2010/11/26 by Brian D. Serot, Xilin Zhang, Serot, Brian D. +1 · 1 citation
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #Particle physics theoretical and experimental studies #hep-ph #nucl-th
paper · pdf · doi:10.48550/arxiv.1011.5913
46 pages, 17 figures, 2 tables, LaTeX2e and REVTeX
arxiv created 2010/11/26 · arxiv updated 2010/11/30
Neutrino-induced pion and photon production from nucleons and nuclei are important for the interpretation of neutrino-oscillation experiments, and these processes are potential backgrounds in the MiniBooNE experiment [A. A. Aquilar-Arevalo et al. (MiniBooNE Collaboration), Phys. Rev. Lett. \bf 100, 032301 (2008)]. Pion and photon production are investigated at intermediate energies, where the Δ resonance becomes important. The Lorentz-covariant effective field theory contains nucleons, pions, Deltas, isoscalar scalar (σ) and vector (ω) fields, and isovector vector (ρ) fields. The lagrangian exhibits a nonlinear realization of (approximate) SU(2)L ⊗ SU(2)R chiral symmetry and incorporates vector meson dominance. Power counting for vertices and Feynman diagrams involving the Δ is explained. Because of the built-in symmetries, the vector currents are automatically conserved, and the axial-vector currents satisfy PCAC. The irrelevance of so-called off-shell Δ couplings and the structure of the dressed Δ propagator, which has a pole only in the spin-3/2 channel, are discussed. To calibrate the axial-vector transition current (N ↔ Δ), pion production from the nucleon is used as a benchmark and compared to bubble-chamber data from Argonne and Brookhaven National Laboratories. At low energies, the convergence of our power-counting scheme is investigated, and next-to-leading-order tree-level corrections are found to be very small.