Number of constituents in a proton, the diffractive excitation and the Chou-Yang model

The single diffractive excitation in a constituent model is shown, under the Glauber approximation, to vanish in the limit of an infinite number of constituents. In this limit the model is reduced to the Chou-Yang model. Since the proton-proton scattering data at ISR energies show the large single diffractive excitation, the Chou-Yang model would have a difficulty to describe diffractive excitation. (author)