Pionic deuterium
نویسندگان
چکیده
The strong-interaction shift πD 1s and broadening Γ πD 1s in pionic deuterium have been determined in a high statistics study of the πD(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 πD 1s = (−2356 ± 31)meV (repulsive) and Γ 1s = (1171 +23 −49)meV yielding for the complex πD scattering length aπD = [−(24.99±0.33)+i(6.22 −0.26)]× 10−3 m−1 π . From the imaginary part, the threshold parameter for pion production is obtained to be α = (251 −11)μb. This allows, in addition, and by using results from pion absorption in He at threshold, the determination of the effective couplings g0 and g1 for s-wave pion absorption on isoscalar and isovector NN pairs.
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