The soft limits of scattering amplitudes have been extensively studied due to their essential
role in the computation of physical observables in collider physics. The universal …

Here, we review the most recent progress in our understanding of quantum mechanical
observables in cosmology in the perturbative regime. It relies on an approach that considers …

A bstract Recent years have seen the emergence of a new understanding of scattering
amplitudes in the simplest theory of colored scalar particles—the Tr (ϕ 3) theory—based on …

A bstract We show that color-kinematics duality is a manifest property of the equations of
motion governing currents and field strengths. For the nonlinear sigma model (NLSM), this …

A bstract We systematically explore the space of scalar effective field theories (EFTs)
consistent with a Lorentz invariant and local S-matrix. To do so we define an EFT …

These lectures are a brief introduction to scattering amplitudes. We begin with a review of
basic kinematical concepts like the spinor helicity formalism, followed by a tutorial on …

A bstract We derive new amplitudes relations revealing a hidden unity among a wideranging
variety of theories in arbitrary spacetime dimensions. Our results rely on a set of Lorentz …

A bstract We present the Standard Model Effective Field Theories (SMEFT) from purely on-
shell arguments. Starting from few basics assumptions such as Poincaré invariance and …

A bstract We derive positivity bounds for scattering amplitudes of particles with arbitrary spin
using unitarity, analyticity and crossing symmetry. The bounds imply the positivity of certain …

A bstract We apply on-shell methods to the bottom-up construction of electroweak
amplitudes, allowing for both renormalizable and non-renormalizable interactions. We use …