Double-spin asymmetries in the cross section of $\rho^0$ and $\phi$ production at intermediate energies

Abstract

Abstract. Double-spin asymmetries in the cross section of electroproduction of ρ 0 and φ mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in exclusive ρ 0 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 0 electroproduction by transverse photons. The photoabsorption asymmetry on the deuteron is found to be consistent with zero. Double-spin asymmetries in ρ 0 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 ss knockout from the nucleon.