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

A major goal in B physics is measuring the CP-violating asymmetry in the decay $B^0 \rightarrow \pi^+ \pi^-$. In order to determine one of the phase angles in the CKM matrix from this decay it is necessary to determine the influence of the penguin amplitude. Here we show how, using $SU(3)$ symmetry, the penguin effect can be approximately determined from the ratio of the decay rates of $B^0 \rightarrow K^+ \pi^-$ and $B^0 \rightarrow \pi^+ \pi^-$.

We present a method to measure the CKM phase $\alpha$ and the tree and penguin (strong and electroweak) amplitudes in $B \rightarrow \pi \pi$ decays, based on isospin consideration and the weak assumption that all tree amplitudes have a common strong phase and all penguin amplitudes have a different common phase. The method needs only the time-independent measurements of the relevant decay rates in $B \rightarrow \pi \pi$. We also propose a method to experimentally examine th...

We study the penguin pollution in 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, m_b being 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(10^{-3}) in a formalism that combines the QCD-improved factorization and perturbative QCD approaches.

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...

In this talk we show that, unlike other pure $b\to d$ penguin processes, the decay $\bs(t)\to\phi\ks$ is dominated by a single amplitude, that of the internal $t$-quark. Thus, the indirect CP asymmetry in this decay probes $\sin 2\beta$. This cancellation holds for most part of the parameter space and error on $\sin 2\beta$ is less than 10%. By measuring the direct CP asymmetry, one can get a better idea of the probable error on $\sin 2\beta$.

Isospin and flavor SU(3) set stringent bounds on penguin pollution in $B^0(t)\to \rho^+\rho^-$, providing a theoretically precise determination of $\alpha\equiv \phi_2 $, $\alpha = (91\pm 7_{\rm exp}\pm 3_{\rm th})^\circ$. Isospin breaking in a sum rule for $B\to K\pi$ rates is shown to be suppressed. A similar sum rule holds for CP asymmetries in $B\to K\pi$. Violation of these sum rules would be evidence for an anomalous $\Delta I=1$ piece in ${\cal H}_{\rm eff}$.

Time-dependent CP asymmetry measurements in $D\to h^+h^-$ decays, where $h=\pi$ or $\rho$ can be used to constrain the angle $\beta_c$ of the $cu$ unitarity triangle up to theoretical uncertainties. Here we discuss the theoretical uncertainty from penguin contributions that can be mitigated through the use of isospin analyses. We show that uncertainty from penguin pollution on a measurement of $\beta_c$ (or alternatively the mixing phase) in $D^0\to \pi^+\pi^-$ ($\rho^+\rho^-...

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 ...

In the neutral B meson system, it is possible to measure the CKM angle alpha using the decay mode b -> u ubar d in the presence of pollution from gluonic b -> d penguin decays. Here the recent status of the measurements of CP-violating asymmetry parameters using time-dependent analyses in B -> pi+pi- and B -> rho pi decays and the perspectives of a sin2alpha measurement are presented.

We present strategies for determining electroweak penguins from experimental data. Using the CKM-angle $\gamma$ as one of our central inputs and making some reasonable approximations, we show that the $\bar b\to\bar s$ electroweak penguin amplitude can be determined in a two-step procedure involving i) BR$(B^+\to\pi^0K^+)$, BR$(B^-\to\pi^0K^-)$, BR$(B^+\to\pi^+K^0)$ and ii) either BR$(B^0_d\to\pi^-K^+)$, BR$(\bar B^0_d\to\pi^+K^-)$ or $\acp(t)$ of the mode $B_s\to K^+K^-$. Th...