1,723 research outputs found

    Flavour data constraints on new physics and SuperIso

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    We discuss the implications of B_s -> mu+mu- and B -> K*mu+mu- decays in the context of indirect searches for new physics, emphasising the new LHCb results. In particular, we derive the consequences of the MFV hypothesis and discuss the importance of the MFV predictions. The impact of the recent LHCb measurements in the context of the MSSM will also be addressed, and the SuperIso program will be briefly described.Comment: 7 pages, 4 figures, contribution to the ICHEP 2012 Conference proceedings, 4-11 July 2012, Melbourne, Australi

    On the LHCb anomaly in B -> K* l+ l-

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    The latest LHCb angular analysis of the rare decay B -> K* mu+ mu- shows some discrepancies from the SM up to the 3.7 sigma level. There is a consistent new physics explanation of these anomalies, while it is also reasonable that these anomalies are just statistical fluctuations and/or a direct consequence of underestimated hadronic uncertainties. We briefly discuss possible cross-checks of the various hypotheses with an analysis of the inclusive B -> Xs l+ l- based on the data collected by the B factories Babar and Belle and also based on future opportunities at SuperBelle. We also present a global analysis of the latest LHCb data under the hypothesis of Minimal Flavour Violation. The latter is an important benchmark scenario for new physics models. Any measurements beyond the MFV bounds and relations unambiguously indicate the existence of new flavour structures next to the Yukawa couplings of the Standard Model. However, if new physics is responsible for these discrepancies, we show it is compatible with the MFV hypothesis, so no new flavour structures are needed. Moreover, we analyse the impact of the correlations between the observables based on a Monte Carlo study.Comment: 23 pages, 9 figure

    Signs for new physics in the recent LHCb data?

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    We comment on some tensions with the Standard Model predictions in the recent LHCb data.Comment: 6 pages, 6 figures. Based on talks given at the Fifth Workshop on Theory, Phenomenology and Experiments in Flavour Physics, Capri, 23-25 May 2014 and at the FPCP 2014 conference on Flavor Physics and CP Violation, Marseille, 25-30 May 201

    Global fits to b -> s ll data and signs for lepton non-universality

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    There are some slight tensions with the SM predictions within the latest LHCb measurements. Besides the known anomaly in one angular observable of the rare decay B -> K* mu+ mu-, another small discrepancy recently occurred. The ratio R_K = BR(B+ -> K+ mu+ mu-) / BR(B+ -> K+ e+ e-) in the low-q^2 region has been measured by LHCb showing a 2.6 sigma deviation from the SM prediction. In contrast to the anomaly in the rare decay B -> K* mu+ mu- which is affected by power corrections, the ratio R_K is theoretically rather clean. We analyse all the b -> s ll data with global fits and in particular explore the possibility of breaking of lepton universality. Possible cross-checks with an analysis of the inclusive B -> X_s l+ l- decay are also explored.Comment: 15 pages, 11 figures. v2: references added, to appear in JHE

    On the anomalies in the latest LHCb data

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    Depending on the assumptions on the power corrections to the exclusive b -> s l+ l- decays, the latest data of the LHCb collaboration - based on the 3 fb^-1 data set and on two different experimental analysis methods - still shows some tensions with the SM predictions. We present a detailed analysis of the theoretical inputs and various global fits to all the available b -> s l+ l- data. This constitutes the first global analysis of the new data of the LHCb collaboration based on the hypothesis that these tensions can be at least partially explained by new physics contributions. In our model-independent analysis we present one-, two-, four-, and also five-dimensional global fits in the space of Wilson coefficients to all available b -> s l+ l- data. We also compare the two different experimental LHCb analyses of the angular observables in B -> K* mu+ mu-. We explicitly analyse the dependence of our results on the assumptions about power corrections, but also on the errors present in the form factor calculations. Moreover, based on our new global fits we present predictions for ratios of observables which may show a sign of lepton non-universality. Their measurements would crosscheck the LHCb result on the ratio R_K = BR(B+ -> K+ mu+ mu-) / BR(B+ -> K+ e+ e-) in the low-q^2 region which deviates from the SM prediction by 2.6 sigma.Comment: 41 pages, 24 figures. v2: references and comment on 1006.4945 [hep-ph] adde

    One-loop quantum corrections to cosmological scalar field potentials

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    We study the loop corrections to potentials of complex or coupled real scalar fields used in cosmology to account for dark energy, dark matter or dark fluid. We show that the SUGRA quintessence and dark matter scalar field potentials are stable against the quantum fluctuations, and we propose solutions to the instability of the potentials of coupled quintessence and dark fluid scalar fields. We also find that a coupling to fermions is very restricted, unless this coupling has a structure which already exists in the scalar field potential or which can be compensated by higher order corrections. Finally, we study the influence of the curvature and kinetic term corrections.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.

    A compact representation of the 2 photon 3 gluon amplitude

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    A compact representation of the loop amplitude gamma gamma ggg -> 0 is presented. The result has been obtained by using helicity methods and sorting with respect to an irreducible function basis. We show how to convert spinor representations into a field strength representation of the amplitude. The amplitude defines a background contribution for Higgs boson searches at the LHC in the channel H -> gamma gamma + jet which was earlier extracted indirectly from the one-loop representation of the 5-gluon amplitude.Comment: 15 pages Latex, 6 eps files included, revised versio

    Predictors of sun-protective practices among Iranian female college students: Application of protection motivation theory

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    Purpose: Given the importance of sun protection in the prevention of skin cancer, this study was designed to determine predictors of sun-protective practices among a sample of Iranian female college students based on protection motivation theory (PMT) variables. Materials and Methods: In this cross-sectional study, a total of 201 female college students in Iran University of Medical Sciences were selected. Demographic and PMT variables were assessed with a 67-item questionnaire. Multiple linear regression was used to identify demographic and PMT variables that were associated with sun-protective practices and intention. Results: one percent of participants always wore a hat with a brim, 3.5 gloves and 15.9 sunglasses while outdoors. Only 10.9 regularly had their skin checked by a doctor. Perceived rewards, response efficacy, fear, self-efficacy and marital status were the five variables which could predict 39 variance of participants intention to perform sun-protective practices. Also, intention and response cost explained 31 of the variance of sun-protective practices. Conclusions: These predictive variables may be used to develop theory-based education interventions to prevent skin cancer among college students

    Hydrodynamic instabilities in gaseous detonations: comparison of Euler, Navier–Stokes, and large-eddy simulation

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    A large-eddy simulation is conducted to investigate the transient structure of an unstable detonation wave in two dimensions and the evolution of intrinsic hydrodynamic instabilities. The dependency of the detonation structure on the grid resolution is investigated, and the structures obtained by large-eddy simulation are compared with the predictions from solving the Euler and Navier–Stokes equations directly. The results indicate that to predict irregular detonation structures in agreement with experimental observations the vorticity generation and dissipation in small scale structures should be taken into account. Thus, large-eddy simulation with high grid resolution is required. In a low grid resolution scenario, in which numerical diffusion dominates, the structures obtained by solving the Euler or Navier–Stokes equations and large-eddy simulation are qualitatively similar. When high grid resolution is employed, the detonation structures obtained by solving the Euler or Navier–Stokes equations directly are roughly similar yet equally in disagreement with the experimental results. For high grid resolution, only the large-eddy simulation predicts detonation substructures correctly, a fact that is attributed to the increased dissipation provided by the subgrid scale model. Specific to the investigated configuration, major differences are observed in the occurrence of unreacted gas pockets in the high-resolution Euler and Navier–Stokes computations, which appear to be fully combusted when large-eddy simulation is employed

    The decay Bs -> mu+ mu-: updated SUSY constraints and prospects

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    We perform a study of the impact of the recently released limits on BR(Bs -> mu+ mu-) by LHCb and CMS on several SUSY models. We show that the obtained constraints can be superior to those which are derived from direct searches for SUSY particles in some scenarios, and the use of a double ratio of purely leptonic decays involving Bs -> mu+ mu- can further strengthen such constraints. We also discuss the experimental sensitivity and prospects for observation of Bs -> mu+ mu- during the sqrt(s)=7 TeV run of the LHC, and its potential implications.Comment: 30 pages, 21 figures. v2: Improved discussion of constraints from B -> tau nu, references adde
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