Speaker
Description
CP-violating probes are among the most promising and yet relatively unexplored ways to look for Axion-like particles (ALPs) and to investigate their phenomenology.
Starting from the most general dimension-5, $SU(3)_{\text{c}} \times U(1)_{\text{em}}$ invariant effective Lagrangian for a CP-violating ALP at the electroweak (EW) scale, we discuss two relevant phenomenological frameworks.
In the first one, the impact of heavy ALPs ($m_a \gg 1$ GeV) on low-energy CP-violating observables is analyzed in detail.
In the second one we rather consider lighter ALPs ($m_a \ll 1$ GeV). In this case, QCD can no longer be treated perturbatively and the CPV interactions of ALPs are included in a chiral perturbation theory setup.
Given the resemblance between our setup and the HEFT one, where the Higgs field is treated as a singlet, parallels between the two scenarios are drawn.
