This article reports world averages of measurements of b-hadron, c-hadron, and tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through the end of 2011. In some cases results available in the early part of 2012 are included. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays and CKM matrix elements.

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Averages of b-hadron, c-hadron, and tau-lepton properties as of early 2012

We update the profile of the CKM matrix. The apex (rhobar,etabar) of the Unitarity Triangle is given by means of a global fit. We propose to include therein sin2alpha from the CP-violating asymmetries in B0->rho+rho-, using isospin to discriminate the penguin contribution. The constraint from epsilon'/epsilon is briefly discussed. We study the impact from the measurement of the rare decay K+->pi+nunu-bar, and from a future observation of KL->pi0nunubar. The B system is investigated in detail, beginning with 2beta+gamma and gamma from B0->D(*)+-pi-+ and B+->D(*)0K+. A significant part of this paper is dedicated to B decays into pipi, Kpi, rhopi and rhorho. Various phenomenological and theoretical approaches are studied. Within QCD Factorization we find a remarkable agreement of the pipi and Kpi data with the other UT constraints. A fit of QCD FA to all pipi and Kpi data leads to precise predictions of the related observables. We analyze separately the B->Kpi decays, and in particular the impact of electroweak penguins in response to recent phenomenological discussions. We do not observe any unambiguous sign of New Physics, whereas there is some evidence for potentially large rescattering effects. Finally we use a model-independent description of a large class of New Physics effects in both BBbar mixing and B decays, namely in the b->d and b->s gluonic penguin amplitudes, to perform a new numerical analysis. Significant non-standard corrections cannot be excluded yet, however standard solutions are favored in most cases.

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CP Violation and the CKM Matrix : Assessing the Impact of the Asymmetric B Factories

Averages of B-Hadron, C-Hadron, and tau-lepton properties as of early 2012

We study model-independently the implications of nonstandard scalar and pseudoscalar interactions for the decays $\stackrel{\ensuremath{\rightarrow}}{b}s\ensuremath{\gamma},$ $\stackrel{\ensuremath{\rightarrow}}{b}sg,$ $\stackrel{\ensuremath{\rightarrow}}{b}s{\mathcal{l}}^{+}{\mathcal{l}}^{\ensuremath{-}}$ $(\mathcal{l}=e,\ensuremath{\mu})$ and ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}.$ We find sizable renormalization effects from scalar and pseudoscalar four-quark operators in the radiative decays and at $O({\ensuremath{\alpha}}_{s})$ in hadronic b decays. Constraints on the Wilson coefficients of an extended operator basis are worked out. Further, the ratios ${R}_{H}=\mathcal{B}(\stackrel{\ensuremath{\rightarrow}}{B}H{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})/\mathcal{B}(\stackrel{\ensuremath{\rightarrow}}{B}{\mathrm{He}}^{+}{e}^{\ensuremath{-}}),$ for ${H=K}^{(*)}{,X}_{s},$ and their correlations with the ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay are investigated. We show that the standard model prediction for these ratios defined with the same cut on the dilepton mass for electron and muon modes, ${R}_{H}{=1+O(m}_{\ensuremath{\mu}}^{2}{/m}_{b}^{2}),$ has a much smaller theoretical uncertainty $(\ensuremath{\lesssim}1%)$ than the one for the individual branching fractions. The present experimental limit ${R}_{K}l~1.2$ puts constraints on scalar and pseudoscalar couplings, which are similar to the ones from current data on $\mathcal{B}{(B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}).$ We find that new physics corrections to ${R}_{{K}^{*}}$ and ${R}_{{X}_{s}}$ can reach 13% and 10%, respectively.

More model-independent analysis of b→s processes

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.

The Physics of the B Factories

We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, = 2.346+/-0.032+/-0.011 GeV, and - (2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.

K. Bukin

Papers

Branching fraction and photon energy spectrum for b→sγ