48,626 research outputs found

    Determination of the Heat Resistance of Microbial Isolates from EASL

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    Dry heat resistance of bacterial spores from sterilization and assembly laborator

    RK()R_{K^{(*)}} with leptoquarks and the origin of Yukawa couplings

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    We construct a model where the Yukawa couplings of the Standard Model (SM) fermions arise from the breaking of a Z2Z_2 symmetry and through mixing with a fourth family of vector-like fermions. By adding a scalar leptoquark, which is an electroweak triplet and odd under the Z2Z_2 symmetry, we obtain an explanation for RK()R_{K^{(*)}} that is linked to the origin of the Yukawa couplings. The coupling of SM fermions to the leptoquark is mediated by the fourth family fermions, and is predicted to be related to CKM entries and mass ratios of SM fermions.Comment: 17 pages, 2 figures. Version accepted for publication in JHE

    An S4×SU(5)S_4 \times SU(5) SUSY GUT of flavour in 6d

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    We propose a 6d model with a SUSY SU(5)SU(5) gauge symmetry. After compactification, it explains the origin of the S4S_4 Family Symmetry with CSD3 vacuum alignment, as well as SU(5)SU(5) breaking with doublet-triplet splitting. The model naturally accounts for all quark and lepton (including neutrino) masses and mixings, incorporating the highly predictive Littlest Seesaw structure. It spontaneously breaks CP symmetry, resulting in successful CP violation in the quark and lepton sectors, while solving the Strong CP problem. It also explains the Baryon Asymmetry of the Universe (BAU) through leptogenesis, with the leptogenesis phase directly linked to the Dirac and Majorana phases.Comment: 23 pages, 6 figures. v3: Version published in JHE

    SU(3) family symmetry and neutrino bi-tri-maximal mixing

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    The observed large mixing angles in the lepton sector may be the first signal for the presence of a non-Abelian family symmetry. However, to obtain the significant differences between the mixing of the neutrino and charged fermion sectors, the vacuum expectation values involved in the breaking of such a symmetry in the two sectors must be misaligned. We investigate how this can be achieved in models with an SU(3) family symmetry consistent with an underlying GUT. We show that such misalignment can be achieved naturally via the see-saw mechanism. We construct a specific example in which the vacuum (mis)alignment is guaranteed by additional symmetries. This model generates a fermion mass structure consistent with all quark and lepton masses and mixing angles. Neutrino mixing is close to bi-tri-maximal mixing.Comment: References added; typos correcte

    Representation of probabilistic scientific knowledge

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    This article is available through the Brunel Open Access Publishing Fund. Copyright © 2013 Soldatova et al; licensee BioMed Central Ltd.The theory of probability is widely used in biomedical research for data analysis and modelling. In previous work the probabilities of the research hypotheses have been recorded as experimental metadata. The ontology HELO is designed to support probabilistic reasoning, and provides semantic descriptors for reporting on research that involves operations with probabilities. HELO explicitly links research statements such as hypotheses, models, laws, conclusions, etc. to the associated probabilities of these statements being true. HELO enables the explicit semantic representation and accurate recording of probabilities in hypotheses, as well as the inference methods used to generate and update those hypotheses. We demonstrate the utility of HELO on three worked examples: changes in the probability of the hypothesis that sirtuins regulate human life span; changes in the probability of hypotheses about gene functions in the S. cerevisiae aromatic amino acid pathway; and the use of active learning in drug design (quantitative structure activity relation learning), where a strategy for the selection of compounds with the highest probability of improving on the best known compound was used. HELO is open source and available at https://github.com/larisa-soldatova/HELO.This work was partially supported by grant BB/F008228/1 from the UK Biotechnology & Biological Sciences Research Council, from the European Commission under the FP7 Collaborative Programme, UNICELLSYS, KU Leuven GOA/08/008 and ERC Starting Grant 240186

    SO(10)×S4\mathbf{SO(10)}\times \mathbf{S_4} Grand Unified Theory of Flavour and Leptogenesis

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    We propose a Grand Unified Theory of Flavour, based on SO(10)SO(10) together with a non-Abelian discrete group S4S_4, under which the unified three quark and lepton 16-plets are unified into a single triplet 33'. The model involves a further discrete group Z4R×Z43 \mathbb{Z}_4^R\times \mathbb{Z}_4^3 which controls the Higgs and flavon symmetry breaking sectors. The CSD2 flavon vacuum alignment is discussed, along with the GUT breaking potential and the doublet-triplet splitting, and proton decay is shown to be under control. The Yukawa matrices are derived in detail, from renormalisable diagrams, and neutrino masses emerge from the type I seesaw mechanism. A full numerical fit is performed with 15 input parameters generating 19 presently constrained observables, taking into account supersymmetry threshold corrections. The model predicts a normal neutrino mass ordering with a CP oscillation phase of 260260^{\circ}, an atmospheric angle in the first octant and neutrinoless double beta decay with mββ=11m_{\beta \beta}= 11 meV. We discuss N2N_2 leptogenesis, which fixes the second right-handed neutrino mass to be M22×1011M_2\simeq 2\times 10^{11} GeV, in the natural range predicted by the model.Comment: 26 pages, 10 figure
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