Measurement of the CP properties of Higgs boson interactions with $$\tau $$-leptons with the ATLAS detector

A study of the charge conjugation and parity ($CP$) properties interaction between Higgs boson $\tau$-leptons is presented. The based on a measurement $CP$-sensitive angular observables defined by visible decay products $\tau$-lepton decays, where at least one hadronic required. analysis uses 139 fb$^{-1}$ proton$-$proton collision data recorded centre-of-mass energy $\sqrt{s}= 13$ TeV with ATLAS detector Large Hadron Collider. Contributions from $CP$-violating interactions are described single mixing angle parameter $\phi_{\tau}$ in generalised Yukawa interaction. Without assuming Standard Model hypothesis for $H\rightarrow\tau\tau$ signal strength, measured to be $9^{\circ} \pm 16^{\circ}$, an expected value $0^{\circ} 28^{\circ}$ 68% confidence level. pure $CP$-odd disfavoured level 3.4 standard deviations. results compatible predictions Model.