2025/12/15 by Haijun Yang, Yang, Haijun
Physics and Astronomy · #Particle physics theoretical and experimental studies #High-Energy Particle Collisions Research #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2512.13226
This proceedings presents a concise overview of the Higgs boson's charge-conjugation and parity (CP) properties and constraints on Effective Field Theory (EFT) operators, derived from the ATLAS experiment at the Large Hadron Collider (LHC). Using proton\textendashproton collision data with integrated luminosities of up to 140 fb-1 at √(s) = 13 TeV, the ATLAS collaboration systematically probe the CP nature of the Higgs boson's couplings to fermions (τ leptons, bottom quarks, and top quarks) and bosons (W, Z, and γ) across diverse decay final states. The EFT framework is used to parameterize Beyond the Standard Model (BSM) effects via dimension-6 operators, enabling model-independent constraints on CP violation and new physics scales. The main focus is comparison of measurement characteristics and sensitivity across different final states: (1) H → ττ (semileptonic/hadronic decays) for light fermion couplings; (2) H → γγ and H → bb in ttH/tH processes for heavy fermion couplings; (3) H → WW^* → lνlν, H → ZZ^* → 4l, and vector boson fusion (VBF) H → ττ/γγ for boson couplings; and (4) double Higgs (HH) production for self-couplings. All measurements are consistent with the Standard Model (SM) prediction of a CP-even Higgs boson (JCP = 0++), with no evidence of CP violation. The most stringent constraint on the CP-odd EFT parameter c_HW is obtained from VBF H → ττ (c_HW ∈ [-0.23, 0.70] at 95% CL), highlighting the unique sensitivity of this channel. Complementary constraints from other final states reinforce the robustness of SM consistency and provide a foundation for future searches.