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Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold

C. Hanhart·N. Kaiser
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Abstract

Based on a counting scheme that explicitly takes into account the large momentum sqrt(M m_pi) characteristic for pion production in nucleon-nucleon collisions we calculate all diagrams for the reaction NN --> NN pi at threshold up to next-to-leading order. At this order there are no free parameters and the size of the next-to-leading order contributions is in line with the expectation from power counting. The sum of loop corrections at that order vanishes for the process pp --> pp pi^0 at threshold. The total contribution at next-to-leading order from loop diagrams that include the delta degree of freedom vanishes at threshold in both reaction channels pp --> pp pi^0, pn pi^+.

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C. Hanhart, N. Kaiser. 2002-08-26. Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold. https://doi.org/10.1103/physrevc.66.054005

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