63 research outputs found
Measurement of the isospin asymmetry in B -> K(*) mu+mu- decays
No full textThe isospin asymmetries of B → K (∗) μ + μ − decays and the partial branching fractions of B 0 → K 0 μ + μ − and B + → K ∗+ μ + μ − are measured as a function of the di-muon mass squared q 2 using an integrated luminosity of 1.0 fb−1 collected with the LHCb detector. The B → Kμ + μ − isospin asymmetry integrated over q 2 is negative, deviating from zero with over 4 σ significance. The B → K ∗ μ + μ − decay measurements are consistent with the Standard Model prediction of negligible isospin asymmetry. The observation of the decay B 0 → K S μ + μ − is reported with 5.7 σ significance. Assuming that the branching fraction of B 0 → K 0 μ + μ − is twice that of B 0 → K S μ + μ −, the branching fractions of B 0 → K 0 μ + μ − and B → K ∗+ μ + μ − are found to be (0.31−0.06) × 10−6 and (1.16 ± 0.19) × 10−6, respectively
Differential branching fraction and angular analysis of the decay → ϕμ + μ −
No full textThe determination of the differential branching fraction and the first angular analysis of the decay B0s → ϕμ + μ − are presented using data, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment at s√=7 TeV. The differential branching fraction is determined in bins of q 2, the invariant dimuon mass squared. Integration over the full q 2 range yields a total branching fraction of B(B0s→ϕμ+μ−)=(7.07+0.64−0.59±0.71±0.71) × 10−7, where the first uncertainty is statistical, the second systematic, and the third originates from the branching fraction of the normalisation channel. An angular analysis is performed to determine the angular observables F L, S 3, A 6, and A 9. The observables are consistent with Standard Model expectations
Measurement of the D-s+-D-s- production asymmetry in 7 TeV pp collisions
No full textHeavy quark production in 7 TeV centre-of-mass energy pp collisions at the LHC is not necessarily flavour symmetric. The production asymmetry, AP, between and mesons is studied using the ϕπ± decay mode in a data sample of 1.0 fb−1 collected with the LHCb detector. The difference between π+ and π− detection efficiencies is determined using the ratios of fully reconstructed to partially reconstructed D⁎± decays. The overall production asymmetry in the rapidity region 2.0 to 4.5 with transverse momentum larger than 2 GeV is measured to be AP=(−0.33±0.22±0.10)%. This result can constrain models of heavy flavour production
On new physics in Delta Gamma(d)
No full textMotivated by the recent measurement of the dimuon asymmetry by the DØ collaboration, which could be interpreted as an enhanced decay rate difference in the neutral B d -meson system, we investigate the possible size of new-physics contributions to ΔΓ d . In particular, we perform model-independent studies of non-standard effects associated to the dimension-six current-current operators (d̄p) (p̄′b) with p, -rfpag′ = u, c as well as (d̄p) (τ̄τ). In both cases we find that for certain flavour or Lorentz structures of the operators sizeable deviations of ΔΓ d away from the Standard Model expectation cannot be excluded in a model-independent fashion. © 2014 The Author(s)
From childhood nature experiences to adult pro-environmental behaviors : An explanatory model of sustainable food consumption
No full textIn two studies, the role of nature experiences and social norms during childhood is explored next to adulthood biospheric values, connectedness to nature, environmental identity, and objective knowledge in relation to pro-environmental behaviors. Study 1 (N = 185) tested the hypothesized model in the realm of general pro-environmental behaviors and sustainable fruit consumption on a sample of students. Study 2 (N = 155) tested the model in the realm of sustainable seafood consumer choice on a general population sample. Path analyses show consistent results across samples. Results show that childhood nature experiences and exposure to pro-environmental social norms during childhood are related to adulthood development of connectedness with nature and biospheric values; these, in turn, help in shaping adulthood environmental self-identity ultimately influencing the enactment of sustainable food choices during adulthood. These findings point toward the relevance of childhood experiences for pro-environmental behaviors as compared to the provision of information. The role of objective knowledge across samples is inconsistent, thus requiring future investigations
Effective field theory approach to QED corrections in flavour physics
No full textThanks to the accurate measurements performed at the low-energy facilities [1] and LHC, flavour physics of light quarks, especially the bottom quark, emerged on the precision frontier for tests of the standard model (SM) and in searches for new physics effects. On the theoretical side, short-distance perturbative higher-order QCD and electroweak corrections are under good control for many processes. Moreover, tremendous progress in lattice computations [2] allows achieving percent to even subpercent accuracy for long-distance nonperturbative quantities. This allows for the prediction of some key observables with unprecedented accuracy and in turn the determination of short-distance parameters like the elements of the quark-mixing matrix (CKM) in the framework of the SM. In view of these prospects, it is also desirable to improve the understanding and treatment of QED corrections, which are generally assumed to be small. Unfortunately not much new development has taken place in the evaluation of such corrections
Morphological transition in Ni/C nanoscale multilayers
No full textS.279-284Annealing of nanoscale Ni/C multilayers and C/Ni/C trilayers at temperatures above about 670 K leads to the formation of separated Ni particles embedded in carbon. The agglomeration of the Ni layers starts by the formation of holes in the Ni layer and proceeds by hole growth and hole coalescence. Different thermodynamic driving forces and kinetic processes which can affect the observed agglomeration are discussed. The formation of holes by thermal grooving of Ni grain boundaries is analyzed quantitatively
EOS: a software for flavor physics phenomenology
No full textEOS is an open-source software for a variety of computational tasks in flavor physics. Its use cases include theory predictions within and beyond the Standard Model of particle physics, Bayesian inference of theory parameters from experimental and theoretical likelihoods, and simulation of pseudo events for a number of signal processes. EOS ensures high-performance computations through a C++ back-end and ease of usability through a Python front-end. To achieve this flexibility, EOS enables the user to select from a variety of implementations of the relevant decay processes and hadronic matrix elements at run time. In this article, we describe the general structure of the software framework and provide basic examples. Further details and in-depth interactive examples are provided as part of the EOS online documentation
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