Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Physics

Content Description

1 online resource (xviii, 195 pages) : illustrations (some color)

Dissertation/Thesis Chair

Muhammad Sajjad Alam

Committee Members

Oleg Lunin, Muhammad Saleem, Dick Greenwood, Carolyn MacDonald


Experimental High Energy Physics, Quarks, Particles (Nuclear physics), Hadron interactions

Subject Categories



Large Hadron Collider (LHC) is a top quark factory, which is the heaviest elementary particle discovered so far. Due to its small life-time top quark decays before hadronization, and hence most of its properties are not washed out. Top quark events are often a large background in many beyond the Standard Model scenarios. For this reason, a deep knowledge of its properties and behavior is of crucial importance in searches for new physics at the LHC. This dissertation describes a measurement of the top anti-top pair production cross-section in &tau + jets channel. The measurement is obtained by using 4.7 fb -1 data collected in year 2011 by ATLAS detector from proton proton collisions at the center of mass energy (s) ½ = 7 TeV. Selected events are required to have one isolated &tau with missing transverse energy and hadronic jets, at least one of which must be originated from a b quark. The measured cross section is 152 ± 12 (stat.) ± 28 (syst.); ± 3(lumi.) pb, which is in agreement with standard model predictions.

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