TY  - GEN
N2  - This work presents a method to extract the CP-violating phase phi_s using the Bs meson decay Bs -> J/psi phi. The determination of phi_s is one of the key measurements of the physics program of the LHCb experiment. The phase phi_s arises from the interference between Bs mixing and the decay and is predicted by the Standard Model to be phi_s = (-0.0363 +- 0.0017) rad. Physics processes beyond the Standard Model can affect the Bs mixing amplitude and lead to deviations from this prediction. The precision measurement of phi_s therefore constitutes an indirect search for New Physics. In the scope of this thesis an unbinned maximum likelihood method to extract phi_s has been implemented. Since the decay Bs -> J/psi phi is a pseudoscalar to vector-vector transition the extraction method depends on both decay time and decay angles. Acceptance and resolution effects are also taken into account. The procedure is successfully tested on fully simulated events and fast simulated data. It is used to analyze data taken by the LHCb experiment in 2010 which correspond to an integrated luminosity of 36 pb^-1. With a flavor blind analysis the decay width difference DG_s is determined to be DG_s = (0.084 +- 0.112 +- 0.014) ps^-1 under the assumption of no CP violation. Using a Bs production flavor dependent analysis two-dimensional confidence regions for phi_s and DG_s are extracted. The Standard Model prediction is found to agree within 1.0 standard deviations with the data. In one dimension the confidence interval for phi_s at 68.3% confidence level is determined to be [-2.78, -0.39] rad. 
AV  - public
KW  - CP Verletzung 
KW  -  Bs Mischung 
KW  -  Bs -> J/psi phi 
KW  -  phi_s 
KW  -  LHCbCP violation 
KW  -  Bs mixing 
KW  -  Bs -> J/psi phi 
KW  -  phi_s 
KW  -  LHCb
A1  - Langenbruch, Christoph
TI  - Measurement of the Bs mixing phase in the decay Bs -> J/psi phi with the LHCb experiment
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/12730/
Y1  - 2011///
ID  - heidok12730
ER  -