Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions

Details Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions

2012-01-20

arxiv.org/abs/1201.4331v1

Physics

Nuclear Physics

Nuclear Theory

28 pages, 7 figures, 2 tables

Scientific paper

A complete calculation of the pion-nucleon loops that contribute to the transition operator for $NN\to NN\pi$ up-to-and-including next-to-next-to-leading order (N$^2$LO) in chiral effective field theory near threshold is presented. The evaluation is based on the so-called momentum counting scheme, which takes into account the relatively large momentum of the initial nucleons inherent in pion-production reactions. We show that the significant cancellations between the loops found at next-to-leading order (NLO) in the earlier studies are also operative at N$^2$LO. In particular, the $1/m_N$ corrections (with $m_N$ being the nucleon mass) to loop diagrams cancel at N$^2$LO, as do the contributions of the pion loops involving the low-energy constants $c_i$, i=1...4. In contrast to the NLO calculation however, the cancellation of loops at N$^2$LO is incomplete, yielding a non-vanishing contribution to the transition amplitude. Together with the one-pion exchange tree-level operators, the loop contributions provide the long-range part of the production operator. Finally, we discuss the phenomenological implications of these findings. In particular, we find that the amplitudes generated by the N$^2$LO pion loops yield contributions comparable in size with the most important phenomenological heavy-meson exchange amplitudes.

Affiliated with

Also associated with

No associations

Rating

Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-321153