Orateur
Brando Bellazini
Description
Long-range interactions in four-dimensional flat spacetime pose a challenge for positivity bounds and S-matrix bootstrap programs, because infrared divergences trivialize ordinary scattering amplitudes. In this talk, I will introduce stripped, or detector, amplitudes: IR-finite avatars of standard amplitudes that retain analyticity, crossing symmetry, and Regge boundedness, while depending on a physical detector scale. When this scale is taken exponentially smaller than all other scales in the problem, detector amplitudes also obey a suitable form of unitarity. This makes it possible to derive IR-finite positivity bounds for effective field theories in the presence of long-range interactions.