How to pin down the CP quantum numbers of a Higgs boson in its tau decays at the LHC

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We investigate how the CP quantum numbers of a neutral Higgs boson or spin-zero resonance, produced at the CERN Large Hadron Collider, can be determined in its tau-pair decay mode.

• We use a method developed in an earlier paper based on the distributions of two angles and apply it to the major 1-prong tau decays.
• We show for the resulting dilepton, lepton-pion, and two-pion final states that appropriate selection cuts significantly enhance the discriminating power of these observables.
• From our analysis we conclude that, provided a Higgs boson will be found at the LHC, it appears feasible to collect the event numbers needed to discriminate between a CP-even and -odd Higgs boson and/or between Higgs boson(s) with CP-conserving and CP-violating couplings after several years of high-luminosity runs.