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

We evaluate the implications of LHC and LEP/SLC measurements for the electro-weak couplings of the top and bottom quarks. We derive global bounds on the Wilson coefficients of ten two-fermion operators in an effective field theory description. The combination of hadron collider data with Z-pole measurements is found to yield tight limits on the operator coefficients that modify the left-handed couplings of the bottom and top quark to the Z boson. We also present projections for the high-luminosity phase of the LHC and for future electron-positron colliders. The bounds on the operator coefficients are expected to improve substantially during the remaining LHC programme, by factors of 1 to 5 if systematic uncertainties are scaled as statistical ones. The operation of an e + e − collider at a center-of-mass energy above the top-quark pair production threshold is expected to further improve the bounds by one to two orders of magnitude. The combination of measurements in pp and e + e − collisions allows for a percent-level determination of the top-quark Yukawa coupling, that is robust in a global fit.

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“…The legacy result of LHC Run 1 is κ t = 1.40 +0. 24 −0.21 [78]. Significantly sharper results are available from Run 2 measurements [79,80].…”

Section: Indirect and Direct Boundsmentioning

confidence: 99%

The electro-weak couplings of the top and bottom quarks — Global fit and future prospects

Durieux¹,

Quiles²,

Miralles³

et al. 2019

J. High Energ. Phys.

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“…Systematic uncertainties have been evaluated to some extent in Refs. [1,47]. It is plausible that theoretical and experimental systematics can be controlled to the level of the statistical uncertainties assumed here.…”

Section: Clic-like Scenariomentioning

confidence: 84%

“…For estimating measurement uncertainties, we rely on the available full-simulation studies performed by the ILC and CLIC collaborations for the lepton-plus-jets final state obtained after one hadronic and one semi-leptonic top-quark decay [1,19,47]. The charged lepton is taken to be either an electron or a muon.…”

Section: Clic-like Scenariomentioning

confidence: 99%

Global and optimal probes for the top-quark effective field theory at future lepton colliders

Durieux

Perelló

Vos

et al. 2018

J. High Energ. Phys.

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We study the sensitivity to physics beyond the standard model of precise top-quark pair production measurements at future lepton colliders. A global effectivefield-theory approach is employed, including all dimension-six operators of the Warsaw basis which involve a top-quark and give rise to tree-level amplitudes that interfere with standardmodel e + e − → tt → bW +b W − ones in the limit of vanishing b-quark mass. Four-fermion and CP-violating contributions are taken into account. Circular-collider-, ILC-and CLIClike benchmark run scenarios are examined. We compare the constraining power of various observables to a set of statistically optimal ones which maximally exploit the information contained in the fully differential bW +b W − distribution. The enhanced sensitivity gained on the linear contributions of dimension-six operators leads to bounds that are insensitive to quadratic ones. Even with statistically optimal observables, two centre-of-mass energies are required for constraining simultaneously two-and four-fermion operators. The impact of the centre-of-mass energy lever arm is discussed, that of beam polarization as well. A realistic estimate of the precision that can be achieved in ILC-and CLIC-like operating scenarios yields individual limits on the electroweak couplings of the top quark that are one to three orders of magnitude better than constraints set with Tevatron and LHC run I data, and three to two hundred times better than the most optimistic projections made for the high-luminosity phase of the LHC. Clean global constraints can moreover be obtained at lepton colliders, robustly covering the multidimensional effective-field-theory space with minimal model dependence.

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“…Similar considerations hold for CP-violating EFT operators that could be efficiently probed by specifically designed CP-odd observables[119].…”

mentioning

confidence: 78%

Top-quark physics at the CLIC electron-positron linear collider

Abramowicz

Tehrani

Arominski

et al. 2019

J. High Energ. Phys.

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141

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

Cited by 23 publications

References 71 publications

The electro-weak couplings of the top and bottom quarks — Global fit and future prospects

The electro-weak couplings of the top and bottom quarks — Global fit and future prospects

Global and optimal probes for the top-quark effective field theory at future lepton colliders

Top-quark physics at the CLIC electron-positron linear collider

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