The Scales of the Infrared

Understand

In theories with long-range forces like QED or perturbative gravity, loop corrections lead to vanishing amplitudes.

• There are two well-known procedures to address these infrared divergences: dressing of asymptotic states and inclusion of soft emission.
• Although both yield the same IR-finite rates, we point out that they are not equivalent since they encode different infrared scales.
• In particular, dressing states are independent of the resolution scale of radiation.