%0 Generic
%A Krocker, Georg Alexander
%D 2013
%F heidok:15769
%R 10.11588/heidok.00015769
%T Development and calibration of a same side kaon tagging  algorithm and measurement of the B_s^0 – B_s^0 bar oscillation frequency Δm_s at the LHCb experiment
%U https://archiv.ub.uni-heidelberg.de/volltextserver/15769/
%X This thesis presents a so called same side kaon tagging algorithm, which is used in the determination of the production flavour of B_s^0 mesons. The measurement of the B_s^0 – B_s^0 bar oscillation frequency ΔDelta ms in the decay B_s^0 -> D_s^- π^+ is used to optimise and calibrate this algorithm. The presented studies are performed on a data set  corresponding to an integrated luminosity of L = 1.0 fb^-1 collected by the LHCb experiment in 2011. The same side kaon tagging algorithm, based on multivariant classifiers, is developed, calibrated and tested using a sample of about 26,000 reconstructed B_s^0 -> D_s^- π^+ decays. An effective tagging power of ε_eff = ε_tag(1 - 2ω)^2 = 2.42 +- 0.39% is achieved. Combining the same side kaon tagging algorithm with additional flavour tagging algorithms results in a combined tagging performance of ε_eff = ε_tag(1 - 2ω)^2 = 5.13 +- 0.54%. With this combination, the B_s^0 – B_s^0 bar oscillation frequency is measured to be Δm_s = 17.745 +- 0.022 (stat.) +- 0.006 (syst.) ps^-1, which is the most precise measurement to date.