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Electromagnetic corrections.

Extending the pioneering work of Rasche and Woolcock [6] the electromagnetic corrections to the pion nucleon scattering lengths have been calculated in a recent publication [42] with a relativistic two channel approach. The results for the correction to the shift measurement \( \delta _{\varepsilon } \) and the width measurement \( \delta _{\Gamma } \) are \( \delta _{\varepsilon } \)=-(2.1\( \pm \)0.5)\( \times \)10\( ^{-2} \) and \( \delta _{\Gamma } \)=-(1.3\( \pm \)0.5)\( \times \)10\( ^{-2} \), respectively. The uncertainty of 5 \( \times 10^{-3} \) together with the error in the Panofsky ratio can be considered as the final accuracy the experiment should reach.


Pionic Hydrogen Collaboration
1998