775 research outputs found
Implications of diphoton searches for a Radion in the Bulk-Higgs Scenario
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
Motivated by the bulk mixing 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 , we study the
phenomenology and constraints for the heaviest radion-like state . In
particular we find that in the small mixing scenario with a radion-like state
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'
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
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
excess observed in 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 measurements, simultaneously
explain the dark matter relic density and the -ray excess at the
galactic center observed by the Fermi-LAT experiment.Comment: 30 pages, 11 figures; v2: version published in JHE
Adenovirus infection in the lung results in graft failure after lung transplantation
AbstractObjectives: Our goal was to examine the relationship between viral pneumonia and outcome in pediatric patients undergoing lung or heart-lung transplantation. Methods: Prospective surveillance for common respiratory viruses of childhood was performed in all patients undergoing lung or heart-lung transplantation. Specimens were examined for the presence of replicating virus (by culture), viral genome (by polymerase chain reaction), and viral antigen (by immunofluorescence and immunohistochemical staining). The relationship between viral infection and outcome was examined. Results: Sixteen patients underwent 19 transplants during the study period, with follow-up of 1 to 26 months. Virus was identified in the transplanted lung in 29 instances; adenovirus was identified most commonly (8/16 patients) and had the greatest impact on outcome. In 2 patients with early, fulminant infection, adenovirus was also identified in the donor. Adenovirus was significantly associated with respiratory failure leading to death or graft loss and with the histologic diagnosis of obliterative bronchiolitis (P ≤ .002 in each case). Conclusions: Adenovirus infection in the transplanted lung is significantly associated with graft failure, histologic obliterative bronchiolitis, and death. Health care personnel and families must be vigilant in preventing exposure of transplant recipients to this virus. Availability of a rapid and reliable test for adenovirus in donors and recipients would have an impact on management and could improve outcome for pediatric lung recipients. (J Thorac Cardiovasc Surg 1998;116:617-23
Assessment of changes in ecosystem service delivery:a historical perspective on catchment landscapes
Although the relationships between habitats and ecosystem services (ESs) have been acknowledged, investigating spatio-temporal change in these has received far less attention. This study assesses the influence of habitat changes on ES delivery across space and time, based on two time points some 60Â years apart, 1946 and 2009. A 1946 aerial photo coverage of two catchments in Scotland was used to construct digital photo mosaics which were then visually interpreted and digitised to derive historic habitat maps. Using the Spatial Evidence for Natural Capital Evaluation (SENCE) mapping approach, the derived habitat maps were translated into ES maps. These were then compared with contemporary ES maps of the two catchments, using the same mapping methodology. Increases in provisioning ESs were associated with increases in intensively managed habitats, with reductions in supply capacity of other regulating and supporting ESs associated with loss of semi-natural habitats. ES delivery was affected not only by gross area changes in habitats over time, but also by changes in configuration and spatial distribution of constituent habitats, including fragmentation and connectivity. It is argued that understanding historic changes in ESs adds an important strand in providing baselines to inform options for current and future management of catchments
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