The production of K+K- pairs in proton-proton collisions below the phi meson threshold

TL;DR

This study measures the production of K+K- pairs in proton-proton collisions below the phi meson threshold, revealing strong K-p interactions and evidence of channel coupling, with implications for understanding meson production dynamics.

Contribution

It provides the first detailed analysis of K+K- production below the phi threshold, highlighting the importance of final state interactions and channel coupling effects.

Findings

K-p interaction is stronger than at higher energies

Clear cusp effect at the K0K0bar threshold

Evidence for coupling between K-p and K0bar n channels

Abstract

The pp -> ppK+K- reaction was measured below the phi threshold at a beam energy of 2.568 GeV using the COSY-ANKE magnetic spectrometer. By assuming that the four-body phase space is distorted only by the product of two-body final state interactions, fits to a variety of one-dimensional distributions permit the evaluation of differential and total cross sections. The shapes of the distributions in the Kp and Kpp invariant masses are reproduced only if the K-p interaction is even stronger than that found at higher energy. The cusp effect in the K+K- distribution at the K0K0bar threshold is much more clear and some evidence is also found for coupling between the K-p and K0bar n channels. However, the energy dependence of the total cross section cannot be reproduced by considering only a simple product of such pair-wise final state interactions.