Unitarity of Minkowski nonlocal theories made explicit

Alexey S. Koshelev, Anna Tokareva
2021 Physical Review D  
In this work we explicitly show that the perturbative unitarity of analytic infinite derivative scalar field theories can be achieved using a modified prescription for computing scattering amplitudes. The crux of the new prescription is the analytic continuation of a result obtained in the Euclidean signature to the Minkowski external momenta. We intensively elaborate an example of a nonlocal ϕ 4 model for various infinite derivative operators. General UV properties of amplitudes in nonlocal theories are discussed.
doi:10.1103/physrevd.104.025016 fatcat:zbxgbhjzkjbsxlii5jnaklc7zu