Speaker
Description
The matching of UV models on their low-energy EFT can be obtained from a dispersion relation, analogous to the one leading to positivity constraints but generalised beyond four-point amplitudes. Introduced in 2308.00035, this method is distinct from those based on the (functional) effective action and on (off- or on-shell) amplitudes. It takes cut amplitudes as input. In particular, one-loop matching essentially requires only tree-level inputs. All EFT orders can be obtained at once, from an integral along the cut which may however be difficult to perform. This extracts the hard region of the un-cut loop, so that no EFT contribution has to be calculated and subtracted. On-shell tree-level EFT amplitudes are obtained which fully characterise the low-energy theory. Some computations are facilitated and new insight is gained.
