Analyzing $t\bar{t}Z$-couplings at the future $e^{-}p$ collider

Abstract

The proposed Large Hadron Electron Collider (LHeC), with center-of-mass energy of $\sqrt{s}\approx 1.3$ TeV, provides a clean and sensitive environment to probe the top quark's neutral current interactions with the $Z$ boson via the process $e^{-}p\to e^{-}t\bar{t}$. We investigate the precision with which the Standard Model (SM) $t\bar{t}Z$ couplings-the vector and axial-vector components ($\Delta C_{1V}$, $\Delta C_{1A}$)-can be measured, along with possible new physics effects parameterized by higher-dimensional operators inducing weak electric and magnetic dipole-like interactions ($C_{2V}$, $C_{2A}$). Focusing on the semileptonic decay channel, where either the top quark or anti-top decays leptonically to a positively charged lepton (${\ell }^{+}=e^{+},{\mu }^{+}$), we utilize the azimuthal angle difference $\Delta \varphi$ between the scattered electron and the charged lepton as the key observable. Using a one-parameter multi-bin ${\chi }^2$-analysis of this differential distribution, we find that constraints on $\Delta C_{1V}$ and $\Delta C_{1A}$ improve from order $10^{-1}$ at 50 fb${}^{-1}$ to order $10^{-2}$ at 1000 fb${}^{-1}$, corresponding to approximately 50% and 6% precision relative to their SM values. The anomalous tensor couplings $C_{2V}$ and $C_{2A}$ are constrained at the $10^{-1}$ level even at low luminosity and improve moderately with high luminosity. While the two-parameter analysis broadens the allowed regions due to parameter correlations, it retains competitive sensitivity, particularly for SM-like couplings. A systematic uncertainty of 5% is assumed throughout. These results highlight the LHeC's potential to provide complementary and competitive sensitivity to top-$Z$ couplings compared to current and future hadron and lepton collider capabilities.

13 pages, 4 Tables, 9 Captioned figures, Version accepted for publication in Physical Review D

References in corpus (37)

• FeynRules 2.0 - A complete toolbox for tree-level phenomenology
• MadGraph 5 : Going Beyond
• Dimension-Six Terms in the Standard Model Lagrangian
• A Large Hadron Electron Collider at CERN: Report on the Physics and Design Concepts for Machine and Detector
• Uncertainties of predictions from parton distribution functions II: the Hessian method
• A minimal set of top anomalous couplings
• GetDist: a Python package for analysing Monte Carlo samples
• Effective-Field-Theory Approach to Top-Quark Production and Decay
• Scalar and pseudoscalar Higgs production in association with a top-antitop pair
• Next-to-leading order QCD corrections to t-tbar-Z production at the LHC
• Constraining top quark effective theory in the LHC Run II era
• Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Single top production in association with a Z boson at the LHC
• Probing top-Z dipole moments at the LHC and ILC
• Measurement of top quark pair production in association with a Z boson in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Global and optimal probes for the top-quark effective field theory at future lepton colliders
• Constraining couplings of the top quarks to the Z boson in ttbar+Z production at the LHC
• Azimuthal Angle Probe of Anomalous HWW Couplings at the LHeC
• Top effective operators at the ILC
• Probing anomalous couplings using di-Higgs production in electron-proton collisions
• Probing $tt\gamma$ and $ttZ$ couplings at the LHeC
• Determining $V_{tb}$ at Electron-Positron Colliders
• Probing $Zt\bar{t}$ couplings using $Z$ boson polarization in $ZZ$ production at hadron colliders
• Unravelling the anomalous gauge boson couplings in $Z{W}^{\pm }$ production at the LHC and the role of spin-$1$ polarizations
• Measuring CP nature of top-Higgs couplings at the future Large Hadron electron collider
• Inclusive and differential cross section measurements of single top quark production in association with a Z boson in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Inclusive and differential cross-section measurements of $t\bar{t}Z$ production in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector, including EFT and spin-correlation interpretations
• Fingerprinting the Top quark FCNC via anomalous $Ztq$ couplings at the LHeC
• Boosting New Physics Searches in $t\bar{t}Z$ and $tZj$ Production with Angular Moments
• An Experiment for Electron-Hadron Scattering at the LHC
• On two-body and three-body spin correlations in leptonic $t\bar{t}Z$ production and anomalous couplings at the LHC
• Measurements of inclusive and differential cross sections for top quark production in association with a Z boson in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Axion-Like Particles at future $e^{-}p$ collider
• Search for new physics using effective field theory in 13 TeV pp collision events that contain a top quark pair and a boosted Z or Higgs boson
• Exploring CP-even scalars of a Two Higgs-doublet model in future $e^{-}p$ colliders
• Asymmetry Observables for Measuring Spin Correlations in Top-Quark Pair Production
• Top quark effective couplings from top-pair tagged photoproduction in $p{e}^{-}$ collisions