Some aspects of rare B decays and CP violation

Abstract

In this thesis, we present our study of CP violation in the B meson system and also a study of some of the rare B decay modes, where we look for the possible manifestation of new physics. We consider the possibility of extracting the CKM angle ° with Bc de-b cays. The modes B§c ! (D0)D§s ! (K¤+K¡)D§s and B§c ! ( ¹D0)D§s ! (K¤+K¡)D§s are found to be well suited for the extraction of °. Since a large number of Bc mesons are expected to be produced at the LHC, it would be very interesting to explore the determination of ° with these modes. These channels are described by color suppressed tree diagrams only and are free from penguin contributions. The methods presented here may be well suited to determine the CKM angle ° and the combination 2¯ + °. We then consider the hadronic decay modes B§(0) ! f0(980)K§(0), in- volving a scalar and a pseudoscalar meson in the ¯nal state. We compute the branching ratio and the CP asymmetry parameter both in the SM and in the R-parity violating (RPV) supersymmetric model. These decay modes are dominated by the loop induced b ! s¹qq (q = s; u; d) penguins along with a small b ! u tree level transition (for B+ ! f0K+) and annihilation diagrams. Therefore, the standard model expectation of direct CP viola- tion is negligibly small and the mixing induced CP violation parameter in the mode B0 ! f0KS is expected to give the same value of sin(2¯), as ex- tracted from B0 ! J=ÃKS but with opposite sign. Using the generalized factorization approach, we ¯nd the direct CP violation in the decay mode B+ ! f0K+ to be of the order of a few percent. We then study the e®ect of the R-parity violating supersymmetric model and show that the direct CP violating asymmetry in B+ ! f0(980)K+ could be as large as » 80% and the mixing-induced CP asymmetry in B0 ! f0KS (i.e., ¡Sf0KS ) could deviate signi¯cantly from that of sin(2¯)J=ÃKS . The results of the study of the decay modes B ! f0K(¼), with f0 being f0(1370; 1500), in the SM are also presented....