The scalar mesons in multi-channel $\pi\pi$ scattering and decays of the $\psi$ and $\Upsilon$ families

Abstract

The $f_0$ mesons are studied in a combined analysis of data on the isoscalar S-wave processes $\pi\pi\to\pi\pi,K\overline{K},\eta\eta$ and on decays $J/\psi\to\phi(\pi\pi, K\overline{K})$, $\psi(2S)\to J/\psi(\pi\pi)$, and $\Upsilon(2S)\to\Upsilon(1S)\pi\pi$ from the Argus, Crystal Ball, CLEO, CUSB, DM2, Mark II, Mark III, and BES II collaborations. The method of analysis, based on analyticity and unitarity and using an uniformization procedure, is set forth with some details. Some spectroscopic implications from results of the analysis are discussed.Comment: Lecture read by Yu. Surovtsev at the Helmholtz International Summer School "Physics of Heavy Quarks and Hadrons - 2013", July 2013, Dubna, Russi