LHC Higgs Working Group WG3 (BSM) -- Extended Higgs Sector subgroup meeting

Friday 6 Nov 2026, 14:00 → 18:00 Europe/Zurich

Alexandra Carvalho Antunes De Oliveira (Peking University (CN)), Khawla Jaffel (National Institute of Chemical Physics and Biophysics (EE)), Lidija Zivkovic (Institute of physics Belgrade (RS)), Nikolaos Rompotis (University of Liverpool (UK)), THOMAS Biekötter (IFT Madrid), Tania Robens (IRB Zagreb)

14:00 → 14:20 CP violation in charged Higgs decay

We investigate CP violation in the process H±→W±Z within the framework of the two-Higgs-Doublet model (2HDM). Amplitudes are expressed transparently in terms of physical couplings. Our analysis qualitatively confirms recent results by Kanemura and Mura, for the interference between one-loop bosonic and fermionic amplitudes. Furthermore, we identify additional sources of CP violation arising from internal interference among the bosonic and also among the fermionic loop amplitudes. In the alignment limit, the asymmetry would vanish in the absence of fermionic loop contributions when the sum of the masses of the additional neutral scalars is higher than the mass of the Z. Our results allow for generic Yukawa couplings, and cover both explicit and spontaneous CP violation. For inclusive W± and Z decays, the CP violation will only manifest itself as a charge asymmetry.

Speaker: Per Osland (University of Bergen (NO))

14:30 → 14:50 CPV in hh and Zh decays

We present an LHC probe of CP violation (CPV) within a BSM scalar sector by simultaneously searching for hh and Zh decays of a BSM Higgs boson. We investigate the sensitivity of this probe for HL-LHC in the context of a concrete model, the C2HDM, and discuss its complementarity with existing searches for CPV in the Higgs sector (e.g. via CP measurements of 125 GeV Higgs couplings to tau leptons and top quarks).

Speaker: Jose Miguel No (IFT-UAM/CSIC)

15:00 → 15:20 Top-Quark Pair Production and Decay in 2HDM

The process of top-quark pair production through the decay of the scalars and the pseudoscalar in the 2-Higgs-doublet extension of the Standard Model is associated with large interference effects between the loop-induced Higgs signal, and the QCD continuum background. We present a modified version of the hvq library of POWHEG-BOX-V2 event generator with the OpenLoops 2 amplitude generator to attach leptonic decays with full spin correlation effects to the top-quark pair production process at NLO+PS. We perform analyses of differential cross sections as functions of spin-sensitive observables to study the significance of the results in searches for new scalars and pseudoscalars beyond the Standard Model at the LHC.

Speaker: Vishakha Lingadahally