Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 49: Higgs-Boson 4 (Zerfälle in Fermionen)

T 49.8: Talk

Tuesday, March 28, 2017, 18:30–18:45, JUR 3

Measurement of quark and gluon fake rates for hadronically decaying tau leptons with the ATLAS experiment — •Timo Dreyer, Stan Lai, and Michel Janus — II. Physikalisches Institut, Georg-August-Universität Göttingen

The tau lepton is the heaviest lepton in the Standard Model and therefore an important probe for physics at high energy scales. Due to its high mass, it has a strong coupling to the Higgs boson, which makes the decay mode H→ τ τ one of the best candidates for the measurement of the Higgs boson coupling to fermions.

For all signatures involving hadronically decaying tau leptons, it is important to have a good understanding of the tau reconstruction and identification algorithms that are used for data analysis in the ATLAS experiment. In particular, the probability for jets originating from quarks and gluons to be misidentified as hadronically decaying tau leptons (the so-called fake rate), is important for background estimation from a variety of sources. This fake rate depends on kinematic variables, as well as the quark-gluon composition of the process in question.

This talk presents an approach to measure the fake rate using the tag-and-probe technique in two kinematic regions in 13 TeV ATLAS data. In addition, a template fit is used to determine the fraction of quark- and gluon-initiated jets in the regions. These two measurements are combined in an attempt to extract pure quark and gluon fake rates.