The Boostless Bootstrap: Amplitudes without Lorentz boosts

Understand

Poincar\'e invariance is a well-tested symmetry of nature and sits at the core of our description of relativistic particles and gravity.

• At the same time, in most systems Poincar\'e invariance is not a symmetry of the ground state and is hence broken spontaneously.
• This phenomenon is ubiquitous in cosmology where Lorentz boosts are spontaneously broken by the existence of a preferred reference frame in which the universe is homogeneous and isotropic.
• This motivates us to study scattering amplitudes without requiring invariance of the interactions under Lorentz boosts.