Modelling $Z\to \tau \tau$ processes in ATLAS with $\tau$-embedded $Z\to \mu \mu$ data

Abstract

This paper describes the concept, technical realisation and validation of a largely data-driven method to model events with $Z\to \tau \tau$ decays. In $Z\to \mu \mu$ events selected from proton--proton collision data recorded at $\sqrt{s}=8$ TeV with the ATLAS experiment at the LHC in 2012, the $Z$ decay muons are replaced by $\tau$ leptons from simulated $Z\to \tau \tau$ decays at the level of reconstructed tracks and calorimeter cells. The $\tau$ lepton kinematics are derived from the kinematics of the original muons. Thus, only the well-understood decays of the $Z$ boson and $\tau$ leptons as well as the detector response to the $\tau$ decay products are obtained from simulation. All other aspects of the event, such as the $Z$ boson and jet kinematics as well as effects from multiple interactions, are given by the actual data. This so-called $\tau$-embedding method is particularly relevant for Higgs boson searches and analyses in $\tau \tau$ final states, where $Z\to \tau \tau$ decays constitute a large irreducible background that cannot be obtained directly from data control samples. In this paper, the relevant concepts are discussed based on the implementation used in the ATLAS Standard Model $H\to \tau \tau$ analysis of the full datataset recorded during 2011 and 2012.

24 pages plus author list + cover pages (41 pages total), 13 figures, 0 tables, submitted to JINST, All figures, including auxiliary figures, are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2014-09

References in corpus (10)

• Pileup subtraction using jet areas
• Measurement of the $Z/{\gamma }^{\ast }$ boson transverse momentum distribution in $pp$ collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector
• Jet energy measurement and its systematic uncertainty in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector
• Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton-proton collision data
• Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data
• Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector
• Search for charged Higgs bosons decaying via H+ -> tau nu in top quark pair events using pp collision data at sqrt(s) = 7 TeV with the ATLAS detector
• Search for neutral Higgs bosons of the minimal supersymmetric standard model in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector
• Identification and energy calibration of hadronically decaying tau leptons with the ATLAS experiment in $pp$ collisions at $\sqrt{s}$=8 TeV
• Search for charged Higgs bosons decaying via $H^{\pm }\to {\tau }^{\pm }\nu$ in fully hadronic final states using $pp$ collision data at $\sqrt{s}=8$ TeV with the ATLAS detector

Cited by in corpus (10)

• Measurements of the Higgs boson production and decay rates and coupling strengths using $pp$ collision data at $\sqrt{s}=7$ and $8$ TeV in the ATLAS experiment
• Searches for Higgs boson pair production in the $hh\to bb\tau \tau ,\gamma \gamma WW\ast ,\gamma \gamma bb,bbbb$ channels with the ATLAS detector
• Search for additional neutral MSSM Higgs bosons in the $\tau \tau$ final state in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for lepton-flavour-violating decays of the Higgs and $Z$ bosons with the ATLAS detector
• Cross-section measurements of the Higgs boson decaying into a pair of tau-leptons in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for lepton-flavour-violating $H\to \mu \tau$ decays of the Higgs boson with the ATLAS detector
• Search for new phenomena with top quark pairs in final states with one lepton, jets, and missing transverse momentum in $pp$ collisions at $\sqrt{s}$= 13 TeV with the ATLAS detector
• Measurements of Higgs boson production cross-sections in the $H\to {\tau }^{+}{\tau }^{-}$ decay channel in $pp$ collisions at $\sqrt{s}=13\text{TeV}$ with the ATLAS detector
• Measurement of the $\mathrm{Z}{\gamma }^{\ast }\to \tau \tau$ cross section in pp collisions at $\sqrt{s}=$ 13 TeV and validation of $\tau$ lepton analysis techniques
• Search for lepton-flavor-violating decays of the $Z$ boson into a $\tau$ lepton and a light lepton with the ATLAS detector