Double - spin asymmetries in the cross section of ρ 0 and φ production at intermediate energies

نویسندگان

  • L. De Nardo
  • E. De Sanctis
  • E. Devitsin
  • P. Di Nezza
  • M. Düren
چکیده

Double-spin asymmetries in the cross section of electroproduction of ρ and φ mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in exclusive ρ electroproduction on the proton exhibits a positive tendency. This is consistent with theoretical predictions that the exchange of an object with unnatural parity contributes to exclusive ρ electroproduction by transverse photons. The photoabsorption asymmetry on the deuteron is found to be consistent with zero. Double-spin asymmetries in ρ and φ meson electroproduction by quasi-real photons were also found to be consistent with zero; the asymmetry in the case of the φ meson is compatible with a theoretical prediction which involves ss̄ knockout from the nucleon.

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تاریخ انتشار 2003