Interpreting the time-dependent CP asymmetry in B0→π0KSB^0 \to \pi^0 K_S

Flavor SU(3) is used for studying the time-dependent CP asymmetry in $B^0 \to \pi^0 K_S$ by relating this process to $B^0\to \pi^0\pi^0$ and $B^0 \to K^+K^-$. We calculate correlated bounds on $S_{\pi K} - \sin 2\beta$ and $C_{\pi K}$, with maximal magnitudes of 0.2 and 0.3, where $S_{\pi K}$ and $C_{\pi K}$ are coefficients of $\sin\Delta mt$ and $\cos\Delta mt$ in the asymmetry. Stronger upper limits on $B^0 \to K^+K^-$ are expected to reduce these bounds and to imply nonzero lower limits on these observables. The asymmetry is studied as a function of a strong phase and the weak phase $\gamma$.Comment: 11 pages, 2 figures, to be published in Phys. Lett. B. Some equations corrected leading to small changes in figure

Precision Tests of Flavor and CP violation in B Decays

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 ${\cal H}_{\rm eff}$.Comment: Reference added; Invited talk presented at the First Workshop on Theory, Phenomenology and Experiments in Heavy Flavor Physics, Anacapri, Italy, 29-31 200

CP violation in B meson decays

Recent CP asymmetry measurements in tree-dominated processes, $B^0\to \pi^+\pi^-, \rho^+\rho^-, \rho^{\pm}\pi^{\mp}, B^+\to DK^+$, and in penguin-dominated decays, $B \to \pi^0 K_S, \eta' K_S, \phi K_S$, are interpreted in the framework of the Kobayashi-Maskawa (KM) mechanism of CP violation. The KM phase emerges as the dominant source of CP violation in tree-dominated decays, which are beginning to constrain the unitarity triangle beyond other constraints. Improving precision of CP asymmetry measurements in penguin-dominated decays may indicate the need for new physics.Comment: Talk presented at the Sixth International Conference on Hyperons, Charm and Beauty Hadrons, IIT, Chicago, June 27--July 3 200

Enhanced effects on extracting \gamma from untagged B^0 and B_s decays

The weak phase \gamma can be determined using untagged B^0\to DK_S or B_s\to D\phi, D\eta^{(')} decays. In the past, the small lifetime difference y\equiv \Delta\Gamma/(2\Gamma) has been neglected in B^0, while the CP violating parameter \epsilon\equiv 1-|q/p|^2 has been neglected in both B^0-\bar B^0 and B_s-\bar B_s mixing. We estimate the effect of neglecting y and \epsilon. We find that in D decays to flavor states this introduces a systematic error, which is enhanced by a large ratio of Cabibbo-allowed to doubly Cabibbo-suppressed D decay amplitudes.Comment: one reference added, to be submitted for publication in Physics Letters

Corrections to sin(2 beta) from CP asymmetries in B^0 -> (pi^0,rho^0,eta,eta^',omega,phi) K_S decays

Neglecting smaller amplitudes the time-dependent CP asymmetry in penguin-dominated b -> s q \bar q transitions (such as B -> phi K_S) is expected to equal sin(2 beta), an expectation not borne out by the present average experimental data. I compute and discuss the correction due to the smaller amplitudes in the framework of QCD factorization.Comment: 11 pages, 2 figues, LaTe

CKM Phases from CP Asymmetries

Measuring phases in the Cabibbo-Kobayashi-Maskawa matrix through CP asymmetries in B decays is a major goal of current and future experiments. Methods based on charge-conjugation and isospin symmetries involve very little theoretical uncertainties, while schemes based on flavor SU(3) involve uncertainties due to SU(3) breaking. Resolving these uncertainties requires further studies involving a dialogue between theory and experiments.Comment: minor corrections, several references added and update

Implications for CP asymmetries of improved data on B→K0π0B \to K^0 \pi^0

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, using information about strong phases from experiment. We study the prospects for incisive tests of the Standard Model through examination of these corrections. We update a prediction \ckp=0.15\pm 0.04, pointing out the sensitivity of a prediction \skp\approx 1 to the measured branching ratio for $B^0\to K^0\pi^0$ and to other observables.Comment: Note added, to be published in Physics Letters

Studying New Physics Amplitudes in Charmless B_s Decays

A method based on flavour SU(3) is proposed for identifying and extracting New Physics (NP) amplitudes in charmless $\Delta S=1$ $B_s$ decays using time-dependent CP asymmetries in these decays and in flavour SU(3) related $\Delta S=0$ decays. For illustration, we assume a hierarchy, $\sim 1: \lambda : \lambda^2$ ($\lambda=0.2$), between a dominant $\Delta S=1$ penguin amplitude, a NP amplitude and a Standard Model amplitude with weak phase $\gamma$. An uncertainty from SU(3) breaking corrections, reduced by using ratios of hadronic amplitudes, is further suppressed by a factor $\lambda$. We discuss examples for pairs of decays into two neutral vector mesons, $B_s\to\phi\phi, B_s\to\phi \bar K^{*0}$ and $B_s\to K^{*0}\bar K^{*0}, B^0\to K^{*0}\bar K^{*0}$, where the magnitude of the NP amplitude, its weak and strong phases can be determined.Comment: typo corrected, reference added, submitted to Physics Letters

Suppression of flavor symmetry breaking in B decay sum rules

While flavor symmetries are useful for studying hadronic B decays, symmetry relations for amplitudes and decay rates are usually violated by first order symmetry breaking corrections. We point out two cases in which first order symmetry breaking is suppressed by a small ratio of amplitudes: (1) An isospin sum rule for four $B\to K\pi$ decays, where isospin breaking is shown to be negligible. (2) An SU(3) sum rule for pairs of $B\to K\pi$ and $B\to K\eta_8$, generalized to pairs of $B\to K\pi, B\to K\eta$ and $B\to K\eta'$.Comment: 11 pages, small corrections, one reference added, submitted to Physics Letters

Recent measurements of sin2b at BaBar

The angle beta is the most accurately measured quantity that determines the Unitarity Triangle. In this article I review the various measurements of this angle performed by the BaBar Collaboration, and discuss their implications in the search for new physics.Comment: 5 pages, 4 figures, contributed to the Proceedings of BEAUTY 200