233 research outputs found
Direct Detection Constraints on Dark Photon Dark Matter
Dark matter detectors built primarily to probe elastic scattering of WIMPs on
nuclei are also precise probes of light, weakly coupled particles that may be
absorbed by the detector material. In this paper, we derive constraints on the
minimal model of dark matter comprised of long-lived vector states V (dark
photons) in the 0.01-100 keV mass range. The absence of an ionization signal in
direct detection experiments such as XENON10 and XENON100 places a very strong
constraint on the dark photon mixing angle, down to , assuming
that dark photons comprise the dominant fraction of dark matter. This
sensitivity to dark photon dark matter exceeds the indirect bounds derived from
stellar energy loss considerations over a significant fraction of the available
mass range. We also revisit indirect constraints from decay and
show that limits from modifications to the cosmological ionization history are
comparable to the updated limits from the diffuse gamma-ray flux.Comment: 10 pages, 4 figures; numerical bug in J-factor corrected; main
results unchange
Directly Detecting MeV-scale Dark Matter via Solar Reflection
If dark matter (DM) particles are lighter than a few MeV/ and can
scatter off electrons, their interaction within the solar interior results in a
considerable hardening of the spectrum of galactic dark matter received on
Earth. For a large range of the mass vs. cross section parameter space, , the "reflected" component of the DM flux is far more energetic
than the endpoint of the ambient galactic DM energy distribution, making it
detectable with existing DM detectors sensitive to an energy deposition of
eV. After numerically simulating the small reflected component of the
DM flux, we calculate its subsequent signal due to scattering on detector
electrons, deriving new constraints on in the MeV and sub-MeV range
using existing data from the XENON10/100, LUX, PandaX-II, and XENON1T
experiments, as well as making projections for future low threshold direct
detection experiments.Comment: 6 pages, 4 figures; improved treatment of reflection process; limits
strengthened, conclusions otherwise unchange
Direct detection prospects of dark vectors with xenon-based dark matter experiments
Dark matter experiments primarily search for the scattering of WIMPs on
target nuclei of well shielded underground detectors. The results from liquid
scintillator experiments furthermore provide precise probes of very light and
very weakly coupled particles that may be absorbed by electrons. In these
proceedings we summarize previously obtained constraints on long-lived dark
matter vector particles (dark photons) in the keV mass range. In
addition, we provide a first projected sensitivity reach for the upcoming
XENON1T dark matter search to detect dark photons.Comment: 5 pages, 1 figure; proceedings of the European Physical Society
Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria;
reference adde
Solar Reflection of Dark Matter
The scattering of light dark matter off thermal electrons inside the Sun
produces a "fast" sub-component of the dark matter flux that may be detectable
in underground experiments. We update and extend previous work by analyzing the
signatures of dark matter candidates which scatter via light mediators. Using
numerical simulations of the dark matter-electron interaction in the solar
interior, we determine the energy spectrum of the reflected flux, and calculate
the expected rates for direct detection experiments. We find that large
Xenon-based experiments (such as XENON1T) provide the strongest direct limits
for dark matter masses below a few MeV, reaching a sensitivity to the effective
dark matter charge of .Comment: 24 pages, 13 figure
The intra- and extracellular proteome of Aspergillus niger growing on defined medium with xylose or maltose as carbon substrate
The filamentous fungus Aspergillus niger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillus niger, thus the homologous glucoamylase (glaA) promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is a potent inducer of glaA promoter controlled genes. For a more profound understanding of A. niger physiology, a comprehensive analysis of the intra- and extracellular proteome of Aspergillus niger AB1.13 growing on defined medium with xylose or maltose as carbon substrate was carried out using 2-D gel electrophoresis/Maldi-ToF and nano-HPLC MS/MS
Neutralization of Diverse Human Cytomegalovirus Strains Conferred by Antibodies Targeting Viral gH/gL/pUL128-131 Pentameric Complex
Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection, and developing a prophylactic vaccine is of high priority to public health. We recently reported a replication-defective human cytomegalovirus with restored pentameric complex glycoprotein H (gH)/gL/pUL128-131 for prevention of congenital HCMV infection. While the quantity of vaccine-induced antibody responses can be measured in a viral neutralization assay, assessing the quality of such responses, including the ability of vaccine-induced antibodies to cross-neutralize the field strains of HCMV, remains a challenge. In this study, with a panel of neutralizing antibodies from three healthy human donors with natural HCMV infection or a vaccinated animal, we mapped eight sites on the dominant virus-neutralizing antigen-the pentameric complex of glycoprotein H (gH), gL, and pUL128, pUL130, and pUL131. By evaluating the site-specific antibodies in vaccine immune sera, we demonstrated that vaccination elicited functional antiviral antibodies to multiple neutralizing sites in rhesus macaques, with quality attributes comparable to those of CMV hyperimmune globulin. Furthermore, these immune sera showed antiviral activities against a panel of genetically distinct HCMV clinical isolates. These results highlighted the importance of understanding the quality of vaccine-induced antibody responses, which includes not only the neutralizing potency in key cell types but also the ability to protect against the genetically diverse field strains. IMPORTANCE HCMV is the leading cause of congenital viral infection, and development of a preventive vaccine is a high public health priority. To understand the strain coverage of vaccine-induced immune responses in comparison with natural immunity, we used a panel of broadly neutralizing antibodies to identify the immunogenic sites of a dominant viral antigen-the pentameric complex. We further demonstrated that following vaccination of a replication-defective virus with the restored pentameric complex, rhesus macaques can develop broadly neutralizing antibodies targeting multiple immunogenic sites of the pentameric complex. Such analyses of site-specific antibody responses are imperative to our assessment of the quality of vaccine-induced immunity in clinical studies
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