Top Effective Operators at the ILC

Miguel C N Fiolhais

doi:10.1088/1742-6596/447/1/012032

Abstract

In this paper we study the effect of new physics contributions to the top quark pair production (tt̄) in a possible future linear collider, such as the International Linear Collider (ILC). The use of a dimension-six gauge invariant effective operator approach allows to compare the prospected results at the ILC with the current ones obtained at the Large Hadron Collider (LHC), both in neutral and charged current processes. We also prove that the use of specific observables, together with a combination of measurements in different polarized beam scenarios and with different center-of-mass energies, allows to disentangle different effective operator contributions and significantly improve the limits on the anomalous couplings with respect to the LHC.

Highlights

ILC versus LHC sensitivityThere are two effective operators involved in the Ztt vertex which have already been probed at the LHC: Oφ(3q,3+3) and Ou33W
In this paper we study the effect of top trilinear effective operators in e+e− → ttat the ILC
We find that the sensitivity to these operators largely surpasses the one achievable by the LHC either in neutral or charged current processes, allowing to probe new physics scales up to 4.5 TeV for a centre of mass energy of 500 GeV

Summary

ILC versus LHC sensitivity

There are two effective operators involved in the Ztt vertex which have already been probed at the LHC: Oφ(3q,3+3) and Ou33W. The variation of the unpolarised cross section and FB asymmetry at ILC f√or Cφ(3q,3+3) ranging in this interval is presented in figure 1. In figure 2 we plot the variation of the unpolarised cross section and FB asymmetry at sensitivity mainly. For of its this operator, the excellent contribution to e+e− → ttwith respect to W helicity observables [20]. The anti-Hermitian part of this operator can be probed with a CP-violating asymmetry ANFB defined for polarised top decays [21], being the estimated sensitivity. Potential LHC limits on Cu3B3 φ are relevant but would be surpassed at the ILC, as it can be seen in figure 4

Disentangling operator contributions

Findings

Summary