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

The decays $B_d\to\pi^+\pi^-$ and $B_s\to K^+K^-$ provide an interesting strategy to extract the CKM angle $\gamma$ at ``second-generation'' $B$-physics experiments of the LHC era. A variant for ``first-generation'' experiments can be obtained, if $B_s\to K^+K^-$ is replaced by $B_d\to\pi^\mp K^\pm$. We show that the most recent experimental results for the CP-averaged $B_d\to\pi^+\pi^-$ and $B_d\to\pi^\mp K^\pm$ branching ratios imply a rather restricted range for the corres...

A major problem in the determination of the the CP angle $\alpha$, that should be measured through modes of the type $B_d, \bar{B}_d \to \pi \pi , \cdots ,$ is the uncertainty coming from Penguin diagrams. We consider the different ground state modes $\pi \pi$, $\pi \rho$, $\rho \rho$, and, assuming the FSI phases to be negligible, we investigate the amount of uncertainty coming from Penguins that can be parametrized by a dilution factor $D$ and an angle shift $\Delta \alpha$...

The decay $B^0 \to K^0 \pi^0$, dominated by a $b \to s$ penguin amplitude, holds the potential for exhibiting new physics in this amplitude. In the pure QCD penguin limit one expects $\ckp = 0$ and $\skp = \sin 2 \beta$ for the coefficients of $\cos \Delta m t$ and $\sin \Delta m t$ in the time-dependent CP asymmetry. Small non-penguin contributions lead to corrections to these expressions which are calculated in terms of isospin-related $B\to K\pi$ rates and asymmetries, usi...

Time-dependent CP violation is measured in the $B^0\rightarrow J/\psi\pi^+\pi^-$ channel for each $\pi^+\pi^-$ resonant final state using data collected with an integrated luminosity of 3.0 fb$^{-1}$ in $pp$ collisions using the LHCb detector. The final state with the largest rate, $J/\psi\rho^0(770)$, is used to measure the CP-violating angle $2\beta^{\rm eff}$ to be $(41.7\pm 9.6_{-6.3}^{+2.8})^{\circ}$. This result can be used to limit the size of penguin amplitude contrib...

We present the most complete analysis of the penguin correction to the extraction of the standard-model parameter sin(2\phi_1) from the B^0 -> J/psi K_S decay up to leading power in 1/m_b and to next-to-leading order in \alpha_s, \phi_1 being the weak phase, m_b the b quark mass, and \alpha_s the strong coupling constant. The deviation \Delta S_{J/psi K_S} of the mixing-induced CP asymmetry from sin(2\phi_1) and the direct CP asymmetry A_{J/psi K_S} are both found to be of O(...

We reanalyze the decay $B_d\to\pi^+\pi^-$ without assuming dominance of QCD penguins with internal top-quark exchanges. In that case the weak phase of the $\bar b \to\bar d$ QCD penguin amplitude is not related in a simple way to the CKM angle $\beta$. Nevertheless it is still possible to extract the CKM angle $\alpha$ in a transparent and almost model-independent way from the time-dependent CP-violating asymmetry of the transition $B_d\to\pi^+\pi^-$. Aside from that CP asymm...

A reliable prediction for $CP$ violation in $B^{0}_{d}$ vs $\bar{B}^{0}_{d}\rightarrow \pi^{+}\pi^{-}$ suffers from the penguin-diagram induced uncertainty. With the help of SU(3) relations, we show that both the magnitude and strong phase shift of the penguin amplitude can be approximately determined only from the branching ratios of $B^{0}_{d}\rightarrow \pi^{+}\pi^{-}$, $B^{0}_{d}\rightarrow K^{+}\pi^{-}$, and $B^{+}_{u}\rightarrow K^{0}\pi^{+}$.

Measurements of the time-dependent CP asymmetry in the decay $B^0_d (t) \to \pi^+ \pi^-$ and its charge conjugate by the BELLE and BABAR collaborations currently yield $C_{\pi \pi}^{+-} = -0.46 \pm 0.13$ and $S_{\pi \pi}^{+-} = -0.74 \pm 0.16$, characterizing the direct and mixing-induced CP asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis l...

The role of penguin amplitudes in CP violating $B$ decays is reviewed, emphasizing recent progress in the analysis of electroweak penguin contributions. It is shown how these terms are included in a model-independent manner when measuring the weak phase $\alpha$ in $B\to\pi\pi$ using isospin symmetry, and when determining the phase $\gamma$ from $B\to K\pi$ applying flavor SU(3). Uncertainties due to rescattering effects in $B\to K\pi$ are discussed.

We present a new method for measuring the CP phase \alpha. It requires the measurement of the pure penguin decays Bd(t) -> K(*) Kbar(*) and B_s -> K(*) Kbar(*). The method is quite clean: we estimate the theoretical uncertainty to be at most 5%. By applying the method to several K(*) Kbar(*) final states, \alpha can be extracted with a fourfold ambiguity. An additional assumption reduces this ambiguity to twofold: {\alpha, \alpha + \pi}. Since no \pi0 detection is needed, thi...