$K\bar{K}$ PRODUCTION AT COSY

Abstract

Near threshold [Formula: see text] production has been studied in several hadronic reactions at COSY. Data on pp→ppK+K- and pd→3HeK+K- are available at several excess energies. ϕ mesons are clearly observed whereas the contribution from the scalar resonances a0/f0(980) is unclear. Data on [Formula: see text] were measured at two excess energies and for the lower energy the total cross section as well as differential distributions have been extracted. The main contribution to this reaction is identified as the [Formula: see text] channel. Furthermore, the differential distributions may give information on the [Formula: see text] FSI and scattering length. The data at the higher energy are still under analysis, and a preliminary value for the total cross section is given. [Formula: see text] production in pn reactions is also investigated in a recently performed measurement.