Analysis of the B0d and Lambdab decay channels within the ATLAS detector at LHC

Abstract

Abstract. This paper describes the study of the possible measurement of parameters of the Stan­dard Model, which relate to CP violation with the ATLAS detector and the lifetime ratio of Ag and Bwhich is of great theoretical interest. This is done in two specific channels.
The Bmesons and Ag baryon and its conjugate .Ag are observed with the ATLAS experi­ ment at LHC through their fully reconstructed decays **** and *****. The decays are reconstructed in 40 pb- 1 of data taken in 2010 and 1.2 fb-1 of data in 2011. The mass distributions obtained are fitted using an unbinned maximum
likelihood fit. In order to extract the lifetime of the Bmeson a simultaneous unbinned maximum likelihood fit to the reconstructed Bmass and proper decay time is performed. The measured Band Ag!.i\g masses and the Blifetime are consistent with the world average values. Capability of the ATLAS detector to make a precise lifetime measurement was demonstrated. In order to under­
stand the detector performance, material effects, the background and interesting physics events, six Monte Carlo samples are generated for the signals and the background.