Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 8: Suche nach Supersymmetrie 1

T 8.9: Talk

Monday, March 27, 2017, 18:45–19:00, JUR 498

Background estimation for the 1-lepton stop search with ATLAS — •Paola Arrubarrena, David Handl, Jeannine Wagner-Kuhr, and Jovan Mitrevski — LMU, Munich, Germany

Supersymmetry (SUSY) is an extension of the standard model of particle physics which predicts a supersymmetric partner for each particle in the standard model. If R-parity is conserved, then the lightest supersummetric particle (LSP) is stable and a good dark matter candidate. In many models the LSP is favored to be the lightest neutralino (χ₁⁰), and the SUSY partner of the top quark, stop (t₁), is usually assumed to be light and in the reach of the LHC. In this talk a search for stop pair production with m_t − m_χ1⁰ < m_t is presented. Here both t₁ undergo a three-body decay to a bottom quark, a W boson and the LSP. Final states with one isolated electron or muon, missing transverse energy (MET) and several jets are considered.

The dominant background arises from top quark (tt) pair production, which is difficult to model in the extreme kinematic phase space of SUSY events, characterized by large MET and large transverse mass of the two W bosons (m_T). In this talk the strategy to determine the normalization of the backgrounds (e.g. tt, single top, W+jets, ttZ) in a data-driven way, using control regions, is described with emphasis on the different tt decay channels.