Observation of π⁻K⁺ and π⁺K⁻ atoms

Abstract

Abstract. Experiment DIRAC at CERN PS detects 349 ± 62 pairs from π − K + and π + K − atoms and makes observation of exotic atoms consist of pion and kaon. It allows to measure a difference of S-wave pion-kaon scattering length with isospin 1/2 and 3/2: |a 1/2 0 − a 3/2 0 |. Values of pion-kaon scattering lengths are predicted in a frame of ChPT and LQCD. Therefore investigation of π − K + and π + K − atoms gives possibility to check these predictions for simplest hadronhadron system with s-quark.