The Muon Detection System and W Z --> 3l̳(e̳, [mu]) cross section measurement at CMS

Abstract

The startup of the Large Hadron Collider will allow scientists to probe energy scales that existed picoseconds after the Big Bang. Monte Carlo samples of many Standard Model processes are produced to simulate the conditions in the Compact Muon Solenoid detector. Data analysis techniques are developed to measure the cross section of the W Z --> 3l(e, [mu]) decay channel. The results are [sgima]all = 723.4 ± 27.6(stat.) ± 144.7(syst.) fb for integrated luminosity 1 fb-1. Cross section measurements deduced by our data analysis techniques agree with the theoretical predictions, [sigma] pred. all = 708 ± 26.6 fb. The selection of W Z --> 3l events gave 43.5 ± 6.6 signal events with 6.4 ± 2.5 background events, enough to claim an observation at the level of five standard deviations. The understanding of this process will aid in the search for the Higgs boson, as well as in the search for new physics in the early stages of the operation of the detector.