Near-threshold ω and φ meson productions in pp collisions

Using a relativistic effective Lagrangian at the hadronic level, near-threshold ω- and φ-meson productions in proton-proton (pp) collisions, pp⃗ppω/φ, are studied within the distorted wave Born approximation. Both initial and final state pp interactions are included. In addition to total cross section data, both ω and φ angular distribution data are used to constrain further the model parameters. For the pp⃗ppω reaction, we consider two different possibilities: with and without the inclusion of nucleon resonances. The nucleon resonances are included in a way to be consistent with the π^-p⃗ωn reaction. It is shown that the inclusion of nucleon resonances can describe the data better overall than without their inclusion. However, the SATURNE data in the range of excess energies Q<31 MeV are still underestimated by about a factor of 2. As for the pp⃗ppφ reaction, it is found that the presently limited available data from DISTO can be reproduced by four sets of values for the vector and tensor φNN coupling constants. Further measurements of the energy dependence of the total cross section near threshold energies should help to constrain better the φNN coupling constant.