2006/01/31 by Peter Lichard, P. Lichard, Josef Juráň +1
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1103/physrevd.76.094030
published as Phys.Rev.D76:094030,2007 · 15 pages, 6 figures. Largely extended. The title changed to reflect new content
arxiv created 2007/10/05 · openalex publication_date 2007/11/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The excitation curve of e+e^\ensuremath- annihilation into four charged pions in the \ensuremathρ(770) region is calculated using three existing models with \ensuremathρ mesons and pions in intermediate states supplemented by Feynman diagrams with the a1(1260)\ensuremathπ intermediate states. A two-term phenomenological Lagrangian of the a1\ensuremathρ\ensuremathπ interaction is used. The mixing angle is determined by fitting the e+e^\ensuremath-\ensuremath→\ensuremathπ+\ensuremathπ^\ensuremath-\ensuremathπ+\ensuremathπ^\ensuremath- cross section data of the Novosibirsk CMD-2 Collaboration and also its combination with the low-energy part of the BABAR Collaboration data. It is shown that the inclusion of the a1\ensuremathπ intermediate states succeeds in obtaining a good agreement with the data on both cross section and the \ensuremathρ0\ensuremath→\ensuremathπ+\ensuremathπ^\ensuremath-\ensuremathπ+\ensuremathπ^\ensuremath- decay width. When moving to energies above 1 GeV, the \ensuremathρ(1450) and \ensuremathρ(1700) resonances are taken into account to get excellent agreement with the BABAR data over the full energy range up to 4.5 GeV.