Lorentz and $\text{CPT}$ violation in top-quark production and decay

Abstract

The prospects are explored for testing Lorentz and $\text{CPT}$ symmetry in the top-quark sector. We present the relevant Lagrange density, discuss physical observables, and describe the signals to be sought in experiments. For top-antitop pair production via quark or gluon fusion with subsequent semileptonic or hadronic decays, we obtain the matrix element in the presence of Lorentz violation using the narrow-width approximation. The issue of testing $\text{CPT}$ symmetry in the top-quark sector is also addressed. We demonstrate that single-top production and decay is well suited to a search for $\text{CPT}$ violation, and we present the matrix elements for single-top production in each of the four tree-level channels. Our results are applicable to searches for Lorentz violation and studies of $\text{CPT}$ symmetry in collider experiments, including notably high-statistics top-antitop and single-top production at the Large Hadron Collider.