Tests of Factorization and SU(3) Relations in B Decays into Heavy-Light Final States

Using data from the B factories and the Tevatron, we perform tests of how well non-leptonic B decays of the kind B -> D^{(*)}_{(s)} P, where P is a pion or kaon, are described within the factorization framework. We find that factorization works well - as is theoretically expected - for color-allowed, tree-diagram-like topologies. Moreover, also exchange topologies, which have a non-factorizable character, do not show any anomalous behavior. We discuss also isospin triangles between the B -> D^{(*)} pi decay amplitudes, and determine the corresponding amplitudes in the complex plane, which show a significant enhancement of the color-suppressed tree contribution with respect to the factorization picture. Using data for B -> D^{(*)} K decays, we determine SU(3)-breaking effects and cannot resolve any non-factorizable SU(3)-breaking corrections larger than \sim 5%. In view of these results, we point out that a comparison between the \bar B^0_d -> D^+\pi^- and \bar B^0_s -> D_s^+\pi^- decays offers an interesting new determination of f_d/f_s. Using CDF data, we obtain the most precise value of this ratio at CDF, and discuss the prospects for a corresponding measurement at LHCb.Comment: 12 pages, 6 figures, matches published version in Physical Review

A study of rare B-meson decay with muons in the final state with the LHCb detector

The Standard Model (SM) gives a successful description of known phenomena in particle physics, however there are many indications of the existence of New Physics (NP) at the TeV scale. Physicists are building a very large and expensive machine in this belief: the LHC (Large Hadron Collider), which is foreseen to start in the middle 2008. Three of the experiments of the LHC are mainly devoted to the search of NP. Among these, the LHCb experiment is dedicated to the physics of b-hadrons. It will look for indirect evidences of new particles or new degrees of freedom, measuring branching ratios, decay amplitudes and CP asymmetries, which can be sensitive to New Physics effects. Three analysis will be presented: the sensitivity to the $B_{s,d}^0 \rightarrow e^{\pm} \mu^{\mp}$ decays, the sensitivity to the $B_{s,d}^0 \rightarrow \mu^+ \mu^- \gamma$ decays and the correction of angular biases in the $B_d^0 \rightarrow K^{*0} \mu^+ \mu^-$ decay. The $B_{s,d}^0 \rightarrow e^{\pm} \mu^{\mp}$ decays are forbidden in the SM, being lepton flavor violating, but are allowed in some of its extensions. The $90\%$ CL upper bounds that the LHCb experiment can set in $1$ year, running at nominal luminosity, will be presented. These results will be discussed in the context of some Pati-Salam models. The branching ratio of the decays $B_{s,d}^0 \rightarrow \mu^+ \mu^- \gamma$ can be enhanced by NP contributions, such as SUSY contributions. Th e LHCb sensitivity to these decays will be presented. %NP can affect the angular distributions of the B_d^0 \rightarrrow K^{*0} \mu^+ \mu^-. The $A_T^2$ asymmetry in the $B_d^0 \rightarrow K^{*0} \mu^+ \mu^-$ decay is sensitive to NP involving right-handed currents. This asymmetry can be extracted by looking at the angular distributions of the decay products. However this measurement is not straightforward. Two methods for the angular distribution recovering, using the $B_d^{0} \rightarrow J/\psi K^{*0}$ as a control channel, will be presented

Searching for new physics in rare B meson decays

The b → sl+l− transitions are flavour-changing neutral currents, where new physics can enter in competing loop diagrams with respect to the Standard Model contributions. In these decays several observables sensitive to new physics and where theoretical uncertainties are under control can be built. Particularly interesting are the angular asymmetries in the decay Bd → K ∗ μ+μ− and the measurement of the branching ratio of the decays Bs,d → μ+μ−. Recent measurements of these observables and implications for the search of physics beyond the Standard Model will be discussed. Measurements of the isospin asymmetry in the decays B → K(∗)l+l− and the measurement of the branching ratio of the decay B+ → π+μ+μ− will also be discussed

Large-scale impact of Saharan dust on the North Atlantic Ocean circulation

The potential for a dynamical impact of Saharan mineral dust on the North Atlantic Ocean large-scale circulation is investigated. To this end, an ocean general circulation model forced by atmospheric fluxes is perturbed by an idealized, seasonally varying, net shortwave flux anomaly, as it results from remote sensing observations of aerosol optical thickness representing Saharan dust load in the atmosphere. The dust dynamical impact on the circulation is assessed through a comparison between perturbed and an unperturbed run. Results suggest that, following the dust-induced shortwave irradiance anomaly, a buoyancy anomaly is created in the Atlantic offshore the African coast, which over the course of the time propagates westward into the interior Atlantic while progressively subducting. Changes in the large-scale barotropic and overturning circulations are significant after 3 years, which coincides with the elapsed time required by the bulk of the buoyancy perturbation to reach the western boundary of the North Atlantic. Although small in amplitude, the changes in the meridional overturning are of the same order as interannual-to-decadal variability. Variations in the amplitude of the forcing lead to changes in the amplitude of the response, which is almost linear during the first 3 years. In addition, a fast, but dynamically insignificant, response can be observed to propagate poleward along the eastern boundary of the North Atlantic, which contributes to a nonlinear response in the subpolar region north of 40°N