Eur. Phys. J. C (2018) 78: 155
https://doi.org/10.1140/epjc/s10052-018-5625-3

Special Article - Tools for Experiment and Theory

CP-violating top quark couplings at future linear colliders

¹ Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University, 52056, Aachen, Germany
² Instituto de Física Corpuscular (IFIC, UVEG/CSIC), Apartado de Correos 22085, 46071, Valencia, Spain
³ Laboratoire de l’Accélérateur Linéaire (LAL), Centre Scientifique d’Orsay, 91898, Orsay Cedex, France
⁴ Max-Planck-Institut f. Physik, 80805, Munich, Germany
⁵ CERN, 1211, Geneva 23, Switzerland

^* e-mail: ignacio.garcia@ific.uv.es

Received: 24 October 2017
Accepted: 9 February 2018
Published online: 23 February 2018

Abstract

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 and CLIC at and use parton-level simulations to explore the potential of high-energy operation. We find that precise measurements in 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 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.