Electroproduction of φ meson from proton and the strangeness in the nucleon

We analyze the process e p → e p φ near the threshold within uud-ss̄ cluster model as a probe of the strangeness content of proton. Our consideration is based on the relativistic harmonic oscillator quark model which takes into account the Lorentz-contraction effect of the hadron wavefunctions. We find that the knockout mechanisms are comparable to the diffractive production of vector-meson-dominance model when only (3–5)% strange quark admixture is assumed, which should be compared with (10–20)% of the nonrelativistic quark model prediction. The cross sections of the uudand ss̄-knockout processes have qualitatively different dependence on the four-momentum transfer squared to the proton and may be distinguished experimentally. We also briefly discuss a way to determine the strangeness content of proton in 5-quark cluster model. Typeset using REVTEX ∗Permanent address: Bogoliubov Theoretical Laboratory, Joint Institute for Nuclear Research, 141980 Dubna, Russia. †Present address: Institut für Theoretische Physik, Physik Department, Technische Universität München, James–Franck–Straße, D-85747 Garching, Germany. 1