1,802 research outputs found

    Job Descriptions and Job Specifications for Directors of Special Education

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    It was the purpose of this study to analyze the available literature in the area of special education in an effort to compile a descriptive taxonomy of job descriptions and job specifications for directors of special education

    Implications of diphoton searches for a Radion in the Bulk-Higgs Scenario

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    In this work we point out that the apparent diphoton excess initially presented by the ATLAS and CMS collaborations could have originated from a radion in the bulk Higgs scenario within a warped extra dimension. In this scenario the couplings of the radion to massive gauge bosons are suppressed, allowing it to evade existing searches. In the presence of mixing with the Higgs, due to the strong constraints from diboson searches, only points near what we denominate the alignment region were able to explain the diphoton signal and evade other experimental constraints. In light of the new measurements presented at ICHEP 2016 by both LHC collaborations, which do not confirm the initial diphoton excess, we study the current and future collider constraints on a radion within the bulk-Higgs scenario. We find that searches in the diphoton channel provide the most powerful probe of this scenario and already exclude large regions of parameter space, particularly for smaller warp factors. The radion has a sizeable branching ratio into top pairs and this channel may also give competitive constraints in the future. Finally, diHiggs searches can provide a complementary probe in the case of non-zero radion-Higgs mixing but strong alignment.Comment: 20 pages, 12 figures. Several changes including consequences from ICHEP2016. Final version accepted by journa

    Radion/Dilaton-Higgs Mixing Phenomenology in Light of the LHC

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    Motivated by the bulk mixing ξR5H†H\xi R_5 H^{\dagger}H between a massive radion and a bulk scalar Higgs in warped extra dimensions, we construct an effective four dimensional action that---via the AdS/CFT correspondence---describes the most general mixing between the only light states in the theory, the dilaton and the Higgs. Due to conformal invariance, once the Higgs scalar is localized in the bulk of the extra-dimension the coupling between the dilaton and the Higgs kinetic term vanishes, implying a suppressed coupling between the dilaton and massive gauge bosons. We comment on the implications of the mixing and couplings to Standard Model particles. Identifying the recently discovered 125 GeV resonance with the lightest Higgs-like mixed state ϕ−\phi_{-}, we study the phenomenology and constraints for the heaviest radion-like state ϕ+\phi_{+}. In particular we find that in the small mixing scenario with a radion-like state ϕ+\phi_{+} in the mass range [150,250] GeV, the diphoton channel can provide the best chance of discovery at the LHC if the collaborations extend their searches into this energy range.Comment: 28 pages, 6 figures; v2: version published in JHE

    Novel Collider and Dark Matter Phenomenology of a Top-philic Z'

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    We consider extending the Standard Model by including an additional Abelian gauge group broken at low energies under which the right-handed top quark is the only effectively charged Standard Model fermion. The associated gauge boson (Z′)(Z') is then naturally top-philic and couples only to the rest of the SM particle content at loop-level or via kinetic mixing with the hypercharge gauge boson which is assumed to be small. Working at the effective theory level, we demonstrate that such a minimal extension allows for an improved fitting of the ∼2σ\sim 2\sigma excess observed in ttˉht\bar{t}h searches at the LHC in a region of parameter space that satisfies existing collider constraints. We also present the reach of the LHC at 13 TeV in constraining the relevant region of parameter space. Additionally we show that within the same framework a suitably chosen fermion charged only under the exotic Abelian group can, in the region of parameter space preferred by the tˉth\bar{t}th measurements, simultaneously explain the dark matter relic density and the γ\gamma-ray excess at the galactic center observed by the Fermi-LAT experiment.Comment: 30 pages, 11 figures; v2: version published in JHE

    The Spatial Correlation of Bent-Tail Galaxies and Galaxy Clusters

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    We have completed a deep radio continuum survey covering 86 square degrees of the Spitzer-South Pole Telescope deep field to test whether bent-tail galaxies are associated with galaxy clusters. We present a new catalogue of 22 bent-tail galaxies and a further 24 candidate bent-tail galaxies. Surprisingly, of the 8 bent-tail galaxies with photometric redshifts, only two are associated with known clusters. While the absence of bent-tail sources in known clusters may be explained by effects such as sensitivity, the absence of known clusters associated with most bent-tail galaxies casts doubt upon current models of bent-tail galaxies.Comment: Accepted by MNRA

    Predicted and observed evolution in the mean properties of Type Ia supernovae with redshift

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    Recent studies indicate that Type Ia supernovae (SNe Ia) consist of two groups - a "prompt" component whose rates are proportional to the host galaxy star formation rate, whose members have broader lightcurves and are intrinsically more luminous, and a "delayed" component whose members take several Gyr to explode, have narrower lightcurves, and are intrinsically fainter. As cosmic star formation density increases with redshift, the prompt component should begin to dominate. We use a two-component model to predict that the average lightcurve width should increase by 6% from z=0-1.5. Using data from various searches we find an 8.1% +/- 2.7% increase in average lightcurve width for non-subluminous SNe Ia from z=0.03 - 1.12, corresponding to an increase in the average intrinsic luminosity of 12%. To test whether there is any bias after supernovae are corrected for lightcurve shape we use published data to mimic the effect of population evolution and find no significant difference in the measured dark energy equation of state parameter, w. However, future measurements of time-variable w will require standardization of SN Ia magnitudes to 2% up to z=1.7, and it is not yet possible to assess whether lightcurve shape correction works at this level of precision. Another concern at z=1.5 is the expected order of magnitude increase in the number of SNe Ia that cannot be calibrated by current methods.Comment: 5 pages, 3 figures, accepted to ApJ Letters, addressed referee's comments, table adde

    The Development of Day-night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

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    The suprachiasmatic nucleus (SCN) exhibits circadian rhythmicity in fetal and infant rats, but little is known about the consequences of this rhythmicity for infant behavior. Here, in Experiment 1, we measured sleep and wakefulness in rats during the day and night in postnatal day (P)2, P8, P15 and P21 subjects. As early as P2, day-night differences in sleep-wake activity were detected. Nocturnal wakefulness began to emerge around P15 and was reliably expressed by P21. We hypothesized that the process of photic entrainment over the first postnatal week, which depends upon the development of connectivity between the retinohypothalamic tract (RHT) and the SCN, influences the later emergence of nocturnal wakefulness. To test this hypothesis, in Experiment 2 infant rats were enucleated bilaterally at P3 and P11, that is, before and after photic entrainment. Whereas pups enucleated at P11 and tested at P21 exhibited increased wakefulness at night, identical to sham controls, pups enucleated at P3 and tested at P21 exhibited the opposite pattern of increased wakefulness during the day. Pups tested at P28 and P35 exhibited this same pattern of increased daytime wakefulness. All together, these results suggest that prenatal and postnatal experience modulates the development of species-typical circadian sleep-wake patterns. Moreover, we suggest that visual system stimulation, via the RHT’s connections with the SCN, exerts an organizational influence on the developing circadian system and, consequently, contributes to the emergence of nocturnality in this species
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