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HK: Physik der Hadronen und Kerne

HK 13: Poster Session: Theory

HK 13.9: Poster

Dienstag, 9. März 2004, 13:30–15:30, Foyer

Spectrum and decays of the kaonic hydrogen — •Udit Raha¹, Ulf-G. Meissner^1,2, and Akaki Rusetsky¹ — ¹HISKP (Th), Universität Bonn, Bonn, Germany — ²IKP (Th), FZ Jülich, Jülich, Germany

Recent accurate measurements of the strong energy shift and the lifetime of the ground state of kaonic hydrogen by DEAR collaboration at LNF-INFN[1] allow one to extract the precise values of the KN scattering lengths from the data. To this end, one needs to relate the latter quantities to the observables of the kaonic hydrogen at the accuracy that matches the experimental precision. In our recent investigations[2], the problem is considered within the non-relativistic effective Lagrangian approach, which has been previously used to describe the bound π⁺π⁻ and π⁻p systems. We obtain a general expression of the strong shift of the level energy and the decay width in terms of the KN scattering lengths, at O(α,m_d−m_u) as compared to the leading-order result. It is shown that, due to the presence of the unitarity cusp in the K⁻p elastic scattering amplitude above threshold, the isospin-breaking corrections turn out to be very large. This, however, does not affect the accuracy of the extraction of the scattering lengths from the experiment.

[1] Michael Cargnelli et al. (DEAR Collaboration), in proceedings of the 4th International Workshop on CHIRAL DYNAMICS 2003 (Theory and Experiment), Bonn, Germany, ed. U.-G. Meissner, H.-W. Hammer, and A. Wirzba, arXiv:hep-ph/0311212.

[2] U.-G. Meissner, U. Raha, and A. Rusetsky, in preparation