An alternative parametrization of the pion form factor and the mass and width of rho(770)

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dc.creatorLichard, Peter
dc.creatorVojik, Martin
dc.date2006-11-13
dc.date.accessioned2026-07-07T07:32:04Z
dc.date.available2026-07-07T07:32:04Z
dc.descriptionIn 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.
dc.identifierhttps://arxiv.org/abs/hep-ph/0611163
dc.identifierhttp://arxiv.org/abs/hep-ph/0611163
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/118983
dc.subjectHigh Energy Physics - Phenomenology
dc.titleAn alternative parametrization of the pion form factor and the mass and width of rho(770)
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