Near-threshold $omega$ and $phi$ meson productions in $pp$ collisions


Abstract in English

Using a relativistic effective Lagrangian at the hadronic level, near-threshold $omega$ and $phi$ meson productions in proton proton ($pp$) collisions, $p p to p p omega/phi$, 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 $omega$ and $phi$ angular distribution data are used to constrain further the model parameters. For the $p p to p p omega$ 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 $pi^- p to omega n$ 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 two. As for the $p p to p p phi$ 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 $phi NN$ coupling constants. Further measurements of the energy dependence of the total cross section near threshold energies should help to constrain better the $phi NN$ coupling constant.

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