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We report measurements of the branching fractions and direct CP asymmetries (A_{CP}) for B->K pi, pi pi and KK decays (but not pi^0 pi^0) based on the final data sample of 772x10^6 B B-bar pairs collected at the Upsilon(4S) resonance with…

Flavour physics offers interesting probes for the exploration of the Standard Model and the search for new physics. In these lectures, we focus on B- and K-meson decays, introduce the concept of low-energy effective Hamiltonians to describe…

Long-distance effects in exclusive rare semileptonic transitions B -> (K, K*) are analysed within a relativistic quark model. The meson transition form factors, describing the meson amplitudes of the effective weak Hamiltonian, are…

In the limit of flavor SU(3) symmetry, the amplitudes for Bd->pi^+\pi^- and Bs-> K^+ K^- are related to one another. Taking the values of the weak phases beta and gamma from independent measurements, the ratio Rds=BR(Bs->…

We study the implication of the time-dependent CP asymmetry in $B\to\pi^+\pi^-$ decays on the extraction of weak phases taking into account the precise measurement of $\sin 2\beta$, obtained from the ``gold-plated''mode $B\to J/\psi K_S$.…

A class of previously unknown strong-interaction corrections is found to enhance the rate of non-leptonic decays of the b quark by 5-8 percent. This effect decreases the predicted fraction of semi-leptonic decays and brings it into fair…

The recently measured direct CP asymmetries in the processes $D^0\to \pi^+\pi^-$ and $D^0\to K^+K^-$ show a significant deviation from the naive Standard Model expectation. Using a general parameterization of the decay amplitudes, we show…

We present updated measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 60 million Y(4S) to BB…

An overview of recent theoretical developments in rare leptonic B decays is given. New physics effects on branching ratio and CP violation in the decays are analyzed in models beyond SM (supersymmetric models and two Higgs doublet models).

Rare $B$, $D$ and $K$ decays provide interesting probes of the Standard Model (SM), with a potential sensitivity to New Physics (NP) higher than other, more common, decays. Their experimental measurement is challenging, and their…

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…

The recently reported measurements of the CP asymmetry a(psi K) by the BABAR and BELLE collaborations are in good agreement with the standard model (SM) prediction, resulting from the unitarity of the CKM matrix. The so-called minimal…

I give a pedagogical introduction into flavour-changing neutral current interactions of kaons and their role to reveal or constrain physics beyond the Standard Model (SM). Then I discuss the measure $\epsilon_K^\prime$ of direct CP…

We consider three possible scenarios of new physics in B^0_d-\bar{B}^0_d mixing and propose a simple framework for analyzing their effects. This framework allows us to study the CP asymmetry in semileptonic B_d decays ({\cal A}_{SL}) and…

New measurements of the CP asymmetry in B->\psi K_S, a_{\psi K_S}, by the BABAR and BELLE collaborations are consistent with the Standard Model prediction for sin2\beta. These measurements, however, leave open the possibility that a_{\psi…

We analyze the $B \to \phi K^{*}$ polarization puzzle in the Minimal Supersymmetric Standard Model (MSSM) including the neutral Higgs boson (NHB) contributions. To calculate the non-factorizable contributions to hadronic matrix elements of…

Semileptonic and leptonic B decays are analyzed in the framework of the relativistic quark model. Special attention is payed to the decays involving $\tau$ lepton. It is found that the calculated particular decay branching fractions are…

We report an observation of the decay B^\pm -> \phi \phi K^\pm and evidence for B^0 -> \phi \phi K^0. These results are based on a 414 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^+e^- collider…

We review three recent results of the CDF collaboration on Bs suppressed decays: the first search for CP--violation in the Bs-->phi phi decay, where two CP--violating asymmetries expected to be zero in the Standard Model are measured, and…

The observation of a sizable direct CP asymmetry in the inclusive decays B -> X_s gamma would be a clean signal of New Physics. In the Standard Model, this asymmetry is below 1% in magnitude. In extensions of the Standard Model with new…