Search for gammagamma -> eta_b in e+e- collisions at LEP2

TL;DR

This paper reports a search for the eta_b meson in two-photon interactions at LEP2, setting upper limits on its production rate and branching ratios based on observed events and background estimates.

Contribution

First search for eta_b meson in two-photon interactions at LEP2, establishing upper limits on production and decay branching ratios.

Findings

Observed one candidate event in six-charged-particle final state.

No candidate events in four-charged-particle final state.

Set upper limits on eta_b production and decay branching ratios.

Abstract

A search for the pseudoscalar meson eta_b is performed in two-photon interactions at LEP~2 with an integrated luminosity of 699 pb^-1 collected at e+e- centre-of-mass energies from 181 GeV to 209 GeV. One candidate event is found in the six-charged-particle final state and none in the four-charged-particle final state, in agreement with the total expected background of about one event. Upper limits of Gamma_gammagamma(eta_b) * BR(eta_b -> 4 charged particles) < 48 eV Gamma_gammagamma(eta_b) * BR(eta_b -> 6 charged particles) < 132 eV are obtained at 95% confidence level, which correspond to 95% confidence level upper limits of 9.0% and 25% on these branching ratios.