1:30 pm VIA ZOOM
Signs, Spin, SMEFT: Using Amplitudes to Constrain New Physics, Grant Remmen, KITP
Hints of new physics are encoded as higher-dimension operators in effective field theory. The couplings of these operators, "dial settings" in the low-energy laws of physics, can be bounded using methods independent of the ultraviolet completion, relying only on principles like unitarity of quantum mechanics, analytic properties of scattering amplitudes, and causality. In this talk, I will show how such infrared consistency techniques can be used to constrain operators in the Standard Model EFT, constructing bounds for quartic bosonic and fermionic operators at mass dimension 8. Furthermore, using the Jacob-Wick partial wave expansion to construct novel dispersion relations, I will derive bounds for four-fermi operators at mass dimension 6, overcoming a theoretical barrier to constraining these phenomenologically important operators. These constraints give compelling near-term experimental implications for CP and flavor violation as well as collider physics, and provide us with powerful means to test the tenets of quantum field theory itself.