Self-energy effect on the rotation symmetry in the light-cone-quantized scalar field scattering.

Abstract

Rotational invariance is violated in the light-cone quantization method when the Fock space is truncated for practical calculations. To what extent the rotation symmetry is broken in the light-cone quantization approach can be quantified by calculating the explicit rotation dependence of the two-body scattering phase shifts. We analyze the scattering phase shifts in a simple scalar field model, extending the light-cone ladder approximation to the lowest order light-cone Tamm-Dancoff approximation in which the self-energy corrections are incorporated. We find that the self-energy effects significantly restore the rotation symmetry. Also, these effects make the phase shifts stabilize as the coupling constant grows. This is in a good agreement with the previous bound state results that the self-energy effects are as repulsive as relativistic kinematic corrections and retardation effects.