2021/08/13 by Joe Davighi, Scott Melville, Tevong You
Mathematics · Physics and Astronomy · #Amplitude #Black Holes and Theoretical Physics #Causality (physics) #Cosmology and Gravitation Theories #Helicity #Limit (mathematics) #Lorentz covariance #Lorentz transformation #Mathematical analysis #Mathematical physics #Mathematics #Particle physics theoretical and experimental studies #Physics #Quantum mechanics #Scattering amplitude #Sign (mathematics) #Unitarity #hep-ph #hep-th
paper · pdf · doi:10.1007/jhep02(2022)167
33 pages + appendices, 1 figure, 1 table
arxiv created 2021/08/13 · openalex publication_date 2022/02/01 · arxiv updated 2022/03/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We derive new effective field theory (EFT) positivity bounds on the elastic 2→2 scattering amplitudes of massive spinning particles from the standard UV properties of unitarity, causality, locality and Lorentz invariance. By bounding the t derivatives of the amplitude (which can be represented as angular momentum matrix elements) in terms of the total ingoing helicity, we derive stronger unitarity bounds on the s- and u-channel branch cuts which determine the dispersion relation. In contrast to previous positivity bounds, which relate the t-derivative to the forward-limit EFT amplitude with no t derivatives, our bounds establish that the t-derivative alone must be strictly positive for sufficiently large helicities. Consequently, they provide stronger constraints beyond the forward limit and can be used to constrain dimension-6 interactions with a milder assumption about the high-energy growth of the UV amplitude.