NLO and NNLO corrections to polarized top quark decays

Stefan Groote,Jürgen G Körner

doi:10.1051/epjconf/201819200006

Abstract

We present partial results on NLO and NNLO QCD, and NLO electroweak corrections to polarized top quark decays. In parallel we derive positivity bounds for the polarized structure functions in polarized top quark decays and check them against the perturbative corrections to the structure functions.

Highlights

In the limited space available to us in this write-up of a talk given at the International Workshop on QCD Theory and Experiment (QCD@Work 2018) in Matera, Italy, we cannot review the subject of polarized top quark decays in any depth
Instead we take the opportunity to report on results on radiative corrections to polarized top quark decays obtained by our group in the last few years
The dominant source of polarized top quarks is from weak t–channel production with an average polarization of ≈ 90 % for the produced top quarks

Summary

Introduction

In the limited space available to us in this write-up of a talk given at the International Workshop on QCD Theory and Experiment (QCD@Work 2018) in Matera, Italy, we cannot review the subject of polarized top quark decays in any depth. Instead we take the opportunity to report on results on radiative corrections to polarized top quark decays obtained by our group in the last few years. We take the opportunity to specify which perturbative calculations have been done and which remain to be done. The motivation for studying polarized top quark decays is provided by the huge sample of singly produced polarized top quarks at the LHC. The projected overall luminosity of the future high luminosity HL-LHC is 3 ab−1 which corresponds to ∼ 109 singly produced top quarks. Top quarks retain their polarization at birth when they decay since the life time of the top quark is so short. The full angular decay distribution for polarized top quark decay t(↑) → Xb + l+ + νl in the top quark rest frame can be written in terms of the four structure functions A, B, C and D

D A sin φ

The LO angular distribution

The NLO angular distribution

NLO positivity bounds for the T –odd structure function D

NNLO QCD corrections to sequential polarized top quark decay