Exclusive electroproduction of two pions at HERA

Abstract

The exclusive electroproduction of two pions in the mass range 0.4 < Mππ < 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(Mππ)|, assuming that the studied mass range includes the contributions of the ρ, ρ' and ρ" vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios σ(ρ' \rightarrow ππ)/σ(ρ) and σ(ρ" \rightarrow ππ)/σ(ρ) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e+e- \rightarrow π+π-.

24 pages, including 11 figures

References in corpus (3)

• Precise measurement of the e+ e- to pi+ pi- (gamma) cross section with the Initial State Radiation method at BABAR
• Diffractive Electroproduction of rho and phi Mesons at HERA
• Exclusive photoproduction of {\bf ${\rm Y}$} mesons at HERA

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• ${\pi }^{+}{\pi }^{-}$ and ${\pi }^0{\pi }^0$ pair production in photon-photon and in ultraperipheral ultrarelativistic heavy ion collisions
• The radial Regge trajectories and leptonic widths of the isovector mesons
• Exploring Baryon Resonances with Transition Generalized Parton Distributions: Status and Perspectives
• Photoproduction of K${}^{+}$K${}^{-}$ pairs in ultra-peripheral collisions
• Role of $\rho -\omega$ interference in semileptonic $B\to {\pi }^{+}{\pi }^{-}\ell {\bar{\nu }}_{\ell }$ decays