S-wave $pi^0$ production In pp Collision In A Covariant OBE Model

The total cross section for the pp to pp $pi^0$ reaction at energies close to threshold is calculated in a covariant one-boson-exchange model. The amplitudes for the elementary BN to N$pi^0$ processes are taken to be the sum of s, u and t pole terms. The main contributions to the primary productionamplitude is due to a sigma meson exchange. Both the scale and energy dependence of the cross section are perfectly reproduced.