Search

We present an update of the analysis of mixing by the UTfit Collaboration, including the very recent tagged analyses of by the CDF and DØ collaborations. We find that the phase of the mixing amplitude deviates more than 2.9σ from the Standard Model prediction. This results points to extensions of the Standard Model with new sources of CP violation. We compare this result with the analysis of mixing and show that present data favour the presence of a new source of flavour violation. Finally, we consider the impact of this analysis for SUSY models and the possible implications for new physics effects in hadronic penguin decays. [Copyright &y& Elsevier]

We review the status of the unitarity triangle beyond the standard model. First, we discuss the determination of the unitarity triangle in the presence of general loop-mediated new physics and present the constraints on new-physics contributions to amplitudes. Then, we turn to models of minimal flavour violation and present the status of the universal unitarity triangle and the lower bounds on the scale of new physics. Finally, we discuss the impact of the recent measurement of mixing on general SUSY models. [Copyright &y& Elsevier]

In this talk, I briefly review a selection of SUSY effects in B physics. First, I consider models with Minimal Flavour Violation. Then I discuss SUSY models with new sources of flavour violation in squark mass matrices, analyzing present constraints and possible developments with forthcoming data on b → s and b → d transitions. [Copyright &y& Elsevier]

We study the constraints on models with extra dimensions arising from local anomaly cancellation. We consider a five-dimensional field theory with a U(1) gauge field and a charged fermion, compactified on the orbifold S1/(Z2×Z2′). We show that, even if the orbifold projections remove both fermionic zero modes, there are gauge anomalies localized at the fixed points. Anomalies naively cancel after integration over the fifth dimension, but gauge invariance is broken, spoiling the consistency of the theory. We discuss their implications for realistic supersymmetric models with a single Higgs hypermultiplet in the bulk, and possible cancellation mechanisms in non-minimal models.

We analyze the CP violating ratio ε′/εand rare K and B decays in the MSSM with minimal flavour and CP violation, including NLO QCD corrections and imposing constraints on the supersymmetric parameters coming from ε, Bd,s0–B̄d,s0mixings, B→Xsγ, Δϱin the electroweak precision studies and from the lower bound on the neutral Higgs mass. We provide a compendium of phenomenologically relevant formulae in the MSSM. Denoting by T(Q)the MSSM prediction for a given quantity normalized to the Standard Model result we find the ranges: 0.53⩽T(ε′/ε)⩽1.07, 0.65⩽T(K+→π+νν̄)⩽1.02, 0.41⩽T(KL→π0νν̄)⩽1.03, 0.48⩽T(KL→π0e+e−)⩽1.10, 0.73⩽T(B→Xsνν̄)⩽1.34and 0.68⩽T(Bs→μμ̄)⩽1.53. We point out that these ranges will be considerably reduced when the lower bounds on the neutral Higgs mass and tanβimprove. Some contour plots illustrate the dependences of the quantities above on the relevant supersymmetric parameters. As a byproduct of this work we update our previous analysis of ε′/εin the SM and find in NDR ε′/ε=(9.2+6.8−4.0)×10−4, a value 15%higher than in our 1999 analysis.

An upgraded analysis of ?,xd and ?'/?, using the latest determinations of the relevant experimental and theoretical parameters, is presented. Using the recent determination of the top quark mass,mt=(174±17) GeV, our best estimate is ?'/?=(3.1±2.5)×10-, which lies in the range given by E731. We describe our detemination of ?'/? and make a comparison with other similar studies. A detailed discussion of the matching of the full theory to the effective Hamiltonian, written in terms of lattice operators, is also given.

We present upgraded theoretical predictions for inclusive and exclusive radiative decays of Bmesons. Our results include those next-to-leading order corrections that have already been computed. Our best estimates in the Standard Model are BR(B→ K*γ) = (4.3±0.9−1.0+1.4) × 10−5, BR(B→ Xsγ) = (1.9±0.2±0.5) × 10−4, Γ(B→ K*γ)/Γ(B→ Xsγ) = 0.23±0.09 and BR(B→ Xsg) = (1.57±0.15−059+0.86±0.23) × 10−3. We also consider limits found with two-Higgs-doublet models.

The flavour changing top decays t→ cZ0, t→ cgand t→ cγare predicted with invisible rates within the standard model and may represent a window on new physics. We consider these processes in supersymmetric extensions of the standard model and we show that observable rates can be obtained only if the SUSY breaking is non-universal and flavour dependent.

We present the first unquenched lattice QCD results for the bag parameters controlling the short distance contribution to D meson oscillations in the standard model and beyond. We have used the gauge configurations produced by the European Twisted Mass collaboration with Nƒ = 2 dynamical quarks, at four lattice spacings and light meson masses in the range 280-500 MeV. Renormalization is carried out nonperturbatively with the regularization-independent momentum subtraction method. The bag-parameter results have been used to constrain new physics effects in D0 - D0 mixing, to put a lower bound to the generic new physics scale and to constrain off-diagonal squark mass terms for TeV-scale supersymmetry. [ABSTRACT FROM AUTHOR]

Abstract: We present the summer 2012 update of the Unitarity Triangle (UT) analysis performed by the UTfit Collaboration within the Standard Model (SM) and beyond. The increased accuracy on several of the fundamental constraints is now enhancing some of the tensions amongst and within the constraint themselves. In particular, the long standing tension between exclusive and inclusive determinations of the and CKM matrix elements is now playing a major role. Then we present the generalisation the UT analysis to investigate new physics (NP) effects, updating the constraints on NP contributions to processes. In the NP analysis, both CKM and NP parameters are fitted simultaneously to obtain the possible NP effects in any specific sector. Finally, based on the NP constraints, we derive upper bounds on the coefficients of the most general effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of NP that contributes to these low-energy effective interactions. [Copyright &y& Elsevier]

We present the update of the Unitarity Triangle analysis performed by the UT fit Collaboration within the Standard Model and beyond. Within the Standard Model, we find an overall consistency among the constraints, with some tension between the fit prediction and the experimental measurement of , and . Generalising the analysis beyond the Standard Model, we allow for New Physics effects in all processes simultanously. We obtain constraints on the parameters of the Cabibbo-Kobayashi-Maskawa matrix together with the New Physics ones. We find that a deviation from the Standard Model at the 3.1σ level in the mixing phase is confirmed by the present update, which includes the new DØ result on the dimuon charge asymmetry. However the new CDF measurement of is not included yet as the experimental likelihood is not publicly available. [ABSTRACT FROM AUTHOR]

Before the starting of the B factories, the Unitarity Triangle (UT) analysis relied on the results of lattice QCD simulations to relate the experimental determinations of semileptonic B decays, and mixing to the CKM parameters. In the last years, much more information has been obtained from the direct determination of the UT angles from non-leptonic B decays. In this talk, we compare the results of the “classical” UT analysis (UT lattice) with the analysis based on the angles determinations (UT angles). We show that the recent measurement of , combined with and , allows from this comparison a quite accurate extraction of the values of the lattice parameters, , , ξ and . These values, obtained “experimentally” by assuming the validity of the Standard Model, can be compared with the theoretical predictions from lattice QCD. We also discuss the different determinations of and show that current data do not favor the value measured in inclusive decays. Finally, we present updated predictions for the leptonic branching fraction , and compare them with the recent experimental determination. We take the opportunity of this write up to update the results of ref. [M. Bona et al. [UTfit Collaboration], arXiv:hep-ph/0606167] with the most recent results presented at the ICHEP''06 conference. [Copyright &y& Elsevier]