Speaker
Description
Axions and axion-like particles (ALPs) remain among the most compelling solutions to the strong CP problem and viable dark matter candidates. As experimental sensitivities at the intensity and cosmic frontiers increase, matching theoretical precision in effective field theory (EFT) is paramount. In this talk, we present a comprehensive, multi-loop EFT framework for ALPs. First, we address the subtleties of chiral flavor currents in dimensional regularization. Working within the Breitenlohner-Maison-'t Hooft-Veltman (BMHV) scheme, we demonstrate the emergence of evanescent operators and determine the finite renormalization required to restore four-dimensional Ward identities. Second, we apply these robust EFT techniques to flavor-changing neutral currents, specifically $B \to K a$ transitions followed by hadronic and leptonic decays. By calculating the anomalous dimension matrix up to two-loop order and matching at the electroweak scale, we explicitly track the cancellation of ultraviolet and infrared divergences. Finally, we provide updated bounds for various UV completions (KSVZ, DFSZ, and Flaxion models), establishing stringent constraints on the axion decay constant $f_a$ and identifying new parameter space accessible to upcoming searches.