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تسجيل مستخدم جديدExclusive electroproduction of two pions at HERA
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The exclusive electroproduction of two pions in the mass range 0.4 < M{pi}{pi} < 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 GeV2, 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{pi}{pi})|, 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} rightarrow {pi}{pi})/{sigma}({rho}) and {sigma}({rho} rightarrow {pi}{pi})/{sigma}({rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e+e- rightarrow {pi}+{pi}-.
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