Spin correlations in $t\bar{t}$ production

by James William Howarth (University of Glasgow (GB)), Rene Poncelet (Cambridge University)

Thursday 21 Jul 2022, 11:00 → 12:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The study of top-quark pairs is one of the standard candle measurements at the LHC which is carried out with increasing precision. Due to the short top-quark lifetime, it is possible to access the spin correlations of the top quark pairs through kinematic properties of reconstructed decay products. In recent years, both experimental measurements and fixed-order calculations of spin correlations in these processes have reached impressive predictions and revealed interesting tensions.

 

Experimental results use ever-more sophisticated techniques to measure these effects and correct them for detector acceptance and smearing. Dr Howarth will present results on spin correlation from the ATLAS experiment, discuss their agreement with equivalent CMS results, and provide motivation for future collider measurements.

 

Theoretical descriptions of spin correlations are vital tools in stress testing the Standard Model and searching for peculiar effects of new physics. To do so with precision and accuracy, higher order QCD predictions are not negligible and have profound impact on differential distributions which are necessary to describe recent precision measurements. Dr Poncelet will present the state-of-the-art calculations used to describe experimental data, discuss their agreement and the puzzling tension between predictions of fiducial result and full-phase space calculations with data.

 

James -- Bio

• PhD at the University of Manchester. Thesis on Observation of spin correlations in ttbar events
• DESY fellow working mostly on top cross-section measurements and Monte Carlo development
• Postdoc at the university of Manchester working on ttH and top properties, including spin correlation
• Royal Society University Research Fellow at the University of Glasgow
• Roles on ATLAS:
  • Top cross-section convener
  • Top properties convener 
• Current research interests:
  • Using top and Higgs physics as a quantum information laboratory
  • Early Run3 top cross-section measurements
  • Elastic top production

René -- Bio

• 2010-2015 Bachelor/Master in Physics, Georg-August University Göttingen
• 2015-2018 PhD in Physics, RWTH Aachen University
• Since 2018 Research Associate at the Cavendish Laboratory Cambridge
• Since 2021 Leverhulme and Newton Trust Early Career Fellow at the Cavendish Laboratory Cambridge
• Since 2021 College Research Associate Emmanuel College Cambridge