Eur. Phys. J. A (2006) 27: 37-45
https://doi.org/10.1140/epja/i2006-10002-4

Nuclear Structure and Reactions

Towards a field theoretic understanding of NN → NNπ

¹ Institut für Kernphysik, Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
² Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117259, Moscow, Russia
³ Helmholtz-Institut für Strahlen- und Kernphysik (Theorie), Universität Bonn, Nußallee 14-16, D-53115, Bonn, Germany

^* e-mail: c.hanhart@fz-juelich.de

Received: 7 February 2006
Accepted: 7 February 2006
Published online: 21 February 2006

Abstract

We study the production amplitude for the reaction NN → NNπ up to next-to-leading order in chiral perturbation theory using a counting scheme that takes into account the large scale introduced by the initial momentum. In particular, we investigate a subtlety that arises once the leading loop contributions are convoluted with the NN wave functions as demanded by the non-perturbative nature of the NN interaction. We show how to properly identify the irreducible contribution of loop diagrams in such type of reaction. The net effect of the inclusion of all next-to-leading-order loops is to enhance the leading rescattering amplitude by a factor of 4/3, bringing its contribution to the cross-section for pp → dπ⁺ close to the experimental value.