Electroweak non-resonant corrections to top pair production close to threshold

TL;DR

This paper calculates the electroweak non-resonant NLO corrections to top pair production near threshold in e+ e- collisions, essential for precision measurements at future linear colliders.

Contribution

It provides the first detailed computation of NLO electroweak non-resonant corrections to e+ e- -> W+ W- b bbar near the top threshold, complementing existing QCD results.

Findings

NLO electroweak corrections are significant and necessary for precision.

Implementation of invariant mass cuts affects the cross section analysis.

Results improve theoretical accuracy for future collider experiments.

Abstract

The production of W+ W- b bbar from e+ e- collisions at energies close to the t tbar threshold is dominated by the resonant process with a nearly on-shell t tbar intermediate state. The W b pairs in the final state can also be reached through the decay of off-shell tops or through background processes containing no or only single top quarks. This non-resonant production starts to contribute at NLO to the W+ W- b bbar total cross section in the non-relativistic power-counting v ~ alpha_s ~ sqrt(alpha_EW). The NLO non-resonant corrections presented in this talk represent the non-trivial NLO electroweak corrections to the e+ e- -> W+ W- b bbar cross section in the top anti-top resonance region. In contrast to the QCD corrections which have been calculated (almost) up to NNNLO, the parametrically larger NLO electroweak contributions have not been completely known so far, but are mandatory for the required accuracy at a future linear collider. We consider the total cross section of the e+ e- -> W+ W- b bbar process and additionally implement cuts on the invariant masses of the W+ b and W- bbar pairs.