Exclusive electroproduction of phi mesons at 4.2 GeV

TL;DR

This study investigates exclusive phi meson electroproduction at 4.2 GeV, analyzing cross sections and t-slope behavior to understand vector meson formation and compare with previous photoproduction data.

Contribution

It provides new measurements of phi meson production cross sections and t-slope dependence over a range of Q^2 and W, integrating with existing data for a comprehensive picture.

Findings

t-slope decreases with vector meson formation time below 2 fm

Measured b_phi = 2.27 +- 0.42 GeV^-2 at Q^2=0.6 fm

Cross section scales as W^{0.2+-0.1}, consistent with photoproduction

Abstract

We studied the exclusive reaction e p --> e' p' phi using the phi --> K^+ K^- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CLAS detector at Jefferson Lab. Our experiment covers the range in Q^2 from 0.7 to 2.2 GeV^2, and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of phi production on the proton. Our measurement shows the expected decrease of the t-slope with the vector meson formation time c Delta tau below 2 fm. At = 0.6 fm, we measure b_phi = 2.27 +- 0.42 GeV^-2. The cross section dependence on W as W^{0.2+-0.1} at Q^2 = 1.3 GeV^2 was determined by comparison with phi production at HERA after correcting for threshold effects. This is the same dependence as observed in photoproduction.