1,330 research outputs found

    Gravity waves and the LHC: Towards high-scale inflation with low-energy SUSY

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    It has been argued that rather generic features of string-inspired inflationary theories with low-energy supersymmetry (SUSY) make it difficult to achieve inflation with a Hubble scale H > m_{3/2}, where m_{3/2} is the gravitino mass in the SUSY-breaking vacuum state. We present a class of string-inspired supergravity realizations of chaotic inflation where a simple, dynamical mechanism yields hierarchically small scales of post-inflationary supersymmetry breaking. Within these toy models we can easily achieve small ratios between m_{3/2} and the Hubble scale of inflation. This is possible because the expectation value of the superpotential relaxes from large to small values during the course of inflation. However, our toy models do not provide a reasonable fit to cosmological data if one sets the SUSY-breaking scale to m_{3/2} < TeV. Our work is a small step towards relieving the apparent tension between high-scale inflation and low-scale supersymmetry breaking in string compactifications.Comment: 21+1 pages, 5 figures, LaTeX, v2: added references, v3: very minor changes, version to appear in JHE

    Anomalous Dimensions and Non-Gaussianity

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    We analyze the signatures of inflationary models that are coupled to strongly interacting field theories, a basic class of multifield models also motivated by their role in providing dynamically small scales. Near the squeezed limit of the bispectrum, we find a simple scaling behavior determined by operator dimensions, which are constrained by the appropriate unitarity bounds. Specifically, we analyze two simple and calculable classes of examples: conformal field theories (CFTs), and large-N CFTs deformed by relevant time-dependent double-trace operators. Together these two classes of examples exhibit a wide range of scalings and shapes of the bispectrum, including nearly equilateral, orthogonal and local non-Gaussianity in different regimes. Along the way, we compare and contrast the shape and amplitude with previous results on weakly coupled fields coupled to inflation. This signature provides a precision test for strongly coupled sectors coupled to inflation via irrelevant operators suppressed by a high mass scale up to 1000 times the inflationary Hubble scale.Comment: 40 pages, 10 figure

    A Terminal Velocity on the Landscape: Particle Production near Extra Species Loci in Higher Dimensions

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    We investigate particle production near extra species loci (ESL) in a higher dimensional field space and derive a speed limit in moduli space at weak coupling. This terminal velocity is set by the characteristic ESL-separation and the coupling of the extra degrees of freedom to the moduli, but it is independent of the moduli's potential if the dimensionality of the field space is considerably larger than the dimensionality of the loci, D >> d. Once the terminal velocity is approached, particles are produced at a plethora of nearby ESLs, preventing a further increase in speed via their backreaction. It is possible to drive inflation at the terminal velocity, providing a generalization of trapped inflation with attractive features: we find that more than sixty e-folds of inflation for sub-Planckian excursions in field space are possible if ESLs are ubiquitous, without fine tuning of initial conditions and less tuned potentials. We construct a simple, observationally viable model with a slightly red scalar power-spectrum and suppressed gravitational waves; we comment on the presence of additional observational signatures originating from IR-cascading and individual massive particles. We also show that moduli-trapping at an ESL is suppressed for D >> d, hindering dynamical selection of high-symmetry vacua on the landscape based on this mechanism.Comment: 46 pages, 6 figures. V3: typos corrected compared to JHEP version, conclusions unchange

    Desensitizing Inflation from the Planck Scale

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    A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale effects, which is a rather strong requirement on possible ultraviolet completions of the theory. In this paper, we show that the breaking of the shift symmetry by Planck-scale corrections can be systematically suppressed if the inflaton field interacts with a conformal sector. The inflaton then receives an anomalous dimension in the conformal field theory, which leads to sequestering of all dangerous high-energy corrections. We analyze a number of models where the mechanism can be seen in action. In our most detailed example we compute the exact anomalous dimensions via a-maximization and show that the eta problem can be solved using only weakly-coupled physics.Comment: 34 pages, 3 figures

    Kahler Moduli Inflation Revisited

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    We perform a detailed numerical analysis of inflationary solutions in Kahler moduli of type IIB flux compactifications. We show that there are inflationary solutions even when all the fields play an important role in the overall shape of the scalar potential. Moreover, there exists a direction of attraction for the inflationary trajectories that correspond to the constant volume direction. This basin of attraction enables the system to have an island of stability in the set of initial conditions. We provide explicit examples of these trajectories, compute the corresponding tilt of the density perturbations power spectrum and show that they provide a robust prediction of n_s approximately 0.96 for 60 e-folds of inflation.Comment: 27 pages, 9 figure

    Multifield Dynamics in Higgs-otic Inflation

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    In Higgs-otic inflation a complex neutral scalar combination of the h0h^0 and H0H^0 MSSM Higgs fields plays the role of inflaton in a chaotic fashion. The potential is protected from large trans-Planckian corrections at large inflaton if the system is embedded in string theory so that the Higgs fields parametrize a D-brane position. The inflaton potential is then given by a DBI+CS D-brane action yielding an approximate linear behaviour at large field. The inflaton scalar potential is a 2-field model with specific non-canonical kinetic terms. Previous computations of the cosmological parameters (i.e. scalar and tensor perturbations) did not take into account the full 2-field character of the model, ignoring in particular the presence of isocurvature perturbations and their coupling to the adiabatic modes. It is well known that for generic 2-field potentials such effects may significantly alter the observational signatures of a given model. We perform a full analysis of adiabatic and isocurvature perturbations in the Higgs-otic 2-field model. We show that the predictivity of the model is increased compared to the adiabatic approximation. Isocurvature perturbations moderately feed back into adiabatic fluctuations. However, the isocurvature component is exponentially damped by the end of inflation. The tensor to scalar ratio varies in a region r=0.08−0.12r=0.08-0.12, consistent with combined Planck/BICEP results.Comment: 35 pages, 11 figure

    Dental management considerations for the patient with an acquired coagulopathy. Part 1: Coagulopathies from systemic disease

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    Current teaching suggests that many patients are at risk for prolonged bleeding during and following invasive dental procedures, due to an acquired coagulopathy from systemic disease and/or from medications. However, treatment standards for these patients often are the result of long-standing dogma with little or no scientific basis. The medical history is critical for the identification of patients potentially at risk for prolonged bleeding from dental treatment. Some time-honoured laboratory tests have little or no use in community dental practice. Loss of functioning hepatic, renal, or bone marrow tissue predisposes to acquired coagulopathies through different mechanisms, but the relationship to oral haemostasis is poorly understood. Given the lack of established, science-based standards, proper dental management requires an understanding of certain principles of pathophysiology for these medical conditions and a few standard laboratory tests. Making changes in anticoagulant drug regimens are often unwarranted and/or expensive, and can put patients at far greater risk for morbidity and mortality than the unlikely outcome of postoperative bleeding. It should be recognised that prolonged bleeding is a rare event following invasive dental procedures, and therefore the vast majority of patients with suspected acquired coagulopathies are best managed in the community practice setting

    Long-term retention on treatment with lumiracoxib 100 mg once or twice daily compared with celecoxib 200 mg once daily: A randomised controlled trial in patients with osteoarthritis

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    BACKGROUND: The efficacy, safety and tolerability of lumiracoxib, a novel selective cyclooxygenase-2 (COX-2) inhibitor, has been demonstrated in previous studies of patients with osteoarthritis (OA). As it is important to establish the long-term safety and efficacy of treatments for a chronic disease such as OA, the present study compared the effects of lumiracoxib at doses of 100 mg once daily (o.d.) and 100 mg twice daily (b.i.d.) with those of celecoxib 200 mg o.d. on retention on treatment over 1 year. METHODS: In this 52-week, multicentre, randomised, double-blind, parallel-group study, male and female patients (aged at least 40 years) with symptomatic primary OA of the hip, knee, hand or spine were randomised (1:2:1) to lumiracoxib 100 mg o.d. (n = 755), lumiracoxib 100 mg b.i.d. (n = 1,519) or celecoxib 200 mg o.d. (n = 758). The primary objective of the study was to demonstrate non-inferiority of lumiracoxib at either dose compared with celecoxib 200 mg o.d. with respect to the 1-year retention on treatment rate. Secondary outcome variables included OA pain in the target joint, patient's and physician's global assessments of disease activity, Short Arthritis assessment Scale (SAS) total score, rescue medication use, and safety and tolerability. RESULTS: Retention rates at 1 year were similar for the lumiracoxib 100 mg o.d., lumiracoxib 100 mg b.i.d. and celecoxib 200 mg o.d. groups (46.9% vs 47.5% vs 45.3%, respectively). It was demonstrated that retention on treatment with lumiracoxib at either dose was non-inferior to celecoxib 200 mg o.d. Similarly, Kaplan-Meier curves for the probability of premature discontinuation from the study for any reason were similar across the treatment groups. All three treatments generally yielded comparable results for the secondary efficacy variables and all treatments were well tolerated. CONCLUSION: Long-term treatment with lumiracoxib 100 mg o.d., the recommended dose for OA, was as effective and well tolerated as celecoxib 200 mg o.d. in patients with OA. TRIAL REGISTRATION: clinicaltrials.gov NCT00145301

    Brane-World Gravity

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    The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the \textit{d} extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∟\sim TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004) "Brane-World Gravity", 119 pages, 28 figures, the update contains new material on RS perturbations, including full numerical solutions of gravitational waves and scalar perturbations, on DGP models, and also on 6D models. A published version in Living Reviews in Relativit

    Immunohistochemical expression of insulin-like growth factor binding protein-3 in invasive breast cancers and ductal carcinoma in situ: implications for clinicopathology and patient outcome

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    INTRODUCTION: Insulin-like growth factor binding protein-3 (IGFBP-3) differentially modulates breast epithelial cell growth through insulin-like growth factor (IGF)-dependent and IGF-independent pathways and is a direct (IGF-independent) growth inhibitor as well as a mitogen that potentiates EGF (epidermal growth factor) and interacts with HER-2. Previously, high IGFBP-3 levels in breast cancers have been determined by enzyme-linked immunosorbent assay and immunoradiometric assay methods. In vitro, IGFBP-3's mechanisms of action may involve cell membrane binding and nuclear translocation. To evaluate tumour-specific IGFBP-3 expression and its subcellular localisation, this study examined immunohistochemical IGFBP-3 expression in a series of invasive ductal breast cancers (IDCs) with synchronous ductal carcinomas in situ (DCIS) in relation to clinicopathological variables and patient outcome. METHODS: Immunohistochemical expression of IGFBP-3 was evaluated with the sheep polyclonal antiserum (developed in house) with staining performed as described previously. RESULTS: IGFBP-3 was evaluable in 101 patients with a variable pattern of cytoplasmic expression (positivity of 1+/2+ score) in 85% of invasive and 90% of DCIS components. Strong (2+) IGFBP-3 expression was evident in 32 IDCs and 40 cases of DCIS. A minority of invasive tumours (15%) and DCIS (10%) lacked IGFBP-3 expression. Nuclear IGFBP-3 expression was not detectable in either invasive cancers or DCIS, with a consistent similarity in IGFBP-3 immunoreactivity in IDCs and DCIS. Positive IGFBP-3 expression showed a possible trend in association with increased proliferation (P = 0.096), oestrogen receptor (ER) negativity (P = 0.06) and HER-2 overexpression (P = 0.065) in invasive tumours and a strong association with ER negativity (P = 0.037) in DCIS. Although IGFBP-3 expression was not an independent prognosticator, IGFBP-3-positive breast cancers may have shorter disease-free and overall survivals, although these did not reach statistical significance. CONCLUSIONS: Increased breast epithelial IGFBP-3 expression is a feature of tumorigenesis with cytoplasmic immunoreactivity in the absence of significant nuclear localisation in IDCs and DCIS. There are trends between high levels of IGFBP-3 and poor prognostic features, suggesting that IGFBP-3 is a potential mitogen. IGFBP-3 is not an independent prognosticator for overall survival or disease-free survival, to reflect its dual effects on breast cancer growth regulated by complex pathways in vivo that may relate to its interactions with other growth factors
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