Loop expansion in light-cone φ4 field theory

Based on the path integral quantization of the light-cone φ4 field theory in 1+1 dimensions, a loop expansion is implemented. The effective potential as a function of the zero-mode field ω is calculated up to two loop order and its derivative with respect to ω is used to determine the vacuum expectation value of the field φ. The critical coupling constant at the occurrence of the spontaneous symmetry breaking is consistent with that obtained in the ordinary instant-form field theory. The critical exponents which describe the behavior of the susceptibility and the vacuum expectation value of φ near the critical point are evaluated from the effective potential. The one loop diagrams for the connected Green's function are calculated in momentum space. The relevant equal-time correlation function is shown to be closely related