Eur. Phys. J. A (2014) 50: 190
https://doi.org/10.1140/epja/i2014-14190-x

Regular Article - Experimental Physics

Hadronic shift in pionic hydrogen

¹ Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
² Department of Materials Science and Engineering, University of Ioannina, GR-45110, Ioannina, Greece
³ Laboratory for Particle Physics, Paul Scherrer Institut, CH-5232, Villigen, Switzerland
⁴ Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, A-1090, Vienna, Austria
⁵ Laboratoire Kastler Brossel, Sorbonne Universités, UPMC Univ. Paris 06, Case 74; 4, place Jussieu, 75005, Paris, France
⁶ Laboratoire Kastler Brossel, CNRS, 75005, Paris, France
⁷ Laboratoire Kastler Brossel, Département de Physique de l’École Normale Supérieure, 24 Rue Lhomond, 75005, Paris, France
⁸ Faculté des Sciences et Techniques, Université Abdelmalek Essaâdi, Tanger, Morocco
⁹ Institut des NanoSciences de Paris, Sorbonne Universités, UPMC Univ. Paris 06, Case 840; 4, place Jussieu, Paris, France
¹⁰ Institut des NanoSciences de Paris, CNRS, F-75005, Paris, France

^* e-mail: d.gotta@fz-juelich.de

Received: 17 June 2014
Revised: 31 October 2014
Accepted: 16 December 2014
Published online: 29 December 2014

Abstract

The hadronic shift in pionic hydrogen has been redetermined to be ε _1s = 7.086 ± 0.007(stat) ± 0.006(sys) eV by X-ray spectroscopy of ground-state transitions applying various energy calibration schemes. The experiment was performed at the high-intensity low-energy pion beam of the Paul Scherrer Institut by using the cyclotron trap and an ultimate-resolution Bragg spectrometer with bent crystals.