2007/01/31 by E. Hernández, E. Hernandez, J. Nieves +1 · 5 citations
Physics and Astronomy · #Hadron #High-Energy Particle Collisions Research #Neutrino #Nuclear physics #Nucleon #Parity (physics) #Particle physics #Particle physics theoretical and experimental studies #Physics #Pion #Production (economics) #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Resonance (particle physics) #Scattering #Scattering cross-section #hep-ph
paper · pdf · doi:10.1103/physrevd.76.033005
published as Phys.Rev.D76:033005,2007 · Typos corrected; comments added
arxiv created 2007/06/19 · openalex publication_date 2007/08/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We develop a model for the weak pion production off the nucleon, which besides the delta pole mechanism [weak excitation of the \ensuremathΔ(1232) resonance and its subsequent decay into N\ensuremathπ], includes also some background terms required by chiral symmetry. We refit the C5A(q2) form factor to the flux-averaged \ensuremathν_\ensuremathμp\ensuremath→\ensuremathμ^\ensuremath-p\ensuremathπ+ ANL q2-differential cross section data, finding a substantially smaller contribution of the delta pole mechanism than traditionally assumed in the literature. Within this scheme, we calculate several differential and integrated cross sections, including pion angular distributions, induced by neutrinos and antineutrinos and driven both by charged and neutral currents. In all cases we find that the background terms produce quite significant effects, and that they lead to an overall improved description of the data, as compared to the case where only the delta pole mechanism is considered. We also show that the interference between the delta pole and the background terms produces parity-violating contributions to the pion angular differential cross section, which are intimately linked to T-odd correlations in the contraction between the leptonic and hadronic tensors. However, these latter correlations do not imply a genuine violation of time-reversal invariance because of the existence of strong final state interaction effects.