Kaon Pair Production in Proton--Proton Collisions

TL;DR

This study measures kaon pair production cross sections in proton-proton collisions near threshold energies, analyzing the role of final state interactions and phi-meson decay contributions, providing insights into kaon-proton interactions.

Contribution

First detailed measurement of kaon pair production cross sections at near-threshold energies, with analysis of final state interactions and phi-meson decay effects.

Findings

Differential cross sections peak at low K-p and K+ invariant masses.

Data sensitive to K-p scattering length magnitude.

Model describes phi and non-phi contributions well across energies.

Abstract

The differential and total cross sections for kaon pair production in the pp->ppK+K- reaction have been measured at three beam energies of 2.65, 2.70, and 2.83 GeV using the ANKE magnetic spectrometer at the COSY-Juelich accelerator. These near-threshold data are separated into pairs arising from the decay of the phi-meson and the remainder. For the non-phi selection, the ratio of the differential cross sections in terms of the K-p and K+p invariant masses is strongly peaked towards low masses. This effect can be described quantitatively by using a simple ansatz for the K-p final state interaction, where it is seen that the data are sensitive to the magnitude of an effective K-p scattering length. When allowance is made for a small number of phi events where the K- rescatters from the proton, the phi region is equally well described at all three energies. A very similar phenomenon is discovered in the ratio of the cross sections as functions of the K-pp and K+pp invariant masses and the identical final state interaction model is also very successful here. The world data on the energy dependence of the non-phi total cross section is also reproduced, except possibly for the results closest to threshold.