2006/11/13 by Peter Lichard, P. Lichard, Lichard, Peter +2 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0611163
arxiv created 2006/11/13 · openalex publication_date 2006/11/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In order to reveal possible mass shifts of the vector mesons in a dense strongly interacting medium presumably created in high energy heavy ion collisions it is necessary to know their free masses reliably. The rho(770) mass quoted in the last two editions of the Review of Particle Physics is significantly larger than the values quoted in previous editions. The new value is mostly influenced by the results of recent experiments CMD-2 and SND at the VEPP-2M e+e- collider at Novosibirsk. We show that the values of the mass and width of the rho(770) meson measured in the e+e- -> pi+pi- annihilation depend crucially on the parametrization used for the pion form factor. We propose a parametrization of the rho(770) contribution to the pion form factor based on the running mass calculated from a single-subtracted dispersion relation and compare it with the parametrization based on the formula of Gounaris and Sakurai used recently by the CMD-2 collaboration. We show that our parametrization gives equally good or better fits when applied to the data of the CMD-2, SND, and KLOE collaborations, but yields much smaller values of the rho(770) mass, consistent with the photoproduction and hadronic reactions results. Our fit to the KLOE data becomes exceptionally excellent (confidence level of 99.88%) if an energy shift of about 2 MeV in the rho-omega region is allowed.