Classical off-shell currents

Abstract

We consider tree-level off-shell currents of two massive particles and $n$ massless bosons in the classical limit, which can be fused into the classical limit of $n+2$ scattering amplitudes. We show that dressing up the current with coherent wave-functions associated with the massive particles leads to the recently proposed Worldline Quantum Field Theory (WQFT) path integral. The currents thus constructed encode solutions of classical equations of motion so they can be applied to contexts where the classical limit is relevant, including hard thermal loops. We give several examples of these currents in scalar, gauge and gravitational theories.

28 pages, v2: clarifications in Sec.2, references added, typos fixed, matches published version

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Cited by in corpus (7)

• One-loop Gravitational Bremsstrahlung and Waveforms from a Heavy-Mass Effective Field Theory
• Resummed spinning waveforms from five-point amplitudes
• Classical Spin Gravitational Compton Scattering
• Recursion in the classical limit and the neutron-star Compton amplitude
• Classical Double Copy of Spinning Worldline Quantum Field Theory
• Loop-level double-copy for massive fermions in the fundamental
• The gravitational Compton amplitude from flat and curved spacetimes at second post-Minkowskian order