|Ph.D Student||Silvia Beha-Harpaz|
|Subject||Top Quark Mass Measurement via Leptons Correlation and|
Search for Charged Higgs Bosons in the Hadronic
Tau Final State
|Department||Department of Physics||Supervisor||Full Professor Rozen Yoram|
|Full Thesis text|
The ATLAS detector is intended to investigate many different types of physics that might become detectable in the energetic collisions at the LHC. Some of these are confirmations or improved measurements of the Standard Model, while many others are searches for new physical theories.
One of the main interests in the top physics studies at the LHC is an accurate measurement of the top mass. A method to measure the mass of the top quark based on the correlation between J/ψ -muon mass and the top quark mass is described in this thesis. This technique is free of the jet energy scale associated systematic error which plague most top mass measurement. The study shows that with 20 f b−1 of integrated luminosity at 14TeV it is possible to achieve an accuracy of 2.9 GeV
The top quark also plays an important role in the search for new physics, both as a background and as a possible decay product. The experience gained in top quark physics was used to contribute to the Charged Higgs boson search. The discovery of a charged Higgs (H) would be an unambiguous sign of physics beyond the Standard Model. The largest uncertainty in light H searches is the expected ttbar background contribution where the final state includes a truet. In this thesis the results of a search for charged Higgs bosons in 1.03 fb−1 of proton-proton collision data using the t (had)? and t (had)?? channels in ttbar decays are presented. The background was estimated in a data-driven way. In particular, the embedding method was used to estimate the background with true taus. The data agree with the SM expectation leading to a limit on the product of branching ratios BR(t →bH) ? BR(H→t n) > 0.03 − 0.10 for H masses in the range 90-160 GeV.