3,901 research outputs found
Flavor and CP violating physics from new supersymmetric thresholds
Treating the MSSM as an effective theory, we study the implications of having
dimension five operators in the superpotential for flavor and CP-violating
processes, exploiting the linear decoupling of observable effects with respect
to the new threshold scale \Lambda. We show that the assumption of weak scale
supersymmetry, when combined with the stringent limits on electric dipole
moments and lepton flavor-violating processes, provides sensitivity to \Lambda
as high as 10^7-10^9 GeV, while the next generation of experiments could
directly probe the high-energy scales suggested by neutrino physics.Comment: 4 pages, 1 figur
Notes on the Norman vocabulary
The Norman Manuscript, containing- a vocabulary
and notes on customs in use among Tasmanian
Aboriginals, was recently discovered among the archives
deposited in the Tasmanian Museum, Hobart, and is now
published in full in the Transactions of the Royal Society
of Tasmania.
It is of great value, as containing what is probably
the only vocabulary now extant in the original manuscript,
and also a number of incidental notes written by
the same hand
Crustal and upper mantle electrical conductivity structures in West Africa : geodynamic implications
Multi-lepton Signatures of a Hidden Sector in Rare B Decays
We explore the sensitivity of flavour changing b -> s transitions to a
(sub-)GeV hidden sector with generic couplings to the Standard Model through
the Higgs, vector and axion portals. The underlying two-body decays of B
mesons, B -> X_s S and B0 -> SS, where S denotes a generic new GeV-scale
particle, may significantly enhance the yield of monochromatic lepton pairs in
the final state via prompt decays of S to a dilepton pair. Existing
measurements of the charged lepton spectrum in neutral-current semileptonic B
decays provide bounds on the parameters of the light sector that are
significantly more stringent than the requirements of naturalness. New search
modes, such as B -> X_s + n(l+l-) and B0 -> n(l+l-) with n > 1 can provide
additional sensitivity to scenarios in which both the Higgs and vector portals
are active, and are accessible to (super-)B factories and hadron colliders.Comment: 12 pages, 2 figures; v2: reference added, minor correction
Resonant scattering and recombination of pseudo-degenerate WIMPs
We consider the direct and indirect detection signatures of WIMPs \chi^0 in
kinematic regimes with a heavier, but nearly degenerate, charged state
\chi^{+-}. For small splittings of O(10) MeV, the scattering of WIMPs off
nuclei may be dominated by inelastic recombination processes mediated by the
formation of (\chi^- N) bound states, leading to a distinct signature for
direct detection. These cross-sections are bound primarily by limits on the
abundance of heavy isotopes, and may be considerably larger than the elastic
scattering cross section in more conventional models. If the mass splitting is
too large for recombination to occur, there may still be a significant resonant
enhancement of loop-induced electromagnetic form-factors of the WIMP, which can
enhance the elastic scattering cross-section. We also discuss how this regime
affects the annihilation cross-section and indirect detection signatures, and
note the possibility of a significant mono-energetic \gamma-signal, mediated by
resonant processes near the (\chi^+\chi^-) bound state threshold.Comment: 22 pages, 6 figures; v2: typos corrected, to appear in Phys. Rev.
Discovery of spatial periodicities in a coronal loop using automated edge-tracking algorithms
A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations
Common Genetic Variant Association with Altered HLA Expression, Synergy with Pyrethroid Exposure, and Risk for Parkinson's Disease: An Observational and Case-Control Study.
Background/objectivesThe common non-coding single nucleotide polymorphism (SNP) rs3129882 in HLA-DRA is associated with risk for idiopathic Parkinson's disease (PD). The location of the SNP in the major histocompatibility complex class II (MHC-II) locus implicates regulation of antigen presentation as a potential mechanism by which immune responses link genetic susceptibility to environmental factors in conferring lifetime risk for PD.MethodsFor immunophenotyping, blood cells from 81 subjects were analyzed by qRT-PCR and flow cytometry. A case-control study was performed on a separate cohort of 962 subjects to determine association of pesticide exposure and the SNP with risk of PD.ResultsHomozygosity for G at this SNP was associated with heightened baseline expression and inducibility of MHC class II molecules in B cells and monocytes from peripheral blood of healthy controls and PD patients. In addition, exposure to a commonly used class of insecticide, pyrethroids, synergized with the risk conferred by this SNP (OR = 2.48, p = 0.007), thereby identifying a novel gene-environment interaction that promotes risk for PD via alterations in immune responses.ConclusionsIn sum, these novel findings suggest that the MHC-II locus may increase susceptibility to PD through presentation of pathogenic, immunodominant antigens and/or a shift toward a more pro-inflammatory CD4+ T cell response in response to specific environmental exposures, such as pyrethroid exposure through genetic or epigenetic mechanisms that modulate MHC-II gene expression
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