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

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jats:titleAbstract</jats:title>jats:pA study of the charge conjugation and parity (jats:inline-formulajats:alternativesjats:tex-math$$\textit{CP}$$</jats:tex-math><mml:math xmlns:mml=""> mml:miCP</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>) properties of the interaction between the Higgs boson and jats:inline-formulajats:alternativesjats:tex-math$$\tau $$</jats:tex-math><mml:math xmlns:mml=""> mml:miτ</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-leptons is presented. The study is based on a measurement of jats:inline-formulajats:alternativesjats:tex-math$$\textit{CP}$$</jats:tex-math><mml:math xmlns:mml=""> mml:miCP</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-sensitive angular observables defined by the visible decay products of jats:inline-formulajats:alternativesjats:tex-math$$\tau $$</jats:tex-math><mml:math xmlns:mml=""> mml:miτ</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-leptons produced in Higgs boson decays. The analysis uses 139 fbjats:inline-formulajats:alternativesjats:tex-math$$^{-1}$$</jats:tex-math><mml:math xmlns:mml=""> mml:msup <mml:mrow /> mml:mrow mml:mo-</mml:mo> mml:mn1</mml:mn> </mml:mrow> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> of proton–proton collision data recorded at a centre-of-mass energy of jats:inline-formulajats:alternativesjats:tex-math$$\sqrt{s}= 13$$</jats:tex-math><mml:math xmlns:mml=""> mml:mrow mml:msqrt mml:mis</mml:mi> </mml:msqrt> mml:mo=</mml:mo> mml:mn13</mml:mn> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> TeV with the ATLAS detector at the Large Hadron Collider. Contributions from jats:inline-formulajats:alternativesjats:tex-math$$\textit{CP}$$</jats:tex-math><mml:math xmlns:mml=""> mml:miCP</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-violating interactions between the Higgs boson and jats:inline-formulajats:alternativesjats:tex-math$$\tau $$</jats:tex-math><mml:math xmlns:mml=""> mml:miτ</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-leptons are described by a single mixing angle parameter jats:inline-formulajats:alternativesjats:tex-math$$\phi _{\tau }$$</jats:tex-math><mml:math xmlns:mml=""> mml:msub mml:miϕ</mml:mi> mml:miτ</mml:mi> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula> in the generalised Yukawa interaction. Without constraining the jats:inline-formulajats:alternativesjats:tex-math$$H\rightarrow \tau \tau $$</jats:tex-math><mml:math xmlns:mml=""> mml:mrow mml:miH</mml:mi> mml:mo→</mml:mo> mml:miτ</mml:mi> mml:miτ</mml:mi> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> signal strength to its expected value under the Standard Model hypothesis, the mixing angle jats:inline-formulajats:alternativesjats:tex-math$$\phi _{\tau }$$</jats:tex-math><mml:math xmlns:mml=""> mml:msub mml:miϕ</mml:mi> mml:miτ</mml:mi> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula> is measured to be jats:inline-formulajats:alternativesjats:tex-math$$9^{\circ } \pm 16^{\circ }$$</jats:tex-math><mml:math xmlns:mml=""> mml:mrow mml:msup mml:mn9</mml:mn> mml:mo∘</mml:mo> </mml:msup> mml:mo±</mml:mo> mml:msup mml:mn16</mml:mn> mml:mo∘</mml:mo> </mml:msup> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, with an expected value of jats:inline-formulajats:alternativesjats:tex-math$$0^{\circ } \pm 28^{\circ }$$</jats:tex-math><mml:math xmlns:mml=""> mml:mrow mml:msup mml:mn0</mml:mn> mml:mo∘</mml:mo> </mml:msup> mml:mo±</mml:mo> mml:msup mml:mn28</mml:mn> mml:mo∘</mml:mo> </mml:msup> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> at the 68% confidence level. The pure jats:inline-formulajats:alternativesjats:tex-math$$\textit{CP}$$</jats:tex-math><mml:math xmlns:mml=""> mml:miCP</mml:mi> </mml:math></jats:alternatives></jats:inline-formula>-odd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model.</jats:p>


Acknowledgements: We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TENMAK, Türkiye; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, Compute Canada and CRC, Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d’Avenir Labex, Investissements d’Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and MINERVA, Israel; Norwegian Financial Mechanism 2014–2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in Ref. [79].


5107 Particle and High Energy Physics, 51 Physical Sciences

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The European Physical Journal C

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