Rencontres de Moriond QCD 2012: Straight to the Top

Friday’s sessions took a trip into the domain of the Top quark, which was discovered at Fermilab back in early March 1995 and was reported two weeks later at Moriond. The LHC and Tevatron experiments presented the latest measurements of the production of the top quark and its decays. An understanding of the top quark is vital for the verification of the Standard Model as well as a potential window for new physics beyond the Standard Model.


Measurements of the top mass by LHC and Tevatron.

Top quark events are background for Higgs searches and hence need to be well understood. Moreover, since it is the heaviest known elementary particle, finding its mass to great precision will help validate the Standard Model Higgs (if it exists). “We want to measure as many of its properties as possible, as precisely as possible,” says Alison Lister, from University of Geneva, who presented some of the LHC experiments’ results at the conference.

The LHC experiments presented a variety of new results, furthering the understanding of the top in various areas. Among them was a new measurement by ATLAS of the mass of the top quark using events with a single lepton. CMS presented the most precise measurement of the mass of the top quark by any LHC experiment to-date, using events with a single muon. CMS also studied a potential mass difference between the top quark and antiquark, looking for signs of CPT violation. They found a discrepancy still dominated by uncertainty, but expect to reduce these error margins by examining their complete, large dataset recorded so far.

The Tevatron experiments presented world-leading results utilising the full Tevatron dataset, including the world’s most precise measurement of the mass of the top quark. The top quark will always be a legacy of the Tevatron experiments, which will continue to provide a substantial contribution to the world average for years to come.


You can read more reports from Moriond QCD and EW 2012 here, and you can access all the Moriond QCD presentations here.

by Katarina Anthony