1999/06/30 by Sean Fleming, Thomas Mehen, Iain W. Stewart · 1 citation
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevc.61.044005
published as Phys.Rev. C61 (2000) 044005 · 17 pages, journal version
openalex publication_date 2000/03/15 · arxiv created 2000/04/27 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The 3S1\ensuremath-3D1 mixing angle for nucleon-nucleon scattering \ensuremathε1 is calculated to next-to-next-to-leading order in an effective field theory with perturbative pions. Without pions, the low energy theory fits the observed \ensuremathε1 well for momenta less than \ensuremath∼50 MeV. Including pions perturbatively significantly improves the agreement with data for momenta up to \ensuremath∼150 MeV with one less parameter. Furthermore, for these momenta the accuracy of our calculation is similar to an effective field theory calculation in which the pion is treated nonperturbatively. This gives phenomenological support for a perturbative treatment of pions in low energy two-nucleon processes. We explain why it is necessary to perform spin and isospin traces in d dimensions when regulating divergences with dimensional regularization in higher partial wave amplitudes.