Mrs Halina Abramowicz
Two pion exclusive electroproduction at HERA has been studied with the ZEUS detector using 82 pb-1 of integrated luminosity collected during 1998-2000. The analysis was carried out in the kinematic range of photon virtuality 2 < Q2 < 80 GeV2, gamma*p center-of-mass energy 40 < W < 180 GeV and two-pion invariant mass 0.4 < M(pipi) < 2.5 GeV. The pi+pi-invariant-mass distribution was analysed in terms of the pion electro-magnetic form factor, |F(M pi pi )| based on the contributions from three Vector Mesons, rho, rho' and rho''. The masses and widths of the resonances were obtained. The Q^2 dependence of the cross-section ratios sigma(rho)/sigma(rho') and sigma(rho'')/sigma(rho) was studied.
Prof. Collaboration ZEUS (Tel Aviv University)