<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>P</mml:mi></mml:mrow></mml:math>-even,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:mrow></mml:math>-violating signals in scalar-mediated processes
Howard E. Haber, Venus Keus, Rui Santos
Abstract
Most studies of Higgs sector $CP$ violation focus on the detection of $CP$-violating neutral Higgs-fermion Yukawa couplings, which yield $P$-odd, $CP$-violating phenomena. There is some literature on purely bosonic signatures of Higgs sector $CP$ violation, where the simultaneous observation of three processes (suitably chosen) constitutes a signal of $P$-even $CP$ violation. However, in the examples previously analyzed, some of the processes are strongly suppressed in the approximate Higgs alignment limit (corresponding to the existence of a Standard Model-like Higgs boson as suggested by LHC data), in which case the proposed $CP$-violating signals are difficult to observe in practice. In this paper, we extend the existing literature by examining processes that do not vanish in the Higgs alignment limit and whose simultaneous observation would provide unambiguous evidence for scalar-mediated $P$-even $CP$ violation. We assess the discovery potential of such signals at various future multi-TeV lepton (and $\ensuremath{\gamma}\ensuremath{\gamma}$) colliders. The potential for detecting loop-induced $P$-even, $CP$-violating phenomena is also considered.