1999/06/03 by Thomas Mehen, Mehen, Thomas, Iain W. Stewart +1
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-th
paper · pdf · doi:10.48550/arxiv.nucl-th/9906010
23 pages, 7 figs, Talk Presented at the Workshop on Nuclear Physics with Effective Field Theory, INT Feb. 25-26, 1999
arxiv created 1999/06/03 · openalex publication_date 1999/06/03 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Low energy phenomena involving two nucleons can be successfully described using effective field theory. Because of the relatively large expansion parameter, it is only at next-to-next-to-leading order (NNLO) where one can expect to see agreement with experiment at the few percent level. The first part of this talk will focus on radiation pion effects, which first appear at NNLO. The power counting for radiation pions is simple for center of mass momentum p~√(M mpi)=Qr, the threshold for pion production. We explain how graphs calculated with the Qr power counting scale for p~mπ. The Qr3 radiation pion contributions to nucleon-nucleon scattering are suppressed by inverse powers of the S-wave scattering lengths. However, we point out that order Qr4 radiation contributions might give a NNLO contribution for p~mpi. In the second part of the talk, results for the potential pion and contact interaction part of the NNLO 1S0 phase shift are presented. We emphasize the importance of eliminating spurious poles in the expression for the amplitude at each order in the perturbative expansion. Doing this leaves a total of three free parameters at NNLO. We obtain a good fit to the 1S0 phase shift.