571 research outputs found

    Electroweak Constraints on Warped Geometry in Five Dimensions and Beyond

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    Here we consider the tree level corrections to electroweak (EW) observables from standard model (SM) particles propagating in generic warped extra dimensions. The scale of these corrections is found to be dominated by three parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK gauge fields to the Higgs and the relative coupling of the KK gauge fields to fermion zero modes. It is found that 5D spaces that resolve the hierarchy problem through warping typically have large gauge-Higgs coupling. It is also found in D>5D>5 where the additional dimensions are warped the relative gauge-Higgs coupling scales as a function of the warp factor. If the warp factor of the additional spaces is contracting towards the IR brane, both the relative gauge-Higgs coupling and resulting EW corrections will be large. Conversely EW constraints could be reduced by finding a space where the additional dimension's warp factor is increasing towards the IR brane. We demonstrate that the Klebanov Strassler solution belongs to the former of these possibilities.Comment: 18 pages, 3 figures (references added) version to appear in JHE

    Neutrino Mass and μe+γ\mu \rightarrow e + \gamma from a Mini-Seesaw

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    The recently proposed "mini-seesaw mechanism" combines naturally suppressed Dirac and Majorana masses to achieve light Standard Model neutrinos via a low-scale seesaw. A key feature of this approach is the presence of multiple light (order GeV) sterile-neutrinos that mix with the Standard Model. In this work we study the bounds on these light sterile-neutrinos from processes like \mu ---> e + \gamma, invisible Z-decays, and neutrinoless double beta-decay. We show that viable parameter space exists and that, interestingly, key observables can lie just below current experimental sensitivities. In particular, a motivated region of parameter space predicts a value of BR(\mu ---> e + \gamma) within the range to be probed by MEG.Comment: 1+26 pages, 7 figures. v2 JHEP version (typo's fixed, minor change to presentation, results unchanged

    KeV Warm Dark Matter and Composite Neutrinos

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    Elementary keV sterile Dirac neutrinos can be a natural ingredient of the composite neutrino scenario. For a certain class of composite neutrino theories, these sterile neutrinos naturally have the appropriate mixing angles to be resonantly produced warm dark matter (WDM). Alternatively, we show these sterile neutrinos can be WDM produced by an entropy-diluted thermal freeze-out, with the necessary entropy production arising not from an out-of-equilibrium decay, but rather from the confinement of the composite neutrino sector, provided there is sufficient supercooling.Comment: 12 pages, 2 figures, published versio

    Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model

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    In order to investigate the phenomenological implications of warped spaces in more than five dimensions, we consider a 4+1+δ4+1+\delta dimensional extension to the Randall and Sundrum model in which the space is warped with respect to a single direction by the presence of an anisotropic bulk cosmological constant. The Einstein equations are solved, giving rise to a range of possible spaces in which the δ\delta additional spaces are warped. Here we consider models in which the gauge fields are free to propagate into such spaces. After carrying out the Kaluza Klein (KK) decomposition of such fields it is found that the KK mass spectrum changes significantly depending on how the δ\delta additional dimensions are warped. We proceed to compute the lower bound on the KK mass scale from electroweak observables for models with a bulk SU(2)×U(1)SU(2)\times U(1) gauge symmetry and models with a bulk SU(2)R×SU(2)L×U(1)SU(2)_R\times SU(2)_L\times U(1) gauge symmetry. It is found that in both cases the most favourable bounds are approximately MKK2M_{KK}\gtrsim 2 TeV, corresponding to a mass of the first gauge boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4. New appendix added. Five additional figures. References adde

    Nonattendance in pediatric pulmonary clinics: an ambulatory survey

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    <p>Abstract</p> <p>Background</p> <p>Nonattendance for scheduled appointments disturbs the effective management of pediatric pulmonary clinics. We hypothesized that the reasons for non-attendance and the necessary solutions might be different in pediatric pulmonary medicine than in other pediatric fields. We therefore investigated the factors associated with nonattendance this field in order to devise a corrective strategy.</p> <p>Methods</p> <p>The effect of age, gender, ethnic origin, waiting time for an appointment and the timing of appointments during the day on nonattendance proportion were assessed. Chi-square tests were used to analyze statistically significant differences of categorical variables. Logistic regression models were used for multivariate analysis.</p> <p>Results</p> <p>A total of 1190 pediatric pulmonology clinic visits in a 21 month period were included in the study. The overall proportion of nonattendance was 30.6%. Nonattendance was 23.8% when there was a short waiting time for an appointment (1–7 days) and 36.3% when there was a long waiting time (8 days and above) (p-value < 0.001). Nonattendance was 28.7% between 8 a.m. to 3 p.m. and 37.5% after 3 p.m. (p = 0.007). Jewish rural patients had 15.4% nonattendance, Jewish urban patients had 31.2% nonattendance and Bedouin patients had 32.9% nonattendance (p < 0.004). Age and gender were not significantly associated with nonattendance proportions. A multivariate logistic regression model demonstrated that the waiting time for an appointment, time of the day, and the patients' origin was significantly associated with nonattendance.</p> <p>Conclusion</p> <p>The factors associated with nonattendance in pediatric pulmonary clinics include the length of waiting time for an appointment, the hour of the appointment within the day and the origin of the patient.</p

    Attention modulates adaptive motor learning in the ‘broken escalator’ paradigm

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    The physical stumble caused by stepping onto a stationary (broken) escalator represents a locomotor aftereffect (LAE) that attests to a process of adaptive motor learning. Whether such learning is primarily explicit (requiring attention resources) or implicit (independent of attention) is unknown. To address this question, we diverted attention in the adaptation (MOVING) and aftereffect (AFTER) phases of the LAE by loading these phases with a secondary cognitive task (sequential naming of a vegetable, fruit and a colour). Thirty-six healthy adults were randomly assigned to 3 equally sized groups. They performed 5 trials stepping onto a stationary sled (BEFORE), 5 with the sled moving (MOVING) and 5 with the sled stationary again (AFTER). A 'Dual-Task-MOVING (DTM)' group performed the dual-task in the MOVING phase and the 'Dual-Task-AFTEREFFECT (DTAE)' group in the AFTER phase. The 'control' group performed no dual task. We recorded trunk displacement, gait velocity and gastrocnemius muscle EMG of the left (leading) leg. The DTM, but not the DTAE group, had larger trunk displacement during the MOVING phase, and a smaller trunk displacement aftereffect compared with controls. Gait velocity was unaffected by the secondary cognitive task in either group. Thus, adaptive locomotor learning involves explicit learning, whereas the expression of the aftereffect is automatic (implicit). During rehabilitation, patients should be actively encouraged to maintain maximal attention when learning new or challenging locomotor tasks

    Heterogeneous consumption in OLG model with horizontal innovations

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    The paper develops a general equilibrium endogenous growth model involving heterogeneous consumption by an age-structured population with uncertain but limited life span and balanced life-time budget without bequests. The heterogeneity is introduced via weights which the individuals attribute in their utility function to consumption of different goods depending on the vintage of the good. The goods are produced by monopolistically competitive firms and the variety of available goods/technologies is determined endogenously through R&D investments. A competitive bank sector provides financial resources for investments, secured by agents’ savings and future firms profits. The general equilibrium is characterized by a system of functional equations and is analytically or numerically determined for several particular weight functions. It is shown that the investments by agents alone may be insufficient to sustain growth, while additional investments provided by the bank sector may lead to growth. The resulting imbalance between agents’ assets and the total value of firms can grow unboundedly in the case of homogeneous consumption. The results exhibit the qualitative difference between the dynamics of the model with heterogeneous versus homogeneous consumption. In particular heterogeneous con- sumption (when old goods are discounted) reduces the additional investments by the financial sector so that the values of firms become balanced by the assets of agents in the long run.info:eu-repo/semantics/publishedVersio

    Surgical and medical second trimester abortion in South Africa: A cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>A high percentage of abortions performed in South Africa are in the second trimester. However, little research focuses on women's experiences seeking second trimester abortion or the efficacy and safety of these services.</p> <p>The objectives are to document clinical and acceptability outcomes of second trimester medical and surgical abortion as performed at public hospitals in the Western Cape Province.</p> <p>Methods</p> <p>We performed a cross-sectional study of women undergoing abortion at 12.1-20.9 weeks at five hospitals in Western Cape Province, South Africa in 2008. Two hundred and twenty women underwent D&E with misoprostol cervical priming, and 84 underwent induction with misoprostol alone. Information was obtained about the procedure and immediate complications, and women were interviewed after recovery.</p> <p>Results</p> <p>Median gestational age at abortion was earlier for D&E clients compared to induction (16.0 weeks vs. 18.1 weeks, p < 0.001). D&E clients reported shorter intervals between first clinic visit and abortion (median 17 vs. 30 days, p < 0.001). D&E was more effective than induction (99.5% vs. 50.0% of cases completed on-site without unplanned surgical procedure, p < 0.001). Although immediate complications were similar (43.8% D&E vs. 52.4% induction), all three major complications occurred with induction. Early fetal expulsion occurred in 43.3% of D&E cases. While D&E clients reported higher pain levels and emotional discomfort, most women were satisfied with their experience.</p> <p>Conclusions</p> <p>As currently performed in South Africa, second trimester abortions by D&E were more effective than induction procedures, required shorter hospital stay, had fewer major immediate complications and were associated with shorter delays accessing care. Both services can be improved by implementing evidence-based protocols.</p

    Warped Radion Dark Matter

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    Warped scenarios offer an appealing solution to the hierarchy problem. We consider a non-trivial deformation of the basic Randall-Sundrum framework that has a KK-parity symmetry. This leads to a stable particle beyond the Standard Model, that is generically expected to be the first KK-parity odd excitation of the radion field. We consider the viability of the KK-radion as a DM candidate in the context of thermal and non-thermal production in the early universe. In the thermal case, the KK-radion can account for the observed DM density when the radion decay constant is in the natural multi-TeV range. We also explore the effects of coannihilations with the first KK excitation of the RH top, as well as the effects of radion-Higgs mixing, which imply mixing between the KK-radion and a KK-Higgs (both being KK-parity odd). The non-thermal scenario, with a high radion decay constant, can also lead to a viable scenario provided the reheat temperature and the radion decay constant take appropriate values, although the reheat temperature should not be much higher than the TeV scale. Direct detection is found to be feasible if the DM has a small (KK-parity odd) Higgs admixture. Indirect detection via a photon signal from the galactic center is an interesting possibility, while the positron and neutrino fluxes from KK-radion annihilations are expected to be rather small. Colliders can probe characteristic aspects of the DM sector of warped scenarios with KK-parity, such as the degeneracy between the radion and the KK-radion (DM) modes.Comment: 43 pages, 16 figures; added reference
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