Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 13: Poster Session: Theory

HK 13.1: Poster

Tuesday, March 9, 2004, 13:30–15:30, Foyer

GPD’s with a soft pion emission: chiral perturbation theory and soft pion theorem — •Nikolai Kivel — Universitat strasse 150, 44780 Bochum

Soft pion theorem was used recently in [1] to estimate contamination due to the soft pion production in DVCS. But this approach was criticized in [2] on the basis of Chiral Perturbation Theory. The authors of [2] conclude that the soft pion theorem derived in [1] is incorrect because it contrudicts to effective action of twist-2 operators in ChPT.

We recalculate the problematic matrix elements in the ChPT and find mistake in the results of [2]. Correct results are consistent with soft pion theorem for GPD’s discussed in [1].

[1]P.A.M.Guichon,L.Mosse and M.Vanderhaeghen, No-dqPion production in deeply virtual Compton ScatteringNo-dq, hep-ph/0305231

[2]J. W. Chen and M. J. Savage,“Soft pion emission in DVCS,” arXiv:nucl-th/0308033.