Strategies for precision measurements of the charge asymmetry of the W boson mass at the LHC within the ATLAS experiment

Abstract

This thesis dissertation presents a prospect for a measurement of the charge asymmetry of the W boson mass (MW+ - MW-) at the LHC within the ATLAS experiment. This measurement is of primordial importance for the LHC experimental program, both as a direct test of the charge sign independent coupling of the W bosons to the fermions and as a mandatory preliminary step towards the precision measurement of the charge averaged W boson mass. This last pragmatic point can be understood since the LHC specific collisions will provide unprecedented kinematics for the positive and negative channels while the SPS and Tevatron collider produced W+ and W- on the same footing. For that reason, the study of the asymmetries between W+ and W- in Drell--Yan like processes (production of single W decaying into leptons), studied to extract the properties of the W boson, is described thoroughly in this document. Then, the prospect for a measurement of MW+ - MW- at the LHC is addressed in a perspective intending to decrease as much as possible the systematic errors that will inevitably comes from the misunderstanding of both phenomenological and apparatus modeling. For that matter strategies have been devised specifically for the present measurement to display robustness with respect to the main uncertainties. These strategies consist of introducing new observables along with considering specific LHC running modes and configurations of the ATLAS tracker. Eventually we show that the present (2009) precision can be improved at the LHC by a factor of 20 and argue that such a precision is beyond the reach of the standard measurement and calibration methods imported to the LHC from the Tevatron program.Comment: 199 pages, 95 figures, 10 tables, Ph.D. dissertatio