Pionic deuterium
arXiv:1011.2415 · doi:10.1140/epja/i2011-11088-1
Abstract
The strong interaction shift $ε$ and broadening Î in pionic deuterium have been determined in a high statistics study of the ÏD(3p - 1s) X-ray transition using a high-resolution crystal spectrometer. The pionic deuterium shift will provide constraints for the pion-nucleon isospin scattering lengths extracted from measurements of shift and broadening in pionic hydrogen. The hadronic broadening is related to pion absorption and production at threshold. The results are ε= (-2356 {\pm} 31)meV (repulsive) and Î1s = (1171+23/-49) meV yielding for the complex ÏD scattering length a = [-(24.99 {\pm} 0.33) + i (6.22+0.12/-0.26)]x10-3/mÏ. From the imaginary part, the threshold parameter for pion production is obtained to be α = (251 +5/-11) μb. This allows, in addition, and by using results from pion absorption in 3He at threshold, the determination of the effective couplings g0 and g1 for s-wave pion absorption on isoscalar and isovector NN pairs.
19 pages, 14 figures, 8 tables accepted for publication in EPJA