Search for the Higgs
Task 2

Among other things, the LHC was built to find evidence of the Higgs field in our universe by discovering the Higgs particle for which physicists have been searching for a while. Theoretical predictions tell us that heavy particles, e.g. top quarks, produced in collisions within the LHC might produce such Higgs particles. The LHC experiments ATLAS and CMS have seen first signs of this particle. The dataset you will analyse contains events with two WW particles. Pick them out and measure the angle between the two leptons (that arise from the W’s) in the transverse plane, ΔΦll. Fill your tally sheet and write down the angle.



Several criteria determine whether an event is a WW candidate. These events have to:

  • contain exactly two electrically charged leptons, the charges have to be opposite and the isolation value has to be less than 0.2
  • contain a leading lepton (the one with higher transverse momentum) with a transverse momentum of at least 20 GeV and a sub-leading lepton (the one with lower transverse momentum) with at least 10 GeV. Furthermore
  • have missing transverse momentum (depending on the kind of leptons involved)
    • of at least 40 GeV if both leptons are coming from the same family
    • of at least 20 GeV in the other case.


Only if an event fulfills all these criteria it can be called a WW candidate event.