504 research outputs found

    Hidden Extra U(1) at the Electroweak/TeV Scale

    Full text link
    We propose a simple extension of the Standard Model (SM) by adding an extra U(1) symmetry which is hidden from the SM sector. Such a hidden U(1) has not been considered before, and its existence at the TeV scale can be explored at the LHC. This hidden U(1) does not couple directly to the SM particles, and couples only to new SU(2)_L singlet exotic quarks and singlet Higgs bosons, and is broken at the TeV scale. The dominant signals at the high energy hadron colliders are multi lepton and multi b-jet final states with or without missing energy. We calculate the signal rates as well as the corresponding Standard Model background for these final states. A very distinctive signal is 6 high p_T b-jets in the final state with no missing energy. For a wide range of the exotic quarks masses the signals are observable above the background at the LHC.Comment: 19 pages, 5 figure

    Proximity effect in Nb-Mo layered films: Transition temperature and critical current dependence on period

    Full text link
    The behavior of the transition temperature and critical current density for a Mo/Nb repeated bilayer system as a function of the number of periods was explored. The measured values of the transition temperature are compared to the theoretical predictions for the proximity effect in the dirty limit. We find that the transition temperature does not decrease as the number of periods increase. In addition, inductive critical current density measurements also show a scaling that indicates the superconductivity properties are not dependent on the number of bilayers.Comment: 13 pages, 6 figures, to be published Journal of Applied Physic

    Initial determination of the spins of the gluino and squarks at LHC

    Full text link
    In principle particle spins can be measured from their production cross sections once their mass is approximately known. The method works in practice because spins are quantized and cross sections depend strongly on spins. It can be used to determine, for example, the spin of the top quark. Direct application of this method to supersymmetric theories will have to overcome the challenge of measuring mass at the LHC, which could require high statistics. In this article, we propose a method of measuring the spins of the colored superpatners by combining rate information for several channels and a set of kinematical variables, without directly measuring their masses. We argue that such a method could lead to an early determination of the spin of gluino and squarks. This method can be applied to the measurement of spin of other new physics particles and more general scenarios.Comment: 23 pages, 8 figures, minor change

    Searching for the light dark gauge boson in GeV-scale experiments

    Full text link
    We study current constraints and search prospects for a GeV scale vector boson at a range of low energy experiments. It couples to the Standard Model charged particles with a strength <= 10^-3 to 10^-4 of that of the photon. The possibility of such a particle mediating dark matter self-interactions has received much attention recently. We consider searches at low energy high luminosity colliders, meson decays, and fixed target experiments. Based on available data, searches both at colliders and in meson decays can discover or exclude such a scenario if the coupling strength is on the larger side. We emphasize that a dedicated fixed target experiment has a much better potential in searching for such a gauge boson, and outline the desired properties of such an experiment. Two different optimal designs should be implemented to cover the range of coupling strength 10^-3 to 10^-5, and < 10^-5 of the photon, respectively. We also briefly comment on other possible ways of searching for such a gauge boson.Comment: 33 pages, 5 figures; v2: corrected discussion of Upsilon decays, updates to discussion of fixed-target experiments and QED constraints, numerous minor changes, references added; v3: typo corrected relative to the JHEP published versio

    Pregnancy complications as markers for subsequent maternal cardiovascular disease: Validation of a maternal recall questionnaire

    Get PDF
    Background: We designed and tested the validity of a questionnaire to characterize maternal recall of pregnancy complications associated with increased future cardiovascular disease risk, based on the 2011 American Heart Association (AHA) guidelines. Methods: A maternal recall questionnaire of pregnancy history was administered to 971 patients who had participated in a previous cohort study of 1,608 pregnant women. Medical records from the study pregnancy served as the gold standard. Prevalence, sensitivity (sens), specificity (spec), positive predictive value (PPV), negative predictive value (NPV), and/or Spearman's correlation coefficients (r) were calculated for each question. Results: A total of 526 (54%) individuals recontacted responded. Respondents were more likely to be older, white, educated, and nulliparous and were less likely to deliver low-birthweight infants in the study pregnancy than were individuals who did not respond. Mean length of recall was 4.35 years (standard deviation [SD] 0.46) postpartum. Maternal recall was most accurate for gestational diabetes (sens: 92%, spec: 98%, PPV: 79%, NPV: 99%), infant birthweight (r=0.95), and gestation length (r=0.85). Maternal recall was modest for preeclampsia (sens: 79%, spec: 97%, PPV: 68%, NPV: 98%) and pregnancy-associated hypertension, including preeclampsia or gestational hypertension (sens: 60%, spec: 95%, PPV: 64%, NPV: 94%). Conclusions: This validation study demonstrated that the majority of women could accurately recall a history of gestational diabetes, infant birthweight, and gestational age at delivery, 4 years postpartum on average. Recall of preeclampsia and pregnancy-associated hypertension overall was modest. Maternal report of these pregnancy conditions may help clinicians identify women at increased risk for cardiovascular disease

    A novel HIV vaccine adjuvanted by IC31 induces robust and persistent humoral and cellular immunity.

    Get PDF
    The HIV vaccine strategy that, to date, generated immune protection consisted of a prime-boost regimen using a canarypox vector and an HIV envelope protein with alum, as shown in the RV144 trial. Since the efficacy was weak, and previous HIV vaccine trials designed to generate antibody responses failed, we hypothesized that generation of T cell responses would result in improved protection. Thus, we tested the immunogenicity of a similar envelope-based vaccine using a mouse model, with two modifications: a clade C CN54gp140 HIV envelope protein was adjuvanted by the TLR9 agonist IC31®, and the viral vector was the vaccinia strain NYVAC-CN54 expressing HIV envelope gp120. The use of IC31® facilitated immunoglobulin isotype switching, leading to the production of Env-specific IgG2a, as compared to protein with alum alone. Boosting with NYVAC-CN54 resulted in the generation of more robust Th1 T cell responses. Moreover, gp140 prime with IC31® and alum followed by NYVAC-CN54 boost resulted in the formation and persistence of central and effector memory populations in the spleen and an effector memory population in the gut. Our data suggest that this regimen is promising and could improve the protection rate by eliciting strong and long-lasting humoral and cellular immune responses

    First-Trimester Urine Concentrations of Phthalate Metabolites and Phenols and Placenta miRNA Expression in a Cohort of U.S. Women

    Get PDF
    Background: There is increasing concern that early-life exposure to endocrine-disrupting chemicals (EDCs) can influence the risk of disease development. Phthalates and phenols are two classes of suspected EDCs that are used in a variety of everyday consumer products, including plastics, epoxy resins, and cosmetics. In utero exposure to EDCs may affect disease propensity through epigenetic mechanisms. Objective: The objective of this study was to determine whether prenatal exposure to multiple EDCs is associated with changes in miRNA expression of human placenta, and whether miRNA alterations are associated with birth outcomes. Methods: Our study was restricted to a total of 179 women co-enrolled in the Harvard Epigenetic Birth Cohort and the Predictors of Preeclampsia Study. We analyzed associations between first-trimester urine concentrations of 8 phenols and 11 phthalate metabolites and expression of 29 candidate miRNAs in placenta by qRT-PCR. Results: For three miRNAs—miR-142-3p, miR15a-5p, and miR-185—we detected associations between Σphthalates or Σphenols on expression levels (p < 0.05). By assessing gene ontology enrichment, we determined the potential mRNA targets of these microRNAs predicted in silico were associated with several biological pathways, including the regulation of protein serine/threonine kinase activity. Four gene ontology biological processes were enriched among genes significantly correlated with the expression of miRNAs associated with EDC burden. Conclusions: Overall, these results suggest that prenatal phenol and phthalate exposure is associated with altered miRNA expression in placenta, suggesting a potential mechanism of EDC toxicity in humans. Citation LaRocca J, Binder AM, McElrath TF, Michels KB. 2016. First-trimester urine concentrations of phthalate metabolites and phenols and placenta miRNA expression in a cohort of U.S. women. Environ Health Perspect 124:380–387; http://dx.doi.org/10.1289/ehp.140840

    Radion effects on unitarity in gauge-boson scattering

    Get PDF
    The scalar field associated with fluctuations in the positions of the two branes, the ``radion'', plays an important role determining the cosmology and collider phenomenology of the Randall-Sundrum solution to the hierarchy problem. It is now well known that the radion mass is of order the weak scale, and that its couplings to standard model fields are order 1/TeV to the trace of the energy momentum tensor. We calculate longitudinal vector boson scattering amplitudes to explore the constraints on the radion mass and its coupling from perturbative unitarity. The scattering cross section can indeed become non-perturbative at energies prior to reaching the TeV brane cutoff scale, but only when some curvature-Higgs mixing on the TeV brane is present. We show that the coefficient of the curvature-Higgs mixing operator must be less than about 3 for the 4-d effective theory to respect perturbative unitarity up to the TeV brane cutoff scale. Mass bounds on the Higgs boson and the radion are also discussed.Comment: 17 pages, LaTeX, 5 eps figures, uses epsf.sty and axodraw.st

    Effects of genuine dimension-six Higgs operators

    Get PDF
    We systematically discuss the consequences of genuine dimension-six Higgs operators. These operators are not subject to stringent constraints from electroweak precision data. However, they can modify the couplings of the Higgs boson to electroweak gauge bosons and, in particular, the Higgs self-interactions. We study the sensitivity to which those couplings can be probed at future \ee linear colliders in the sub-TeV and in the multi-TeV range. We find that for s=500\sqrt s=500 GeV with a luminosity of 1 ab1^{-1} the anomalous WWHWWH and ZZHZZH couplings may be probed to about the 0.01 level, and the anomalous HHHHHH coupling to about the 0.1 level.Comment: 21 pages, 17 figures; typos corrected and references adde
    corecore