We present evidence for the first observation of electromagnetically bound π± K∓-pairs (πK-atoms) with the DIRAC experiment at the CERN-PS. The πK-atoms are produced by the 24 GeV / c proton beam in a thin Pt-target and the π± and K∓-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 ± 54 πK-atoms. The mean life of πK-atoms is related to the s-wave πK-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level. © 2009 Elsevier B.V. All rights reserved.
Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Benelli, A., … Zrelov, P. (2009). Evidence for πK-atoms with DIRAC. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 674(1), 11–16. https://doi.org/10.1016/j.physletb.2009.03.001