A bstract Recent work has shown how on-shell three-point amplitudes in gauge theory and gravity, representing the coupling to massive particles, correspond classical limit curvature spinors of linearised solutions. This connection, made explicit via KMOC formalism split metric signature, turns double copy scattering into Here, we extend this framework universal massless sector supergravity, whi...

Scattering amplitudes in the maximally supersymmetric N = 4 gauge theory are known to possess some remarkable features. The reasons for this are not completely understood, but some possible candidates are: the integrability properties of the theory, the existence of a gravitational dual and the existence of a twistor space description. I will not try to give a detailed description of the N = 4 ...

We introduce a new technique to generate scattering amplitudes at one loop. Traditional tree algorithms, which handle diagrams with fixed momenta, are promoted to generators of loop-momentum polynomials that we call open loops. Combining open loops with tensor-integral and Ossola-Papadopoulos-Pittau reduction results in a fully flexible, very fast, and numerically stable one-loop generator. As ...

Four simple assumptions for scattering amplitudes are proposed in order to derive dual amplitudes. The assumptions are conventional except the one which states that each term of an amplitude, corresponding to a certain combination of Regge poles ins, t and u channels, is constructed by a triple product form of three unknown functions, U1 (t), {12 (s) and us (u). This is arrived at by an abstrac...

A method for the nonperturbative calculation of scattering amplitudes and cross sections is discussed in the context of light-cone quantization. The Lanczos-based recursion method of Haydock is suggested for the computation of matrix elements of the resolvent for the light-cone Hamiltonian, from which the T -matrix can be constructed. The scattering of composite particles is handled by a genera...

We consider the calculation of scattering amplitudes in field theories dual to Lifshitz spacetimes. These amplitudes provide an interesting probe of the IR structure of the field theory; our aim is to use them to explore the observable consequences of the singularity in the spacetime. We assume the amplitudes can be related by T-duality to a Wilson loop, as in the AdS case, and determine the bu...

By using the Boltzmann equation describing the relaxation of colour excitations in the QCD plasma, we obtain effective amplitudes for the ultrasoft colour fields carrying momenta of order g2T . These amplitudes are of the same order in g as the hard thermal loops (HTL), which they generalize by including the effects of the collisions among the hard particles. The ultrasoft amplitudes share many...

Properties of scalar–isoscalar mesons are analysed in an unitary model using separable interactions in three decay channels: ππ , KK and an effective 2π2π. We obtain different solutions by fitting various data on the ππ and KK phase shifts and inelasticities including the CERN-Cracow-Munich measurements of the πp↑ → π+π−n reaction on a polarized target. Analytical structure of the meson-meson m...

This is a short and simple introduction into perturbiners, that is, the solutions of field equations which are generating functions for tree amplitudes. The perturbiners have been constructed in Yang-Mills, in SUSY Yang-Mills, in gravity, and in sin(h)-Gordon.

It is well known that the high order calculations of the observables within the perturbation theory has the serious difficulties (especially, if we take into account the polarization effects). Method of the direct calculation of amplitudes simplifies these calculations essentially. There is an even number (2N) of fermions in initial and final state for any reaction with Dirac particles. Therefo...