5,411 research outputs found

    Constraints on Natural MNS Parameters from |U_e3|

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    The MNS matrix structure emerging as a result of recent neutrino measurements strongly suggests two large mixing angles (solar and atmospheric) and one small angle (|U_e3| << 1). Especially when combined with the neutrino mass hierarchy, these values turn out to impose rather stringent constraints on possible flavor models connecting the three active fermion generations. Specifically, we show that an extremely small value of |U_e3| would require fine tuning of Majorana mass matrix parameters, particularly in the context of seesaw models.Comment: 21 pages, ReVTeX, 2 .eps figure files, updated references and acknowledgment

    Weak Mixing Angle and Higgs Mass in Gauge-Higgs Unification Models with Brane Kinetic Terms

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    We show that the idea of Gauge-Higgs unification(GHU) can be rescued from the constraint of weak mixing angle by introducing localized brane kinetic terms in higher dimensional GHU models with bulk and simple gauge groups. We find that those terms lead to a ratio between Higgs and W boson masses, which is a little bit deviated from the one derived in the standard model. From numerical analysis, we find that the current lower bound on the Higgs mass tends to prefer to exceptional groups E(6), E(7), E(8) rather than other groups like SU(3l), SO(2n+1), G(2), and F(4) in 6-dimensional(D) GHU models irrespective of the compactification scales. For the compactification scale below 1 TeV, the Higgs masses in 6D GHU models with SU(3l), SO(2n+1), G(2), and F(4) groups are predicted to be less than the current lower bound unless a model parameter responsible for re-scaling SU(2) gauge coupling is taken to be unnaturally large enough. To see how the situation is changed in more higher dimensional GHU model, we take 7D S^{3}/ Z_{2} and 8D T^{4}/ Z_{2} models. It turns out from our numerical analysis that these higher dimensional GHU models with gauge groups except for E(6) can lead to the Higgs boson whose masses are predicted to be above the current lower bound only for the compatification scale above 1 TeV without taking unnaturally large value of the model parameter, whereas the Higgs masses in the GHU models with E(6) are compatible with the current lower bound even for the compatification scale below 1 TeV.Comment: 22 pages, 4 figure

    A prospective cohort study of the effects of adjuvant breast cancer chemotherapy on taste function, food liking, appetite and associated nutritional outcomes

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    \u27Taste\u27 changes are commonly reported during chemotherapy. It is unclear to what extent this relates to actual changes in taste function or to changes in appetite and food liking and how these changes affect dietary intake and nutritional status

    In-situ early age hydration of cement-based materials by synchrotron X-ray powder diffraction

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    Cement based binders are building materials of worldwide importance. Since these samples are very complex, the knowledge/control of their mineralogical composition are essential to design and predict materials with specific/improved performance. Rietveld quantitative phase analysis (RQPA) allows the quantification of crystalline phases and, when combined with specific methodologies, as the addition of an internal standard or the external standard approach (G-factor), amorphous and non-crystalline phases can also be quantified. However, to carry out a proper RQPA in hydrated cementitious-materials, a good powder diffraction pattern is necessary. In this work, synchrotron X-ray powder diffraction (SXRPD) has been used, allowing in-situ measurements during the early-age hydration process. This work deals with the early hydration study of cement-based materials. The studied samples were: a laboratory-prepared belite calcium sulphoaluminate (BCSAF) clinker (non-active) mixed with 10wt% gypsum, labelled G10B0; two active laboratory-prepared BCSAF clinkers (activated with 2wt% borax), one mixed with 10wt% gypsum and the other one with 10wt% monoclinic-bassanite, hereafter named G10B2 and B10B2, respectively; and an environmentally-friendly cement sample from Henkel, composed of bassanite mixed with 15wt% Portland cement and 10wt% Metakaolin, labelled H1. Anhydrous G10B0 contains beta-belite and orthorhombic-ye'elimite as main phases, while alpha'H-belite and pseudo-cubic-ye'elimite are stabilized in G10B2 and B10B2, with the corresponding sulphate source. Anhydrous H1 contains monoclinic and hexagonal bassanite and alite as main phases. Ye'elimite, in the non-active BCSAF cement pastes, dissolves at a higher pace than in the active one (degree of reaction is α~25% and α~10% at 1 h, respectively) (both prepared with gypsum), with the corresponding differences in ettringite crystallisation (degree of precipitation is α~30% and α~5%, respectively). Moreover, the type of sulphate source has important consequences on the hydration of the active BCSAF cement pastes. Bassanite is quickly dissolved and it precipitates as gypsum within the first hour of hydration (in B10B2). At that time, ettringite starts to crystallize, and after 12 hours is almost fully crystallized, similar to G10B2. In H1, bassanite transforms into gypsum within the first hour, being the principal hydration product; ettringite starts to be formed just after few hydration minutes. These results are crucial in the understanding and development of improved cement materials.Universidad de Målaga. Campus de Excelencia Internacional Andalucía Tech

    Supersymmetric Flavor Models and the B --> phi K_S Anomaly

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    We consider the flavor structure of supersymmetric theories that can account for the deviation of the observed time-dependent CP asymmetry in B --> phi K_S from the standard model prediction. Assuming simple flavor symmetries and effective field theory, we investigate possible correlations between sizable supersymmetric contributions to b --> s transitions and to flavor changing processes that are more tightly constrained. With relatively few assumptions, we determine the properties of minimal Yukawa and soft mass textures that are compatible with the desired supersymmetric flavor-changing effect and constraints. We then present explicit models that are designed (at least approximately) to realize these textures. In particular, we present an Abelian model based on a single U(1) factor and a non-trivial extra-dimensional topography that can explain the CP asymmetry in B --> phi K_S, while suppressing other supersymmetric flavor changing effects through a high degree of squark-quark alignment.Comment: 18 pages LaTeX, 3 eps figure

    An A4 flavor model for quarks and leptons in warped geometry

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    We propose a spontaneous A4 flavor symmetry breaking scheme implemented in a warped extra dimensional setup to explain the observed pattern of quark and lepton masses and mixings. The main advantages of this choice are the explanation of fermion mass hierarchies by wave function overlaps, the emergence of tribimaximal neutrino mixing and zero quark mixing at the leading order and the absence of tree-level gauge mediated flavor violations. Quark mixing is induced by the presence of bulk flavons, which allow for cross-brane interactions and a cross-talk between the quark and neutrino sectors, realizing the spontaneous symmetry breaking pattern A4 --> nothing first proposed in [X.G.\,He, Y.Y.\,Keum, R.R.\,Volkas, JHEP{0604}, 039 (2006)]. We show that the observed quark mixing pattern can be explained in a rather economical way, including the CP violating phase, with leading order cross-interactions, while the observed difference between the smallest CKM entries V_{ub} and V_{td} must arise from higher order corrections. We briefly discuss bounds on the Kaluza-Klein scale implied by flavor changing neutral current processes in our model and show that the residual little CP problem is milder than in flavor anarchic models.Comment: 34 pages, 2 figures; version published in JHE

    Limits on excited tau leptons masses from leptonic tau decays

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    We study the effects induced by excited leptons on the leptonic tau decay at one loop level. Using a general effective lagrangian approach to describe the couplings of the excited leptons, we compute their contributions to the leptonic decays and use the current experimental values of the branching ratios to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

    Unprecedented Alexandrium blooms in a previously low biotoxin risk area of Tasmania, Australia.

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    During October 2012, a shipment of blue mussels (Mytilus galloprovincialis) from the poorly monitored east coast of Tasmania, Australia, was tested by Japanese import authorities and found to be contaminated with unacceptable levels of Paralytic Shellfish Toxins (PSTs; 10 mg/kg). Subsequently local oysters, scallops, clams, the viscera of abalone and rock lobsters were also found to be contaminated. This led to a global product recall and loss to the local economy of AUD 23M. Following low toxicity during 2013 and 2014 and implementation of minimal shellfish farm closures, a more severe bloom event occurred during July-November 2015 and again June-September 2016 (up to 300,000 Alexandrium cells/L; 24 mg/kg PST in mussels, 6 mg/kg in Crassostrea gigas oysters), also causing 4 human illnesses resulting in hospitalization after consumption of wild shellfish. While Alexandrium tamarense had been detected in low concentrations in southeastern Australia since 1987, all cultured strains belonged to the mostly non-toxic group 5 (now designated A. australiense; detected since 1987) and weakly toxic group 4 (A. pacificum; detected in 1997). In contrast, the 2012 to 2016 outbreaks were dominated by highly toxic group 1 (A. fundyense) never detected previously in the Australian region. Molecular analyses suggest that A. fundyense may have been a cryptic ribotype previously present in Tasmania, but newly stimulated by altered water column stratification conditions driven by changing rainfall and temperature patterns. Increased seafood and plankton monitoring of the area now include the implementation of Alexandrium qPCR, routine Neogenℱ immunological and HPLC PST tests, but ultimately may also drive change in harvesting strategies and aquaculture species selection by the local seafood industry

    The WHaD diagram: Classifying the ionizing source with one single emission line

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    The usual approach to classify the ionizing source using optical spectroscopy is based on the use of diagnostic diagrams that compares the relative strength of pairs of collisitional metallic lines (e.g., [O iii] and [N ii]) with respect to recombination hydrogen lines (e.g., H{\beta} and H{\alpha}). Despite of being accepted as the standard procedure, it present known problems, including confusion regimes and/or limitations related to the required signal-to-noise of the involved emission lines. These problems affect not only our intrinsic understanding of inter-stellar medium and its poroperties, but also fundamental galaxy properties, such as the star-formation rate and the oxygen abundance, and key questions just as the fraction of active galactic nuclei, among several others. We explore the existing alternatives in the literature to minimize the confusion among different ionizing sources and proposed a new simple diagram that uses the equivalent width and the velocity dispersion from one single emission line, H{\alpha}, to classify the ionizing sources. We use aperture limited and spatial resolved spectroscopic data in the nearby Universe (z{\sim}0.01) to demonstrate that the new diagram, that we called WHaD, segregates the different ionizing sources in a more efficient way that previously adopted procedures. A new set of regions are defined in this diagram to select betweeen different ionizing sources. The new proposed diagram is well placed to determine the ionizing source when only H{\alpha} is available, or when the signal-to-noise of the emission lines involved in the classical diagnostic diagrams (e.g., H{\beta}).Comment: 10 pages, 5 figures, accepted for publishing in A&
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