SUSY searches at CMS and ATLAS at LHC are actively ongoing. SUSY particles in R-parity conserved models are usually searched for in events with large missing transverse momentum (MET). QCD events with large MET are rare events. However, because of the large cross section of QCD events, unless they are significantly reduced, QCD background events overwhelm the SUSY signal in the event sample. In searches in all-hadronic final states in CMS and ATLAS, the azimuthal angle between a jet and MET (or MHT) is widely used to reduce QCD background events with large MET, which is caused by a jet pT mismeasurement or neutrinos from semileptonically decaying hadrons in a jet. Another azimuthal angle, the angle between a jet pT and MHT defined with the other jets in the event, is also used to reduce QCD background events in CMS. We have carefully reviewed geometric and analytic properties of these angles and identified room for improvement. We have subsequently developed alternative angular variables which can perform better in rejecting QCD background events in SUSY searches at LHC. In this talk, we will show the definition and physics motivation of the alternative angular variables and demonstrate their performance in Monte-Carlo event samples simulated in DELPHES.
|Publication status||Unpublished - 14 Dec 2017|
|Event||25th INTERNATIONAL CONFERENCE ON SUPERSYMMETRY AND THE UNIFICATION OF FUNDAMENTAL INTERACTIONS - Tata Institute of Fundamental Research, Mumbai, India|
Duration: 11 Dec 2017 → 15 Dec 2017
|Conference||25th INTERNATIONAL CONFERENCE ON SUPERSYMMETRY AND THE UNIFICATION OF FUNDAMENTAL INTERACTIONS|
|Period||11/12/17 → 15/12/17|
Sakuma, T., Flächer, H., & Smith, D. (2017). Alternative angular variables for QCD multijet background event suppression in SUSY searches at the LHC. Abstract from 25th INTERNATIONAL CONFERENCE ON SUPERSYMMETRY AND THE UNIFICATION OF FUNDAMENTAL INTERACTIONS, Mumbai, India.