Testing CP violation in ZZH interactions at the LHC

We study genuine CP-odd observables at the LHC to test the CP property of the ZZH interaction for a Higgs boson with mass below the threshold to a pair of gauge bosons via the process pp→ZH→ℓ+ℓ−bb¯. We illustrate the analysis by including a CP-odd ZZH coupling, and show how to extract the CP asymmetries in the signal events. After selective kinematical cuts to suppress the SM backgrounds plus an optimal log-likelihood analysis, we find that, with a CP violating coupling b˜≃0.25, a CP asymmetry may be established at a 3σ (5σ) level with an integrated luminosity of about 30 (50) fb−1 at the LHC.