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The ATLAS tau trigger and planned trigger efficiency studies with early data
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. (Experimental High Energy Physics)
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. (Experimental High Energy Physics)
University of Regina.
University of Regina.
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2009 (English)In: Proceedings of CHarged2008 / [ed] T. Ekelöf, J. Rathsman, Trieste: Proceedings of Science , 2009, 1-7 p.Conference paper, Published paper (Refereed)
Abstract [en]

The tau trigger system of the ATLAS detector has been developed to increase the sensitivity ofthe detector to the Higgs boson and searches for physics beyond the Standard Model.  A trigger system split in three levels has been designed for hadronically decaying tau leptons optimized for efficiency and good background rejection.  At the first level the trigger uses only information from the calorimeters while the other two levels include also information from the tracking.  Both energy and shape variables for the hadronic tau jets are used in the trigger algorithms.  The very intense QCD background, however, makes it a challenge to develop an efficient trigger with high purity at low transverse momentum. Thus the tau trigger is best used in combination with other trigger variables such as missing transverse energy or jets.  Before the tau trigger can be used in searches, it has to be commissioned with data and the efficiency and background rejectionof QCD has to be studied in detail.

Place, publisher, year, edition, pages
Trieste: Proceedings of Science , 2009. 1-7 p.
Series
Proceedings of Science, ISSN 1824-8039
Keyword [en]
ATLAS, LHC, CERN, Trigger, Tau lepton
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
URN: urn:nbn:se:uu:diva-142227OAI: oai:DiVA.org:uu-142227DiVA: diva2:387153
Conference
Prospects for Charged Higgs Discovery at Colliders
Available from: 2011-01-13 Created: 2011-01-13 Last updated: 2011-03-11Bibliographically approved
In thesis
1. Measurements of Angular Correlations in Minimum Bias Events and Preparatory Studies for Charged Higgs Boson Searches at the Tevatron and the LHC
Open this publication in new window or tab >>Measurements of Angular Correlations in Minimum Bias Events and Preparatory Studies for Charged Higgs Boson Searches at the Tevatron and the LHC
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Studies of minimum bias events at colliders probe the behavior of QCD in the non-perturbative regime. The phenomenology of events in this regime is described by empirical models that take many parameters, which all need to be tuned to the observed data. Measurements based on angular correlations between the highest transverse momentum charged particle track and the other charged particle tracks in collision events can, because of their robustness against experimental and detector effects, be a component of the tuning inputs for the models. We measure such observables in a variety of pseudorapidity ranges and at many center-of-mass energies at DØ and ATLAS. We observe that such observables are poorly described by current models and tunes that are used to produce simulated event samples, making them valuable information for the tuning process.

The Matrix Element method is a powerful analysis tool to extract precise measurements from data samples of limited statistics. We have investigated the potential of the Matrix Element method to measure the mass of the charged Higgs in the exclusive decay H±→τ±ν→e±+3ν when produced in top quark decays at the Tevatron, with emphasis on the construction of transfer functions in the τ decay chain. We concluded that the τ decay chain can be successfully parametrized via a transfer function and that the method has the potential to provide an accurate charged Higgs mass measurement in this channel.

Triggering on τ leptons is a key component for many beyond the Standard Model searches at ATLAS, such as the search for the charged Higgs boson. Events containing Z bosons can be used to measure the efficiency of the ATLAS τ hadronic-decay trigger. We have used a tag-and-probe method on simulated Z boson decays to 2 τ leptons where one decays to a μ while the other decays hadronically. The μ is used as the tag and the τ side is probed. We demonstrated that the efficiency of the τ hadronic-decay trigger can be accurately measured with this method using the first 100 pb-1 of ATLAS data.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 50 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 802
Keyword
ATLAS, D0, LHC, Tevatron, CERN, Fermilab, QCD, Monte Carlo tunes, Matrix Element method, Charged Higgs boson, Tau lepton, Trigger
National Category
Physical Sciences Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-142464 (URN)978-91-554-7989-3 (ISBN)
Public defence
2011-03-04, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Note
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 732Available from: 2011-02-10 Created: 2011-01-14 Last updated: 2011-03-21Bibliographically approved

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