Study Of Neutral Bs Mixing In A Family Non-unlversal Z' Model

The Standard Model of elementary particle is a theoretical model based on the gauge group SU(3)_c? SU(2)_L?U(l)_y,which purports to describe the strong and electroweak interactions of fundamental particles. During the past thirty years, it has survived assorted experimental tests extensively and is the best theory for describing the dynamics of fundamenal paticles until now. However, the Standard Model itself has some problems that have not been solved reasonably yet, which is not perfect. All these questions may indicate that the Standard Model is not an ultimate theory but an effective theory at low scale, which will provide enough space for developing new physics beyond the Standard Model, i.e. at the higher energy scale, which there should exist some new and more basic theories. In recent decades, heavy flavour physics, especially B physics, is very attracted people's attention and become a very popular and frontier areas. One of the important reasons is that it is not only reveals the very short distance of strong interaction physics, more important is that it is high precise inquiry CP violation, rare decay and flavor changing neutral current processes, and provides a ideal place in testing the standard model and looking for new physics.In this thesis, we focus on some current very interesting puzzles in B meson mixing to made detailed research and analysis and to pursue possible solutions with the specific family non-universal Z model. The main body of the thesis is that motivated by the very recent measurements performed at the LHCb and the Tevatron of the neutral Bs mixing, in this paper we revisit it in a family non-universal Z model, to check if a simultaneous explanation for all the mixing observables, especially for the like-sign dimuon charge asymmetry observed by the DO collaboration, could be made in such a specific model. In the first scenario where the Z boson contributes only to the off-diagonal element Ms12; it is found that, once the combined constraints fromâ–³MS, s andâ–³Ts are imposed, the model could not explain the measured flavour-specific CP asymmetry asfs, at least within its lo ranges. In the second scenario where the NP contributes also to the absorptive part T312via tree-level Z'-induced bâ†'scc operators, we find that, with the constraints fromâ–³MS; s and the indirect CP asymmetry in Bdâ†'JlψKs taken into account, the present measured lo experimental ranges for asfs could not be reproduced too. Thus, such a specific Z model could not simultaneously explain the present data on neutral Bs mixing. Future improved measurements from the LHCb and the proposed super B experiments, especially of the flavour specific CP asymmetries, are expected to shed light on the issue.