PROTON INDUCED K + PRODUCTION ANDTHE s s CONTENT OF THE PROTON

We investigate the exclusive proton{induced K + production near the kaon threshold. Compared are two models: a meson{exchange model, which includes ; ; K and K exchange, together with the dominant baryon resonances, and a quark{gluon model, where momentum sharing is provided via the exchange of two gluons. Based on covariant bound state wave functions for the meson and the baryons | which we treat as quark{ diquark objects | rst results for the pp ! pK + total cross section are presented for both models. Numerous calculations in diierent QCD{inspired quark models have indicated that mesons and baryons can be described qualitatively as objects, which involve dominantly q q and 3q valence quarks, respectively. Recently, however, particularly with the so called "spin crisis of the nucleon", the question on the admixture of seaquarks in hadrons has been raised 1]. In view of recent experimental activities at various hadron factories, such as COSY or CELSIUS, one promising source of information on the s s content of the proton is the exclusive K + production in pp ! NY K, with Y being a or hyperon: in the simplest picture, the production process can be viewed as the excitation of an s s pair in the proton, which is subsequently | during the scattering process | put on its mass shell. The standard approach to meson production is the meson{exchange model, where the large momentum transfer of typically 1 GeV/c is shared between the hadrons by meson exchange 2]]3] (Fig. 1a). The dominant contributions are expected from the exchange of (;) in the nonstrange and (K; K) in the strange meson sector, whereas the rescattering amplitude