Top quark physics

Since the start of LHC data taking, the CMG group has made pivotal contributions to the CMS top physics programme, with a focus on top mass measurements, b content and particle based properties of top pair events, and searches for top quark production in exotic production modes including photon-photon, pPb and PbPb collisions:

Candidate ttbar event in Heavy Ion collisions
Candidate ttbar event in heavy-ion collisions (CERN news, PRL)

Ongoing analysis projects are listed below. This is a dynamic and non-exhaustive list. Feel free to get in touch with any of us if you are interested to learn more. More help and new ideas are always welcome!

  • WbWb scattering: (full Run 2)
    A novel method for a model-independent measurement of the top quark decay width using the single top off-shell / on-shell scattering asymmetry double ratio
    • CMG people involved: Matthias, Matteo, Martijn, Michael, Jan, Pedro
    • in collaboration with KIT
  • Measurement of colour flow in top pair events (2016 data)
    The first CMS measurement of colour flow using the pull-angle variable, and the first at LHC to introduce an adapted version of the LEP colour flow observables
    • CMG people involved: Pedro, Martijn
    • in collaboration with Viesturs Veckalns (RTU) and Markus Seidel (Maryland)
  • Search for exclusive top quark production with CT-PPS (2017 data) [TOP-21-007]
    The first search for exclusive production of top quarks with tagged protons, using the CT-PPS detector
    • CMG people involved: Michael, Martijn, Pedro
    • in collaboration with Genova, Torino, Kansas, LIP, DESY
  • Search for diffractive top quark production with CT-PPS (2017 low-mu data)
    Aiming for the first observation of single diffractive production of top quarks with tagged protons, using the CT-PPS detector
    • CMG people involved: Michael, Martijn, Pedro, David
  • LHC and World combination of top quark mass measurements (Run 1)
    Delivering the world’s most precise measurement of the top quark mass based on the legacy LHC Run1 (and Tevatron) results
    • CMG people involved: Matteo, Martijn
    • with the LHC Top WG, Mark Owen (Glasgow) and Steve Wimpenny (UCR)
  • Top anti-top mass difference measurement (full Run 2)
    Improving on CMS’ world-record measurement of a potential difference between the top quark and top anti-quark mass
    • CMG people involved: Martijn, Pedro
    • in collaboration with Andris Potrebko (RTU) and Markus Seidel (Maryland)