1. Pionic hydrogen and deuterium
- Author
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Gotta D., Amaro F.D., Anagnostopoulos D.F., Bühler P., Covita D.S., Fuhrmann H., Gorke H., Gruber A., Hennebach M., Hirtl A., Ishiwatari T., Indelicato P., Jensen T.S., Le Bigot E.-O., Liu Y.-W., Manil B., Markushin V.E., Marton J., Nekipelov M., Pomerantsev V.N., Popov V.P., el Hassani A. J. Rusi, dos Santos J. M. F., Schlesser S., Schmid Ph., Simons L.M., Strauch Th., Theisen M., Trassinelli M., Veloso J. F. C. A., and Zmeskal J.
- Subjects
Physics ,QC1-999 - Abstract
The strong-interaction effects both in pionic hydrogen and deuterium atoms have been re-determined with improved precision. The hadronic shift and width in pionic hydrogen together with the hadronic shift in pionic deuterium constitute a one-fold constraint for the two independent pion-nucleon scattering lengths. Furthermore, the hadronic width in pionic deuterium measures the transition strength of s-wave pions on an isoscalar nucleon-nucleon pair which is an independent quantity not related to the pion-nucleon scattering lengths. The experiment was performed at the Paul Scherrer Institute by stopping a high-intensity low-energy pion beam in gaseous targets using the cyclotron trap. The X-rays emitted by the πH and πD atoms were analysed with a high resolution Bragg spectrometer equipped with spherically bent crystals. The pion-nucleon scattering lengths and other physical quantities extracted from the atom data are in good agreement with the results obtained from pionnucleon and nucleon-nucleon scattering experiments and confirm that a consistent picture is achieved for the low-energy pion-nucleon sector with respect to the expectations of chiral perturbation theory.
- Published
- 2022
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