A search for the B 0 → D + s D − s decay using multivariate techniques at LHCb Master Thesis

A search for the decay B → D s D− s is conducted using the 3 fb−1 of Run 1 data collected by the LHCb experiment. The use of new DNN classifiers recently added to TMVA is investigated in the selection process. A small excess of 2 sigma is measured in the signal region. The use of Run 2 data was envisaged, but the changes in the dataflow and the absence of Run 2 MC did not allow a precise efficiency calculation on the Run 1+Run 2 data. The measured branching fraction using the LHCb Run 1 data is: B(B → D s D− s ) = [6.64± 2.15 (stat)± 2.62 (syst)± 0.76 (norm) ] · 10−5 This is in agreement with previous limits and compatible with the SM prediction.