Penguin Pollution in B->pi pi

Based on a sample of 227 million BBbar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure the branching fraction B(B0 -> pi0pi0) = (1.17 +- 0.32 +- 0.10) x 1e-6, and the asymmetry C(pi0pi0) = -0.12 +- 0.56 +- 0.06. The B0 -> pi0pi0 signal has a significance of 5.0 sigma. We also measure B(B+ -> pi+pi0) = (5.8 +- 0.6 +- 0.4) x 1e-6, B(B+ -> K+pi0) = (12.0 +- 0.7 +- 0.6) x 1e-6, and the charge asymmetries A(pi+pi0) = -0.01 +- 0.1...

This talk contains a short overview of the history of the interplay of the weak and the strong interaction and CP-violation. It describes the phenomenology and the basic physics mechanisms involved in the Standard Model calculations of $K\to\pi\pi$ decays with an emphasis on the evaluation of Penguin operator matrix-elements.

The CP asymmetry in $B^0\to K^+\pi^-$ is expected to be similar to that in $B^+\to K^+\pi^0$. The experimental data however show $\sim 5\sigma$ difference between the two, leading to the so called $\Delta {A}_{K\pi}$ puzzle. Employing sum rule(s) following from (approximate) flavour symmetry, we show that it is possible to accommodate the observed experimental values within the standard model (SM) for a narrow range of parameters. Sub-leading terms can bring the theoretical p...

We present updated measurements of the branching fractions for the modes B0->pi0pi0, B+ -> pi+pi0, and B+ -> K+pi0. We also measure the time-integrated asymmetry C_pi0pi0 and the charge asymmetries A_CP(pi+pi0) and A_CP(K+pi0). Based on a sample of approximately 227 million BBar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure BR(B0 -> pi0pi0) = (1.17 +/- 0.32 +/- 0.10)*10^{-6}, C_pi0pi0 = -0.12 +/- 0.56 +/- 0.06, where the f...

We present a study of non-leptonic B-meson decays, partial widths and CP asymmetries, and discuss the possibilities of determining the penguin contributions through less model-dependent phenomenological analyses. In the last section we employ a specific model to give more definite numerical predictions.

Recently, we have seen interesting progress in the exploration of CP violation in B^0_d -> pi^+ pi^-: the measurements of mixing-induced CP violation by the BaBar and Belle collaborations are now in good agreement with each other, whereas the picture of direct CP violation is still unclear. Using the branching ratio and direct CP asymmetry of B^0_d -> pi^- K^+, this situation can be clarified. We predict A_CP^dir(B_d -> pi^+ pi^-) = -0.24+-0.04, which favours the BaBar result...

We present a method of determining the CKM-angle $\alpha$ by performing simultaneous measurements of the mixing-induced CP asymmetries of the decays $B_d\to\pi^+\pi^-$ and $B_d\to K^0\bar K^0$. The accuracy of our approach is limited by $SU(3)$-breaking effects originating from $\bar b\to \bar ds\bar s$ QCD-penguin diagrams. Using plausible power-counting arguments we show that these uncertainties are expected to be of the same order as those arising through electroweak pengu...

The recently observed $B^-\to K^- \pi^0$, $\bar K^0 \pi^-$ and $\bar B^0 \to K^- \pi^+$ decay modes appear to have nearly equal branching ratios. This suggests that tree and electroweak penguins play an important role, and inclusion of the latter improves agreement between factorization calculation and experimental data. The value $\gamma$ in the range $90^\circle - 130^\circle$ and $220^\circle - 260^\circle$ is favored, while the $\bar B^0 \to \bar K^0 \pi^0$ rate is suppre...

Measurements of the combined branching ratios for $B^\pm \to \pi^\pm K$ and $B_d \to \pi^\mp K^\pm$ allow interesting constraints on the CKM angle $\gamma$, the ratio $r \equiv |T'|/|P'|$ of the current-current and penguin operator contributions to $B_d \to \pi^\mp K^\pm$, and the CP asymmetry in that decay. Present CLEO results for these branching ratios indicate where problems with consistency of the Standard Model may arise in the future. In this paper we discuss scenarios...

It is well known that one can use B -> pi pi decays to probe the CP-violating phase \alpha. In this paper we show that these same decays can be used to search for new physics. This is done by comparing two weak phases which are equal in the standard model: the phase of the t-quark contribution to the b -> d penguin amplitude, and the phase of Bd-Bd(bar) mixing. In order to make such a comparison, we require one piece of theoretical input, which we take to be a prediction for ...