Much ado about nothing: vacuum and renormalization on the light-front

Abstract

In the first part of my lectures, I will use the example of deep-inelastic scattering to explain why light-front coordinates play a distinguished role in many high energy scattering experiments. After a brief introduction into the concept of light-front quantization, I will show that the vacuum for any light-front Hamiltonian is trivial, i.e. the same as for non-interacting fields. In the rest of my lectures, I will discuss several toy models in 1+1 and 3+1 dimensions and discuss how effective light-front Hamiltonians resolve the apparent paradox that results from having a trivial light-front vacuum.