Speaker
Description
Axion-Like Particles (ALPs) appear as pseudo-Goldstone bosons in many Standard Model extensions with a spontaneous breaking of a global symmetry and can be searched for in large mass range.
At low energies, a Standard Model extension with an ALP can be parametrised in terms of an ALP Effective Field Theory (ALP EFT), which can be either linear or chiral, depending on the assumptions on the Higgs sector.
In the linear case the strongest ALP coupling to the fermionic sector is the ALP-top coupling, due to the large top mass. We use high-energy LHC probes to constrain this coupling and examine both direct searches for ALP production in association with a top-pair, and the indirect probes of top quark pair production and Di-boson production, both mediated by an off-shell ALP.
In the chiral case, the EFT also contains tree-level couplings of an ALP to three bosons which give rise to the ALP-induced production of two Higgs bosons in association with a Z boson. We examine the existing constraints from di-Higgs searches at Run 2 of the LHC and propose a dedicated search for HHZ states. Furthermore, we compare the chiral EFT predictions with the contributions from top quark loops in the linear case.
Finally, I will explain how measurements of multi-boson final states can be used to perform a global fit to ALP-multiboson couplings in the linear ALP EFT.
