Chia-Hsien Shen (Uppsala U.)

Scattering Amplitudes for Classical and Quantum Effective Field Theory

Abstract: From the Higgs boson to astrophysical black holes, the length scales of fundamental physics span dozens of orders of magnitude. Despite this vast range, many key phenomena can be systematically described within the universal framework of effective field theory (EFT). While EFT has been well-established for decades, new experimental progress continue to present both challenges and opportunities. In this talk, I will introduce the ERC project AmpEFT to address these issues through the lens of scattering amplitudes. This modern approach has led to new structures, simplicity, and state-of-the-art precision in the search for new physics beyond the Standard Model and gravitational wave physics. I will present new progress in this project. The first one classifies the direction of renormalization group flow in EFT, in the spirit of the a-theorem in CFT, and address the loop effect on the so-called positivity bounds. The second one aims to systematically calculate the long-distance correction in gravitational-wave emission, analogous to the Sommerfeld enhancement in dark matter detection.