First Results on K+ Production in pp and pD Interactions from ANKE and Planned Experiments on the Light Scalar Resonances a0/f0(980) at COSY

Abstract

ANKE is a magnetic spectrometer and detection system at an internal target position of COSY-Juelich optimized for charged kaon detection. Recent results from ANKE on kaon production in pp and pD interactions are reported. From the pp data first absolutely normalized angular and invariant-mass spectra for the reaction pp -> dK+ K0-bar have been obtained. A partial-wave decomposition reveals a strong contribution of S-wave KK-bar pairs with low relative energy, suggesting dominance of resonant kaon production via the a0+(980). This indicates that systematic studies of the light scalar resonances a0/f0(980) are possible at COSY. Final goal of these measurements -- requiring a neutral-particle detector which is not yet available -- is to obtain information about the charge-symmetry breaking a0-f0 mixing. From the analysis of the pD data it is concluded that the K+ production cross section on the neutron is significantly larger as compared to the proton. A cross-section ratio of sigma(n)/sigma(p) ~ 4 is deduced.