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T: Fachverband Teilchenphysik

T 33: Search for new particles II

T 33.4: Vortrag

Dienstag, 31. März 2020, 17:45–18:00, H-HS XVI

Search for pair-produced leptoquarks decaying into quarks of the third and leptons of the first or second generation with the ATLAS experiment at √s=13 TeV — •Volker Austrup and Frank Ellinghaus — Bergische Universität Wuppertal

Motivated by similarities between the quark and lepton sectors in the Standard Model, leptoquarks (LQs) are hypothetical bosons that are assumed to couple to quarks and leptons at the same time. First proposed in the 1980s, the initial model includes couplings only within one generation. However, hints at flavor anomalies recently observed by various experiments such as LHCb, BaBar, and Belle have sparked interest in extended models with LQs coupling to quarks and leptons of different generations.
In this talk, a search for up- (q=2/3 e) and down-type (q=−1/3 e) LQs decaying into quarks of the third and leptons of the first or second generation is presented. The focus of this analysis is on final states with exactly one lepton and large amounts of missing transverse energy. Neural networks (NNs) are applied to ensure good separation between signal and background processes over a wide range of the parameter space. The NN output is subsequently used as the discriminating variable in a profile-likelihood fit in control and signal regions. Expected upper limits on the signal mass are obtained from the fit results as a function of the LQ branching ratio into charged and uncharged leptons. The analysis shown is based on pp-collision data at a centre-of-mass energy of √s=13 TeV measured by the ATLAS experiment at the LHC between 2015 and 2018.