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Measurement of the spin-density matrix elements in exclusive electroproduction of \(\rho^0\) mesons at HERA

  • The ZEUS Collaboration
  • J. Breitweg et al.
Experimental physics

Abstract.

Exclusive electroproduction of \(\rho^0\) mesons has been measured using the ZEUS detector at HERA in two \(Q^2\) ranges, \(0.25 < Q^2 < 0.85\) GeV\(^2\) and \(3< Q^2 < 30\) GeV\(^2\). The low-\(Q^2\) data span the range \(20 < W < 90\) GeV; the high-\(Q^2\) data cover the \(40 < W < 120\) GeV interval. Both samples extend up to four-momentum transfers of \(|t|=0.6\) GeV\(^2\). The distribution in the azimuthal angle between the positron scattering plane and the \(\rho^0\) production plane shows a small but significant violation of s-channel helicity conservation, corresponding to the production of longitudinally polarised (i.e. helicity zero) \(\rho^0\) mesons from transverse photons. Measurements of the 15 combinations of spin-density matrix elements which completely define the angular distributions are presented and discussed.

Keywords

Matrix Element Angular Distribution Azimuthal Angle Production Plane Significant Violation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • The ZEUS Collaboration
  • J. Breitweg et al.
    • 1
  1. 1.Argonne National Laboratory, Argonne, IL, USAUS

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