Exclusive electroproduction of PHI mesons at HERA

Exclusive electroproduction of ϕ mesons has been studied in e ± p e ± p collisions at s = 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb −1 65.1 pb −1 . The γ ∗ p γ ∗ p cross section is presented in the kinematic range 2 GeV 2 2 2 2 GeV 2 Q 2 70 GeV 2 , 35 GeV 35 GeV W 145 GeV and |t| 2 | t | 0.6 GeV 2 . The cross sections as functions of Q 2 Q 2 , W , t and helicity angle θ h θ h are compared to cross sections for other vector mesons. The ratios R of the cross sections for longitudinally and transversely polarized virtual photons are presented as functions of Q 2 Q 2 and W . The data are also compared to predictions from theoretical models.