New bound on penguin pollution in B^0(t) --> pi^+ pi^-

The unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix has been well established by both direct and indirect measurements without any evidence of discrepancy. The CKM weak phase $\alpha$ is directly measured using an isospin analysis in $B\rightarrow \pi\pi$ and $B\to \rho\rho$ assuming that electroweak penguin contributions are ignorable. However, electroweak penguins are sensitive to NP, hence, it is important to experimentally estimate their effects. We determine the ...

Theoretically motivated smallness of the penguin amplitude in $B \to \pi \pi$ decays allowes to calculate the value of the unitarity triangle angle $\alpha (\phi_2)$ with good accuracy. The relatively large branching ratio of the decay into $\pi^0 \pi^0$ is explained by the large value of FSI phase difference between $\Delta I = 1/2$ and $\Delta I = 3/2$ tree amplitudes.

Recent theoretical results of the standard model expectations on $\sin2\beta_{\rm eff}$ from penguin-dominated $b \to s$ decays are briefly reviewed.

We show that, unlike other pure b -> d penguin processes, the decay Bs(t) -> phi K_s is dominated by a single amplitude, that of the internal t-quark. The contributions of the u- and c-quark operators each vanish due to a cancellation between the (V-A) \otimes (V-A) and (V-A) \otimes (V+A) matrix elements. Thus, the indirect CP asymmetry in this decay probes sin 2\beta. Although this cancellation is complete only for certain values of the s- and b-quark masses, the theoretica...

We present an {\it algebraic} isospin approach towards a more straightforward and model-independent determination of the weak phase $\alpha$ (or $\phi_2$) and QCD penguin pollution in $B\to \pi\pi$ decays. The world averages of current experimental data allow us to impose some useful constraints on the isospin parameters of $B\to \pi\pi$ transitions. We find that the magnitude of $\alpha$ (or $\phi_2$) extracted from the indirect CP violation in $\pi^+\pi^-$ mode is in agreem...

Theoretical errors in the extraction of alpha from B -> pi^+ pi^-, rho^+ rho^-, rho pi decays are usually given in terms of upper bounds on alpha_eff-alpha obtained from isospin or from SU(3) relations, where alpha_eff is measured through CP asymmetries. We show that mild assumptions about magnitudes and strong phases of penguin and tree amplitudes (|P/T| < 1 and |delta| < pi/2) in B -> pi pi and B -> rho rho, imply alpha_eff > alpha, thus reducing by a factor two the error i...

Although recent experimental results in b-->s penguin process seem to be roughly consistent with the standard model predictions, there may be still large possibilities of new physics hiding in this processes. Therefore, here we investigate systematically the potential new physics effects that may appear in time-dependent CP asymmetries of B --> phi K^0, B--> eta^\prime K^0 and B--> K^0 \pi^0 decay modes, by classifying the cases for the values of the mixing-induced indirect C...

We discuss a method for extracting CP phases from pairs of B decays which are related by flavor SU(3). One decay (B0 -> M1 M2) receives a significant bbar -> dbar penguin contribution. The second (B' -> M1' M2') has a significant bbar -> sbar penguin contribution, but is dominated by a single amplitude. CP phase information is obtained using the fact that the B' -> M1' M2' amplitude is related by SU(3) to a piece of the B0 -> M1 M2 amplitude. The leading-order SU(3)-breaking ...

We investigate a class of models for new physics which could produce a large difference in sin 2 beta between B0-> J/\psi K(S) and the ``pure penguin'' mode B0-> phi K(S). In such models, the dominant effect is through a Z-penguin and therefore a pattern of deviation in sin 2beta as measured in B0-> chi(1) K(S); eta(c) K(S); J/\psi K(S) and psi-prime K(S) is predicted. If the preliminary data concerning the discrepancy between J/\psi K(S) and phi K(S) proves correct in magnit...

We present the new and updated $BABAR$ measurements of CP-violation studies for many $b\to s $ penguin decay modes. We report the first observation of mixing-induced CP-violation in $B^0 \to \eta ^{'} K^0$ with a significance (including systematic uncertainties) of 5.5$\sigma$. We also present the first observation of the decay $B^0 \to \rho ^0 K^0$. Using the time-dependent Dalitz plot analysis of $B^0\to K^+K^- K^0$ decay, the CP-parameters $\mathcal A_{CP}$ and $\beta_{eff...