Results of numerical simulations for unstable-particles pair production in modified perturbation theory in NNLO

TL;DR

This paper demonstrates that modified perturbation theory (MPT) provides highly accurate NNLO calculations for unstable-particle pair production, showing excellent convergence and precision near and above cross-section peaks, especially relevant for ILC energies.

Contribution

It introduces and validates the use of MPT for NNLO calculations of unstable-particle pair production, achieving high precision and convergence.

Findings

Excellent convergence of MPT near cross-section maxima

Precision at the level of one per-mille for W-boson production at ILC energies

Validated MPT's effectiveness for top-quark and W-boson pair production

Abstract

We consider pair production and decay of fundamental unstable particles in the framework of a modified perturbation theory (MPT), which treats resonant contributions of unstable particles in the sense of distributions. The cross-sections for the top-quark pair production and for the $W$-boson pair production in $e^{+}e^{-}$ annihilation are calculated within the NNLO in models that admit exact solutions. In both cases an excellent convergence of the MPT is detected at the energies close to and above the maximum of the cross section. In the case of $W$-boson pair production a precision of the description at the ILC energies is ensured at the level of one per-mille or higher.