456 research outputs found

    Dissecting the ΔI=1/2\Delta I= 1/2 rule at large NcN_c

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    We study the scaling of kaon decay amplitudes with the number of colours, NcN_c, in a theory with four degenerate flavours, Nf=4N_f=4. In this scenario, two current-current operators, Q±Q^\pm, mediate ΔS=1\Delta S=1 transitions, such as the two isospin amplitudes of non-leptonic kaon decays for K→(ππ)I=0,2K\to (\pi\pi)_{I=0,2}, A0A_0 and A2A_2. In particular, we concentrate on the simpler K→πK\to\pi amplitudes, A±A^\pm, mediated by these two operators. A diagrammatic analysis of the large-NcN_c scaling of these observables is presented, which demonstrates the anticorrelation of the leading O(1/Nc){\mathcal O}(1/N_c) and O(Nf/Nc2){\mathcal O}(N_f/N_c^2) corrections in both amplitudes. Using our new Nf=4N_f=4 and previous quenched data, we confirm this expectation and show that these corrections are naturallynaturally large and may be at the origin of the ΔI=1/2\Delta I=1/2 rule. The evidence for the latter is indirect, based on the matching of the amplitudes to their prediction in Chiral Perturbation Theory, from which the LO low-energy couplings of the chiral weak Hamiltonian, g±g^\pm, can be determined. A NLO estimate of the K→(ππ)I=0,2K \to (\pi\pi)_{I=0,2} isospin amplitudes can then be derived, which is in good agreement with the experimental value.Comment: 12 pages, 7 figures. Minor change

    Winding Modes and Large Extra Dimensions

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    We review briefly the main features of the Large Extra Dimensions scenario in the framework of weakly coupled Type I string theory. Kaluza-Klein (KK) excitations of the graviton are expected, whereas no KK modes for the gauge bosons arise if the gauge group is tied to a D3-brane. In this scenario, typical signatures such as direct production of KK modes of the graviton at high-energy colliders could test the size of the compactified dimensions. We point out that contrary to what considered in the literature on the subject, in the general case of anisotropic compactification Winding Modes of the Standard Model gauge bosons could also be directly observable, thus further constraining the model

    Non-alcoholic fatty liver disease connections with fat-free tissues: A focus on bone and skeletal muscle

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    The estimates of global incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) are worrisome, due to the parallel burden of obesity and its metabolic complications. Indeed, excess adiposity and insulin resistance represent two of the major risk factors for NAFLD; interestingly, in the last years a growing body of evidence tended to support a novel mechanistic perspective, in which the liver is at the center of a complex interplay involving organs and systems, other than adipose tissue and glucose homeostasis. Bone and the skeletal muscle are fat- free tissues which appeared to be independently associated with NAFLD in several cross-sectional studies. The deterioration of bone mineral density and lean body mass, leading to osteoporosis and sarcopenia, respectively, are age-related processes. The prevalence of NAFLD also increases with age. Beyond physiological aging, the three conditions share some common underlying mechanisms, and their elucidations could be of paramount importance to design more effective treatment strategies for the management of NAFLD. In this review, we provide an overview on epidemiological data as well as on potential contributors to the connections of NAFLD with bone and skeletal muscle

    Fatty liver index associates with relative sarcopenia and GH/ IGF- 1 status in obese subjects

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    Recently the association between hepatic steatosis and sarcopenia has been described. GH/IGF-1 axis has been postulated to play a role in linking fatty liver and low muscle mass. The aim of our study was to explore the association between fatty liver index, sarcopenic obesity, insulin sensitivity, and GH/IGF-1 status

    Physics and Performance Evaluation Group

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    We summarize the objectives and results of the ``international scoping study of a future neutrino factory and superbeam facility'' (ISS) physics working group. Furthermore, we discuss how the ISS study should develop into a neutrino factory design study (IDS-NF) from the point of view of physics and performance evaluation.Comment: 3 pages, 1 figure. Plenary talk given at the NuFact 07 conferenc

    Gravity-mediated Scalar Dark Matter in Warped Extra-Dimensions

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    We revisit the case of scalar dark matter interacting just gravitationally with the Standard Model (SM) particles in an extra-dimensional Randall-Sundrum scenario. We assume that both, the dark matter and the Standard Model, are localized in the TeV brane and only interact via gravitational mediators, namely the graviton Kaluza-Klein modes and the radion. We analyze in detail the dark matter annihilation channel into two on-shell KK-gravitons, and contrary to previous studies which overlooked this process, we find that it is possible to obtain the correct relic abundance for dark matter masses in the range [1, 10] TeV even after taking into account the strong bounds from LHC Run II. We also consider the impact of the radion contribution (virtual exchange leading to SM final states as well as on-shell production), which does not significantly change our results. Quite interestingly, a sizeable part of the currently allowed parameter space could be tested by LHC Run III and by the High-Luminosity LHC.Comment: 43 pages, 9 figure

    Disability, Physical Inactivity, and Impaired Health-Related Quality of Life Are Not Different in Metabolically Healthy vs. Unhealthy Obese Subjects

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    BACKGROUND: Obesity represents a major health hazard, affecting morbidity, psychological status, physical functionality, quality of life, and mortality. The aim of the present study was to explore the differences between metabolically healthy (MHO) and metabolically unhealthy (MUO) obese subjects with regard to physical activity, disability, and health-related quality of life (HR-QoL). METHODS: All subjects underwent a multidimensional evaluation, encompassing the assessment of body composition, metabolic biomarkers and inflammation, physical activity level (IPAQ questionnaire), disability (TSD-OC test), and HR-QoL (SF-36 questionnaire). MHO and MUO were defined based on the absence or the presence of the metabolic syndrome, respectively. RESULTS: 253 subjects were included (54 men and 199 women; age: 51.7 ± 12.8 vs. 50.3 ± 11.7 years, p = 0.46; BMI: 38.1 ± 5.7 vs. 38.9 ± 6.7 kg/m², p = 0.37). No significant difference was observed in body composition. There was no difference between MHO and MUO considering inflammation (hs-CRP: 6517.1 ± 11,409.9 vs. 5294.1 ± 5612.2 g/L; p = 0.37), physical inactivity (IPAQ score below 3000 METs-min/week in 77.6% of MHO vs. 80% of MUO subjects; p = 0.36), obesity-related disability (TSD-OC score > 33%, indicating a high level of obesity-related disability, in 20.2% of MHO vs. 26.5% of MUO subjects; p = 0.28), and the HR-QoL (SF-36 total score: 60 ± 20.8 vs. 62.8 ± 18.2, p = 0.27). DISCUSSION AND CONCLUSION:The metabolic comorbidity and the impairment of functional ability and psycho-social functioning may have a different timing in the natural history of obesity. Alterations in the physical activity level and mobility disabilities may precede the onset of metabolic abnormalities. (Trial registration 2369 prot 166/12-registered 23 February 2012; Amendment 223/14-registered 13 February 2014)
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