26-30 March 2012
University of Bonn
Europe/Berlin timezone

Exclusive Electroproduction of two Pions at HERA

28 Mar 2012, 16:20
Lecture Hall, Institute for Applied Physics (University of Bonn)

Lecture Hall, Institute for Applied Physics

University of Bonn

Diffraction and vector mesons Diffraction and vector mesons


Dr Justyna Tomaszewska (DESY)


The exclusive electroproduction of two pions in the mass range 0.4 < M(pipi) < 2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. The analysis was carried out in the kinematic range of 2 < Q2 < 80 GeV2, 32 < W <180 GeV and |t|<0.6 GeV, where Q2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |F(M(pipi)|, assuming that the studied mass range includes the contributions of the rho, rho' and rho'' vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios sigma(rho'->pipi)\sigma(rho) and sigma(rho''->pipi)/sigma(rho) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e+e- -> pipi.

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