for the eta(1440), and setting upper limits on pseudoscalar meson production.

Contribution

The paper provides the first detailed analysis of two-photon production of K0_S K± π∓ final states at CLEO, distinguishing between axial-vector and pseudoscalar mesons, and challenges previous eta(1440) observations.

Findings

Detected enhancements near 1440 MeV consistent with axial-vector mesons.

Did not observe eta(1440) production, conflicting with prior L3 results.

Set upper limits on two-photon widths and branching fractions for pseudoscalar mesons.

Abstract

We analyze 13.8 \rm fb^{-1} of the integrated e^+e^- luminosity collected at 10.6 GeV center-of-mass energy with the CLEO II and CLEO II.V detectors to study exclusive two-photon production of hadrons with masses below 1.7{\rm \ GeV/c^2} decaying into the K^0_S K^\pm \pi^\mp final state. We observe two statistically significant enhancements in the \eta(1440) mass region. These enhancements have large transverse momentum which rules them out as being due to pseudoscalar resonances but is consistent with the production of axial-vector mesons. We use tagged two-photon events to study the properties of the observed enhancements and associate them with the production of f_1(1285) and f_1(1420). Our non-observation of \eta(1440) is inconsistent by more than two standard deviations with the first observation of this resonance in two-photon collisions by the L3 experiment. We present our estimates for 90% confidence level upper limits on the products of two-photon partial widths of pseudoscalar hadrons and their branching fractions into K^0_S(\pi^+\pi^-)K^\pm\pi^\mp.