Searching for new physics in the angular distribution of B^0 -> phi K^* decay

Motivated by the possible discrepancy between the observed CP asymmetry and that of standard model expectation in the decay mode B^0 -> phi K_S, we study the corresponding vector vector decay mode B^0 -> phi K^*. In order to obtain decisive information regarding the CP violating effect, we made the angular distribution analysis of the decay products, where both the outgoing vector mesons decay into two pseudoscalars. Furthermore, we study the possible effects of new physics using the angular distribution observables.Comment: LaTex, 16 pages, 1 figur

Explaining B \to K pi anomaly with non-universal Z' boson

We study the effect of non-universal $Z'$ boson in the decay modes $B \to K \pi$. In the standard model these modes receive dominant contributions from $b \to s$ QCD penguins. Therefore, in this limit one expects $S_{\pi^0 K^0} \approx \sin 2 \beta$, $A_{\pi^0 K^0} \approx 0$ and $A_{\pi^0 K^-} \approx A_{\pi^+ K^-}$. The corrections due to the presence of small non-penguin contributions is found to yield $S_{\pi^0 K^0} > \sin 2 \beta$ and $\Delta A_{CP}(K \pi) \simeq 2.5$. However, the measured value of $S_{\pi^0 K^0}$ is less than $\sin 2 \beta$ and $\Delta A_{CP}(K \pi) \simeq 15$. We show the model with a non-universal $Z'$ boson can successfully explain these anomalies.Comment: 11 pages, 3 figure

Bs0−Bˉs0B_s^0 - \bar B_s^0 mixing and b→sb \to s transitions in isosinglet down quark model

The recent observation of the mass difference in $B_s$ system seems to be not in complete agreement with the corresponding standard model value. We consider the model with an extra vector like down quark to explain this discrepancy and obtain the constraints on the new physics parameters. Thereafter, we show that with these new constraints this model can successfully explain other observed deviations associated with $b \to s$ transitions, namely, $B_s \to \psi \phi$, $B\to K \pi$ and $B\to \phi K_s$.Comment: 19 pages, 6 figure

Probing new physics in B -> f_0(980) K decays

We study the hadronic decay modes $B^{\pm(0)} \to f_0(980) K^{\pm(0)}$, involving a scalar and a pseudoscalar meson in the final state. These decay modes are dominated by the loop induced $b \to s \bar q q(q=s,u,d)$ penguins along with a small $b \to u$ tree level transition (for $B^+ \to f_0 K^+$) and annihilation diagrams. Therefore, the standard model expectation of direct CP violation is negligibly small and the mixing induced CP violation parameter in the mode $B^0 \to f_0 K_S$ is expected to give the same value of $\sin(2\beta)$, as extracted from $B^0 \to J/\psi K_S$ but with opposite sign. Using the generalized factorization approach we find the direct CP violation in the decay mode $B^+ \to f_0 K^+$ to be of the order of few percent. We then study the effect of the R-parity violating supersymmetric model and show that the direct CP violating asymmetry in $B^+ \to f_0(980) K^+$ could be as large as $\sim 80$ and the mixing induced CP asymmetry in $B^0 \to f_0 K_S$ (i.e., $-S_{f_0 K_S}$) could deviate significantly from that of $\sin(2 \beta)_{J/\psi K_S}$.Comment: 18 pages, 5 figures, version to appear in Phys. Rev.

Study of FCNC mediated rare B_s decays in a single universal extra dimension scenario

We study the rare semileptonic and radiative leptonic B_s decays in the universal extra dimension model. In this scenario, with a single extra dimension, there exists only one new parameter beyond those of the standard model, which is the inverse of the compactification radius R. We find that with the additional contributions due to the KK modes the branching ratios of the rare B_s decays are enhanced from their corresponding standard model values and the zero point of the forward backward asymmetries are shifted towards the left.Comment: 19 pages, 7 figures, version to appear in Phys. Rev.

Analysis of direct CP violation in B−→D0Ds−,D0D−B^- \to D^0 D_s^-, D^0 D^- decays

We investigate the possibility of observing the direct CP violation in the decay modes $B^- \to D^0 D_s^-$ and $D^0 D^-$ within the Standard Model. Including the contributions arising from the tree, annihilation, QCD as well as electroweak penguins with both time- and space-like components, we find that the direct CP asymmetry in $B^- \to D^0 D_s^-$ is very small $\sim 0.2$ % but in $B^- \to D^0 D^-$ decay it can be as large as 4%. Approximately $10^7$ charged $B$ mesons are required to experimentally observe the CP asymmetry parameter for the later case. Since this is easily accessible with the currently running B factories, the decay mode $B^- \to D^0 D^-$ may be pursued to look for CP violation.Comment: Latex, 14 page