Covariant Phase Space and Soft Factorization in Non-Abelian Gauge Theories

Understand

We perform a careful study of the infrared sector of massless non-abelian gauge theories in four-dimensional Minkowski spacetime using the covariant phase space formalism, taking into account the boundary contributions arising from the gauge sector of the theory.

• Upon quantization, we show that the boundary contributions lead to an infinite degeneracy of the vacua.
• The Hilbert space of the vacuum sector is not only shown to be remarkably simple, but also universal.
• We derive a Ward identity that relates the n-point amplitude between two generic in- and out-vacuum states to the one computed in standard QFT.