# Münster 2017 – wissenschaftliches Programm

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# T: Fachverband Teilchenphysik

## T 18: Top Quark (Theorie) 1

### T 18.2: Vortrag

### Montag, 27. März 2017, 17:00–17:15, VSH 05

**Polarised amplitudes for top quark pair production at NNLO** — •Rene Poncelet and Michal Czakon — RWTH Aachen University Institute for Theoretical Particle Physics and Cosmology, Aachen, Germany

More than 20 years after its discovery, the investigation of the top-quark
and its properties is in a high-precision phase. The LHC plays a central role
in this investigation since it provides a large number of *t*t-pairs.
Precise top-quark measurements
are an excellent tool for precision measurements of the Standard Model and
searches for new physics. An important ingredient for this kind of measurements are precise
theory predictions. Meanwhile, NNLO QCD predictions for *t*t-pair production at the LHC
became available for comparison to data. Inclusive or differential, these
predictions have in common that they assume stable top-quarks and
use spin-summed matrix-elements. The information about spin-correlations
with decay products is therefore lost. I present here the first calculation of amplitudes
for production of polarized on-shell *t*t-pairs at NNLO QCD which is a necessary
ingredient to incorporate spin-correlated top-decays in Narrow-Width-Approximation.
The full calculation
including higher order corrections to the decays
can be used to extract the top-quark mass parameter more precisely from the
examination of differential distributions of decay products.