S-ware π0 production in pp collisions in a OBE model Original Research Article

The total cross section for the pp → ppπ0 reaction at energies close to threshold is calculated using a covariant one-boson-exchange model, where a boson B created on one of the incoming protons is converted into a neutral pion on the second. The amplitudes for the conversion processes, BN → Nπ0, are taken to be the sum of s, u and t-channel pole terms. The main contributions to the primary production amplitude is due to an effective isoscalar σ meson pole in a t-channel, which is enhanced strongly due to offshellness. With this contribution included the model reproduces, both the scale and energy dependence of the cross section.