Speaker
Dr
Justyna Tomaszewska
(DESY)
Description
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.
Author
Olaf Behnke
(DESY)
