The strong interaction shift $\epsilon$ and broadening { \Gamma} in pionic deuterium have been determined in a high statistics study of the { \pi}D(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 \epsilon = (-2356 { \pm} 31)meV (repulsive) and { \Gamma}1s = (1171+23/-49) meV yielding for the complex { \pi}D scattering length a = [-(24.99 { \pm} 0.33) + i (6.22+0.12/-0.26)]x10-3/m{ \pi}. From the imaginary part, the threshold parameter for pion production is obtained to be { \alpha} = (251 +5/-11) { \mu}b. 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.
Categories: nucl-ex