364 articles – 2951 Notices  [english version]
 HAL : in2p3-00005180, version 1
 European Physical Journal C 13 (2000) 371-396
 Elastic Electroproduction of $\rho$ Mesons at HERA
 H1 Collaboration(s)
 (2000)
 The elastic electroproduction of rho mesons is studied at HERA with the H1 detector for a photon virtuality in the range 1 Q^2 60 GeV^2 and for a hadronic centre of mass energy in the range 30 W 140 GeV. The shape of the pipi mass distribution in the rho resonance region is measured as a function of Q^2. The full set of rho spin density matrix elements is determined, and evidence is found for a helicity flip amplitude at the level of 8 +- 3 % of the non-flip amplitudes. Measurements are presented of the dependence of the cross section on Q^2, W and t (the four-momentum transfer squared to the proton). They suggest that, especially at large Q^2, the gamma^*p cross section develops a stronger W dependence than that expected from the behaviour of elastic and total hadron-hadron cross sections.
 Thème(s) : Physique/Physique des Hautes Energies - Expérience
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 in2p3-00005180, version 1 http://hal.in2p3.fr/in2p3-00005180 oai:hal.in2p3.fr:in2p3-00005180 Contributeur : Magali Damoiseaux <> Soumis le : Mardi 4 Juillet 2000, 09:18:43 Dernière modification le : Mardi 4 Juillet 2000, 09:18:43