HEFT approach to investigate the muon g−2 anomaly at a muon collider

In a previous work, Buttazzo and Paradisi [], pointed out that heavy new physics (NP) contributions to lepton dipole moments and high-energy cross sections of lepton pairs into Higgs and γ/Z bosons are connected, if the electroweak symmetry breaking is realized linearly. As a consequence, a multi-TeV muon collider would provide a unique test of NP in the muon g−2 through the study of high-energy processes such as μ+μ−→h+γ/Z. Since the analysis involved a Standard Model effective field theory (SMEFT) approach to Higgs processes, it could also be studied by the more general Higgs EFT (HEFT) formulation. We compute the modification of the high-energy cross section μ+μ−→h+γ/Z and h→μ+μ−+γ/Z decay using the dimension-6 HEFT Lagrangian and compare them with the SMEFT analysis. We find that, within the current HEFT analysis, there are plausible scenarios where the HEFT approach could lead to a higher sensitivity to test the NP contributions in the muon g−2. However, a more precise knowledge of the new HEFT parameters is needed for a definite conclusion, which motivates the search for complementary measurements. Published by the American Physical Society 2025