  Analyses of high energy elastic pp and $\bar pp$ scattering data from CERN
ISR and SPS Collider seem to provide strong evidence in favor of the gauged
nonlinear sigma-model of the nucleon. This model describes the nucleon as a
topological soliton and introduces the vector mesons omega, rho, a1 as gauge
bosons. The model, however, needs to be extended to include an explicit quark
sector, where left and right quarks interact via a scalar field. A critical
behavior of the scalar field results in a phase transition to a condensed
quark-antiquark ground state. The latter can provide the outer cloud of the
nucleon, which is responsible for diffraction scattering. If the nucleon is
probed deeper via high energy elastic scattering, then evidence for the phase
transition may emerge from a rapid change in the behavior of the differential
cross-section.
