Abstract
We present the analysis of K− absorption processes on He4 leading to Λπ− final states, measured with the KLOE spectrometer at the DAΦNE e+e− collider and extract, for the first time, the modulus of the non-resonant K−n →Λπ− direct production amplitude about 33 MeV below the K‾N threshold. This analysis also allows to disentangle the K− nuclear absorption at-rest from the in-flight capture, for K− momenta of about 120 MeV. The data are interpreted with the help of a phenomenological model, and the modulus of the non-resonant K−n →Λπ− amplitude for K− absorption at-rest is found to be |AK−n→Λπ−|=(0.334±0.018stat−0.058+0.034syst)fm.
Highlights
Experiments with low energy negatively charged kaon beams directed on gaseous or solid targets are unique to study the antikaon–nucleon/nuclei interactions, by performing measurements of the kaonic atoms de-excitations, or by detecting the final states following K− absorption processes
The in-flight capture process consists in the kaon propagation through the electron cloud, followed by the nuclear absorption
The measured p π, m π and cos(θ π ) spectra were fitted with calculated distributions expressed in terms of K−n→ π − transition amplitudes: the isospin I = 1 S-wave amplitude and the resonant I = 1 P-wave amplitude which is dominated by the
Summary
Experiments with low energy negatively charged kaon beams directed on gaseous or solid targets are unique to study the antikaon–nucleon/nuclei interactions, by performing measurements of the kaonic atoms de-excitations, or by detecting the final states following K− absorption processes. In the case of interactions at-rest the underlying mechanism consists in the capture of the strange meson in a highly excited atomic state and a successive cascade to low-lying states, followed by the K− nuclear capture. The in-flight capture process consists in the kaon propagation through the electron cloud, followed by the nuclear absorption. Let us consider the process: K− A → Yπ R,
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