Pionic Deuterium

¹ Institut für Kernphysik, Forschungszentrum Jülich, D–52425 Jülich, Germany
² Dept. of Physics, Coimbra University, P-3000 Coimbra, Portugal
³ Dept. of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina, Greece
⁴ Stefan Meyer Institut for Subatomic Physics, Austrian Academy of Sciences, A-1090 Vienna, Austria
⁵ Zentralabteilung für Elektronik, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
⁶ Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS; Case 74, 4 place Jussieu, F-75005 Paris, France
⁷ Laboratory for Particle Physics, Paul Scherrer Institut, CH–5232 Villigen, Switzerland
⁸ Dept. of Physics, Aveiro University, P-3810 Aveiro, Portugal

^a present address: Dept. of Physics, Aveiro University, P-3810 Aveiro, Portugal
^b corresponding author: d.gotta@fz-juelich.de
^c present address: Universitätsklinik für Nuklearmedizin, Medizinische Universität Wien, 1090 Vienna, Austria
^d present address: Inst. des NanoSciences de Paris, CNRS UMR7588 and UMPC-Paris 6, F-75015 Paris, France

Abstract

The strong interaction shift ε_1s^πD and broadening Γ_1s^πD in pionic deuterium have been remeasured with high statistics by means of the πD(3p − 1s) X-ray transition using the cyclotron trap and a high-resolution crystal πD πD spectrometer. Preliminary results are ε_1s^πD = (−2325 ± 31) meV (repulsive) and Γ_1s^πD(1171⁺²³_-49) meV which yields for the πD scattering length a_πD = [−(24.8 ± 0.3) + i (6.3_-0.3^+0.1)] · 10⁻³ m_π⁻¹. From the imaginary part the threshold parameter for pion production is determined to be α = (252₋₁₁⁺¹⁵) µb.