CP-violating top quark couplings at future linear $e^+e^-$ colliders

W. Bernreuther , L. Chen , I. García , M. Perelló , R. Poeschl (1) , F. Richard (1) , E. Ros , M. Vos

1 LAL - Laboratoire de l'Accélérateur Linéaire

We study the potential of future lepton colliders to probe violation of the CP symmetry in the top quark sector. In certain extensions of the Standard Model, such as the two-Higgs-doublet model (2HDM), sizeable anomalous top quark dipole moments can arise, which may be revealed by a precise measurement of top quark pair production. We present results from detailed Monte Carlo studies for the ILC at $500 \hbox { GeV}$ and CLIC at $380 \hbox { GeV}$ and use parton-level simulations to explore the potential of high-energy operation. We find that precise measurements in $e^+e^- \rightarrow t\bar{t}$ production with subsequent decay to lepton plus jets final states can provide sufficient sensitivity to detect Higgs-boson-induced CP violation in a viable two-Higgs-doublet model. The potential of a linear $e^+e^-$ collider to detect CP-violating electric and weak dipole form factors of the top quark exceeds the prospects of the HL-LHC by over an order of magnitude.

Mots clés: electron positron: annihilation; electron positron: colliding beams; CP: violation; top: pair production; top: form factor; top: coupling; coupling: anomaly; form factor: dipole; jet: final state; symmetry: CP; Higgs particle: doublet; CERN LHC Coll: upgrade; final state: ((n)jet lepton); sensitivity; numerical calculations: Monte Carlo; CERN CLIC; ILC Coll; proposed experiment

Domaines: Physique des Hautes Energies - Expérience [hep-ex]; Physique des Hautes Energies - Phénoménologie [hep-ph]

W. Bernreuther, L. Chen, I. García, M. Perelló, R. Poeschl, et al.. CP-violating top quark couplings at future linear $e^+e^-$ colliders. European Physical Journal C: Particles and Fields, 2018, 78 (2), pp.155. ⟨10.1140/epjc/s10052-018-5625-3⟩. ⟨hal-01719871⟩