Abstract
Constraining CP-violating interactions in effective field theory (EFT) of dimension six faces two challenges. Firstly, degeneracies in the multi-dimensional space of Wilson coefficients have to be lifted. Secondly, quadratic contributions of CP-odd dimension six operators are difficult to disentangle from squared contributions of CP-even dimension six operators and from linear contributions of dimension eight operators. Both of these problems are present when new sources of CP-violation are present in the interactions between the Higgs boson and heavy strongly-interacting fermions. We show that degeneracies in the Wilson coefficients can be removed by combining measurements of Higgs-plus-two-jet production via gluon fusion with measurements of top-pair associated Higgs production. In addition, we demonstrate that the sensitivity of the analysis can be improved by exploiting the top-quark threshold in the gluon fusion process. Finally, we substantiate a perturbative argument about the validity of EFT by comparing the quadratic and linear contributions from CP-odd dimension six operators and use this to show explicitly that high statistics measurements at future colliders enable the extraction of perturbatively robust constraints on the associated Wilson coefficients.
Highlights
The search for new physics beyond the Standard Model (SM) is a central task of the Large Hadron Collider (LHC)
We show that degeneracies in the Wilson coefficients can be removed by combining measurements of Higgs-plus-two-jet production via gluon fusion with measurements of top-pair associated Higgs production
We substantiate a perturbative argument about the validity of effective field theory by comparing the quadratic and linear contributions from CP-odd dimension-six operators and use this to show explicitly that high statistics measurements at future colliders enable the extraction of perturbatively robust constraints on the associated Wilson coefficients
Summary
The search for new physics beyond the Standard Model (SM) is a central task of the Large Hadron Collider (LHC). In the case of the CP-odd operators of Eq (1), momentum transfer-dependent differential distributions used for the CP-even operators are identically zero for the new physics contribution This makes the extraction of the CP-violating effects in the fermion-Higgs interactions and their separation from competing modifications of the gauge sectorHiggs interactions much more complicated to order ∼ct, cg. Under the assumption that the Higgs couples to electrons with SM strength the most stringent constraints are obtained from measurements of the electron’s electric dipole moment [49], ct ∼ Oð10−3Þ In this analysis we focus on limits that can be obtained in direct measurements at the LHC and future colliders while investigating the interplay between Og and Ot as well as the perturbative behavior of such limits.
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