Determination of the Higgs CP-mixing angle in the tau decay channels at the LHC including the Drell–Yan background

2014/08/31 by Stefan Berge, Werner Bernreuther, Sebastian Kirchner · 1 citation
Physics and Astronomy · #Calibration #Distribution (mathematics) #Gluon #Higgs boson #Large Hadron Collider #Luminosity #Mixing (physics) #Monte Carlo method #Neutrino Physics Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Resonance (particle physics) #hep-ex #hep-ph

paper · pdf · doi:10.1140/epjc/s10052-014-3164-0

published as Eur.Phys.J. C74 (2014) 11, 3164 · 27 pages, 11 figures, 1 table; journal version

openalex publication_date 2014/11/01 · arxiv created 2014/12/10 · arxiv updated 2014/12/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We investigate how precisely the CP nature of the 125 GeV Higgs-boson resonance h can be unraveled at the LHC in its decays to τ pairs, h → τ ^-τ ⁺ . We use a method which allows one to determine the scalar–pseudoscalar Higgs mixing angle φ _τ in this decay mode. This mixing angle can be extracted from the distribution of a signed angle, denoted by φ _CP^* , which we analyze for the major charged-prong τ decays. For definiteness, we consider Higgs-boson production by gluon fusion at NLO QCD. We take into account also the irreducible background from Drell–Yan production, Z^*/γ ^*→ τ τ , at NLO QCD. We compute, for the signal and background reactions, angular and energy correlations of the charged prongs and analyze which type of cuts suppress the Drell–Yan background. An important feature of this background is that its contribution to the distribution of our observable φ _CP^* is a flat line, also at NLO QCD. By separating the Drell–Yan τ events into two different sets, two different non-trivial φ _CP^* distributions are obtained. Based on this observation we propose to use these sets for calibration purposes. By Monte Carlo simulation we study also the effect of measurement uncertainties on this distribution. We estimate that the Higgs mixing angle φ _τ can be determined with our method to a precision of Δ φ _τ ≃ 14^∘ (5^∘ ) at the high-luminosity LHC (14 TeV) with an integrated luminosity of 500 fb ^-1 (3 ab ^-1 ).

Citations

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Determining theCPProperties of the Higgs Boson
• Determining the Structure of Higgs Couplings at the CERN Large Hadron Collider
• Determining theCPParity of Higgs Bosons via TheirτDecay Channels at the Large Hadron Collider
• Testing CP in the Bjorken process
• Using decay angle correlations to detect CP violation in the neutral Higgs sector
• Large tree-levelCPviolation ine+e−→tt¯H0in the two-Higgs-doublet model
• Probing the scalar sector in e^ + e^ - → f fH
• Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC
• Evidence for the spin-0 nature of the Higgs boson using ATLAS data
• τ polarimetry with multimeson states
• Higgs bosons: Intermediate mass range ate+e−colliders
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

Cited by

• Production of heavy Higgs bosons and decay into top quarks at the LHC. II. Top-quark polarization and spin correlation effects