Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian

Employing background-field method and super-heat-kernel expansion, we compute the complete one-loop renormalization of the electroweak chiral Lagrangian with a light Higgs boson. Earlier results from purely scalar fluctuations are confirmed as a special case. We also recover the one-loop renormalization of the conventional Standard Model in the appropriate limit.Comment: 15 pages, no figures; v2: reference and comments added, typos fixed, matches published versio

QCD Factorization for B→ππB\to\pi\pi Decays: Strong Phases and CP Violation in the Heavy Quark Limit

We show that, in the heavy quark limit, the hadronic matrix elements that enter $B$ meson decays into two light mesons can be computed from first principles, including `non-factorizable' strong interaction corrections, and expressed in terms of form factors and meson light-cone distribution amplitudes. The conventional factorization result follows in the limit when both power corrections in $1/m_b$ and radiative corrections in $\alpha_s$ are neglected. We compute the order-$\alpha_s$ corrections to the decays $B_d\to\pi^+\pi^-$, $B_d\to\pi^0\pi^0$ and $B^+\to\pi^+\pi^0$ in the heavy quark limit and briefly discuss the phenomenological implications for the branching ratios, strong phases and CP violation.Comment: 6 pages, 1 figur

Two-Loop Large-mtm_t Electroweak Corrections to K→πννˉK\to\pi\nu\bar\nu for Arbitrary Higgs Boson Mass

We consider for the first time the leading large top mass corrections, arising at higher order in electroweak interactions, to the rare decays $K\to\pi\nu\bar\nu$ and the related modes $B\to X_s\nu\bar\nu$ and $B\to l^+l^-$. Higher order effects of similar type have previously been calculated in the large-$m_t$ limit for key observables of precision electroweak physics at Z-factories. Here we obtain the corresponding corrections of order ${\cal O}(G^2_F m^4_t)$ at the amplitude level for short-distance dominated rare meson decays. This allows us to quantify the importance of higher order electroweak effects for these processes, which can be reliably computed and have very small uncertainties from strong interactions. Simultaneously it becomes possible to remove, to some extent, ambiguities in the definition of electroweak parameters describing the strength of FCNC interactions. The corrections we discuss are at the level of a few percent.Comment: 11 pages, LaTeX, 1 eps-figur

Next-to-Leading Order QCD Corrections to the Lifetime Difference of BsB_s Mesons

We compute the QCD corrections to the decay rate difference in the $B_s-\bar B_s$ system, $\Delta\Gamma_{B_s}$, in the next-to-leading logarithmic approximation using the heavy quark expansion approach. Going beyond leading order in QCD is essential to obtain a proper matching of the Wilson coefficients to the matrix elements of local operators from lattice gauge theory. The lifetime difference is reduced considerably at next-to-leading order. We find $(\Delta\Gamma/\Gamma)_{B_s}=(f_{B_s}/210 MeV)^2 [0.006 B(m_b)+0.150 B_S(m_b)-0.063]$ in terms of the bag parameters $B, B_S$ in the NDR scheme. As a further application of our analysis we also derive the next-to-leading order result for the mixing-induced CP asymmetry in inclusive $b\to u\bar ud$ decays, which measures $\sin 2\alpha$.Comment: 14 pages, LaTeX, 1 figure; minor modifications of the text, improved discussion of eq. (35), all results unchange

New Physics Effects in B→K(∗)ννB \to K^(*) \nu \nu Decays

We present a model-independent analysis of rare B decays, $B \to K^{(*)} \nu \nu$. The effect of possible new physics is written in terms of dimension-6 four-fermi interactions. The lepton number violating scalar- and tensor-type interactions are included, and they induce $B \to K^{(*)} \nu \nu ({\bar \nu} {\bar \nu})$ decays. We show systematically how the branching ratios and missing mass-squared spectrum depend on the coefficients of the four-fermi interactions.Comment: 20 pages with 7 figure

Long distance contribution to K+→π+ννˉK^+ \to \pi^+ \nu {\bar \nu} decay and O(p4)O(p^4) terms in CHPT

The long distance contribution to $K^+ \to \pi^+ \nu {\bar \nu}$ is calculated using chiral perturbation theory. The leading contribution comes from $O(p^4)$ tree terms. The branching ratio of the $O(p^4)$ long distance contribution is found to be of order $10_{-3}$ smaller than the short distance contributions.Comment: 12 pages, 1 figure (available upon request

On the Standard Model prediction for BR(B{s,d} to mu+ mu-)

The decay Bs to mu+ mu- is one of the milestones of the flavor program at the LHC. We reappraise its Standard Model prediction. First, by analyzing the theoretical rate in the light of its main parametric dependence, we highlight the importance of a complete evaluation of higher-order electroweak corrections, at present known only in the large-mt limit, and leaving sizable dependence on the definition of electroweak parameters. Using insights from a complete calculation of such corrections for K to pi bar{nu} nu decays, we find a scheme in which NLO electroweak corrections are likely to be negligible. Second, we address the issue of the correspondence between the initial and the final state detected by the experiments, and those used in the theoretical prediction. Particular attention is devoted to the effect of the soft radiation, that has not been discussed for this mode in the previous literature, and that can lead to O(10%) corrections to the decay rate. The "non-radiative" branching ratio (that is equivalent to the branching ratio fully inclusive of bremsstrahlung radiation) is estimated to be (3.23 +/- 0.27) x 10^{-9} for the flavor eigenstate, with the main uncertainty resulting from the value of f_{Bs}, followed by the uncertainty due to higher order electroweak corrections. Applying the same strategy to Bd to mu+ mu-, we find for its non-radiative branching ratio (1.07 +/- 0.10) x 10^{-10}.Comment: 15 pages. v3: very minor changes to match the journal version (EPJC

QCD factorization for exclusive, non-leptonic B meson decays: General arguments and the case of heavy-light final states

We provide a rigorous basis for factorization for a large class of non-leptonic two-body $B$-meson decays in the heavy-quark limit. The factorization formula incorporates elements of the naive factorization approach and the hard-scattering approach, but allows us to compute systematically radiative (``non-factorizable'') corrections to naive factorization for decays such as $B\to D\pi$ and $B\to \pi \pi$. We discuss the factorization formula for a general final state from a general point of view. We then consider factorization for decays into heavy-light final states (such as $B\to D\pi$) in more detail, including a proof of the factorization formula at two-loop order. Explicit results for the leading QCD corrections to factorization are presented and compared to existing measurements of branching fractions and final-state interaction phases

Estimate of B(K -> pi nu nubar) from Standard Model fits to lambda_t

We estimate B(K -> pi nu nubar) in the context of the Standard Model by fitting for lambda_t = Vtd x V*ts of the `kaon unitarity triangle' relation. We fit data from epsilon_K, the CP-violating parameter describing K-mixing, and a_{psi K}, the CP-violating asymmetry in B -> J/psi K decays. Our estimate is independent of the CKM matrix element Vcb and of the ratio of Bs to Bd mixing frequencies. The measured value of B(K+ -> pi+ nu nubar) can be compared both to this estimate and to predictions made from the ratio of B mixing frequencies.Comment: 8 pages, including 6 figures. v3 includes an expanded discussion of correlations between SM inputs to the lambda_t fit, clarifies the discussion of the independence of this result from the ratio of B mixing frequencies, includes minor updates to the values of SM input parameters, and includes some new and some updated reference