M. Bona

Model-independent constraints on ΔF = 2 operators and the scale of new physics

We update the constraints on new-physics contributions to ΔF = 2 processes from the generalized unitarity triangle analysis, including the most recent experimental developments. Based on these constraints, we derive upper bounds on the coefficients of the most general ΔF = 2 effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of new physics that contributes to these low-energy effective interactions. We point out that, due to the enhancement in the renormalization group evolution and in the matrix elements, the coefficients of non-standard operators are much more constrained than the coefficient of the operator present in the Standard Model. Therefore, the scale of new physics in models that generate new ΔF = 2 operators, such as next-to-minimal flavour violation, has to be much higher than the scale of minimal flavour violation, and it most probably lies beyond the reach of direct searches at the LHC.

The unitarity triangle fit in the standard model and hadronic parameters from lattice QCD: a reappraisal after the measurements of Δms and BR(B→τντ)

The recent measurements of the B0s meson mixing amplitude by CDF and of the leptonic branching fraction BR(B→τντ) by Belle call for an upgraded analysis of the Unitarity Triangle in the Standard Model. Besides improving the previous constraints on the parameters of the CKM matrix, these new measurements, combined with the recent determinations of the angles α, β and γ from non-leptonic decays, allow, in the Standard Model, a quite accurate extraction of the values of the hadronic matrix elements relevant for K0-0 and Bs,d0-s,d0 mixing and of the leptonic decay constant fB. In this paper we upgrade the UT fit, we determine from the data the kaon B-parameter K, the B0 mixing amplitude parameters fBs 1/2Bs and ξ, the decay constant fB, and make a comparison of the obtained values with lattice predictions. We also discuss the different determinations of Vub and show that current data do not favour the value measured in inclusive decays.

SuperB: A High-Luminosity Asymmetric e+e- Super Flavor Factory

The physics objectives of SuperB, an asymmetric electron-positron collider with a luminosity above 10^36/cm^2/s are described, together with the conceptual design of a novel low emittance design that achieves this performance with wallplug power comparable to that of the current B Factories, and an upgraded detector capable of doing the physics in the SuperB environment.

Constraints on new physics from the quark mixing unitarity triangle.

The status of the unitary triangle beyond the standard model including the most recent results on Deltam[s] on dilepton asymmetries and on width differences is presented. Even allowing for general new physics loop contributions the unitarity triangle must be very close to the standard model result. With the new measurements from the Fermilab Tevatron, we obtain for the first time a significant constraint on new physics in the Bs sector. We present the allowed ranges of new physics contributions to DeltaF=2 processes and of the time-dependent CP asymmetry in Bs-->J/psivarphi decays.

Improved Determination of the CKM Angle alpha from B to pi pi decays

Motivated by a recent paper that compares the results of the analysis of the CKM angle alpha in the frequentist and in the Bayesian approaches, we have reconsidered the information on the hadronic amplitudes, which helps constraining the value of alpha in the Standard Model. We find that the Bayesian method gives consistent results irrespective of the parametrisation of the hadronic amplitudes and that the results of the frequentist and Bayesian approaches are equivalent when comparing meaningful probability ranges or confidence levels. We also find that from B to pi pi decays alone the 95% probability region for alpha is the interval [80^o,170^o], well consistent with recent analyses of the unitarity triangle where, by using all the available experimental and theoretical information, one gets alpha = (93 +- 4)^o. Last but not least, by using simple arguments on the hadronic matrix elements, we show that the unphysical region alpha ~ 0, present in several experimental analyses, can be eliminated.

Status of the Cabibbo-Kobayashi-Maskawa matrix and Unitarity Triangle fits

The status of the Unitarity Triangle analysis realized by the UTfit Collaboration is presented. The most recent determinations of theoretical and experimental parameters are used in order to over-constrain the apex of the Unitarity Triangle in the Standard Model. In addition, we present the analysis of the Unitarity Triangle beyond the Standard Model, by parametrizing New Physics contributions in DeltaF = 2 processes. With the new measurements from the Tevatron, namely the mass difference Delta m_s, the width difference Delta Gammas and the di-muon asymmetry, it is possible to establish significant bounds on New Physics parameters also in the B_s sector. The results and the plots presented in this paper can be found at the URL httpwwwutfit.org, where they are continuously kept up-to-date.