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HK: Hadronen und Kerne

HK 61: Electromagnetic Probes VIII, Properties of Nucleon, Pion

HK 61.7: Vortrag

Donnerstag, 19. März 1998, 16:30–16:45, B

Generalized Polarizabilities of the Pion — •C. Unkmeir¹, A. I. L’vov², S. Scherer¹, and D. Drechsel¹ — ¹Institut f"ur Kernphysik, Johannes Gutenberg-Universit"at, J. J. Becher Weg 45, D-55099 Mainz — ²P. N. Lebedev Physical Institute, Moscow, 117924, Russia

At low energies, the structure-dependent part of the invariant amplitude for virtual Compton scattering (VCS) off pions (π e→ π eγ) can be expressed in terms of two generalized polarizabilities [1,2]. They are functions of the squared momentum transfer of the virtual photon and can be interpreted as generalizations of the well-known electromagnetic polarizabilities of real Compton scattering. We calculate the VCS amplitude in the framework of chiral perturbation theory at O(p⁴) in the momentum and quark mass expansion. The generalized polarizabilities are extracted from the general VCS amplitude.

[1] P. A. M. Guichon, G. Q. Liu, and A. W. Thomas, Nucl. Phys. A591, 606 (1995)

[2] D. Drechsel, G. Kn"ochlein, A. Metz, and S. Scherer, Phys. Rev. C 55, 424 (1997)