2,702 research outputs found
Light Hidden Fermionic Dark Matter in Neutrino Experiments
We consider, in a model-independent framework, the potential for observing
dark matter in neutrino detectors through the interaction , where is a dark fermion. Operators of dimension six or less are
considered, and constraints are placed on their coefficients using the dark
matter lifetime and its decays to states which include rays or
pairs. After these constraints are applied, there remains one operator
which can possibly contribute to in neutrino detectors at
an observable level. We then consider the results from the Super-Kamiokande
relic supernova neutrino search and find that Super-K can probe the new physics
scale of this interaction up to O(100\mbox{ TeV}).Comment: 5, pages, 1 figure. To be published in the proceedings of DPF-2009,
Detroit, MI, July 2009, eConf C09072
Localized and Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events
We investigate an excess observed in hadronic events in the archived LEP2
ALEPH data. This excess was observed at preselection level during data-MC
comparisons of four-jet events when no search was being performed. The events
are clustered into four jets and paired such that the mass difference between
the two dijet systems is minimized. The excess occurs in the region
M_1+M_2\sim 110\mbox{ GeV}; about half of the excess is concentrated in the
region M_1\sim 80\mbox{ GeV}, M_2\sim 25\mbox{ GeV}, with a local
significance between and , depending on assumptions
about hadronization uncertainties. The other half of the events are in a broad
excess near M_1\sim M_2\sim 55\mbox{ GeV}; these display a local significance
of . We investigate the effects of changing the SM QCD Monte
Carlo sample, the jet-clustering algorithm, and the jet rescaling method. We
find that the excess is remarkably robust under these changes, and we find no
source of systematic uncertainty that can explain the excess. No analogue of
the excess is seen at LEP1.Comment: 40 pages, 17 figures. Version published in JHEP. Detector section
removed, S/B and SM expectation figure added, expanded discussion of
hadronization uncertainties, small changes in systematic errors due to LEP1
data statistics, table added with significance as a function of
center-of-mass energy, changes in tex
Lepton-Flavored Dark Matter
In this work, we address two paradoxes. The first is that the measured
dark-matter relic density can be satisfied with new physics at O(100 GeV - 1
TeV), while the null results from direct-detection experiments place lower
bounds of O(10 TeV) on a new-physics scale. The second puzzle is that the
severe suppression of lepton-flavor-violating processes involving electrons,
e.g. mu->3e, tau->e mu mu, etc., implies that generic new-physics contributions
to lepton interactions cannot exist below O(10 - 100 TeV), whereas the 3.6sigma
deviation of the muon g-2 from the standard model can be explained by a
new-physics scale < O(1 TeV). Here, we suggest that it may not be a coincidence
that both the muon g-2 and the relic density can be satisfied by a new-physics
scale < 1 TeV. We consider the possibility of a gauged lepton-flavor
interaction that couples at tree level only to mu- and tau-flavored leptons and
the dark sector. Dark matter thus interacts appreciably only with particles of
mu and tau flavor at tree level and has loop-suppressed couplings to quarks and
electrons. Remarkably, if such a gauged flavor interaction exists at a scale
O(100 GeV - 1 TeV), it allows for a consistent phenomenological framework,
compatible with the muon g-2, the relic density, direct detection, indirect
detection, charged-lepton decays, neutrino trident production, and results from
hadron and e+e- colliders. We suggest experimental tests for these ideas at
colliders and for low-energy observables.Comment: includes additional discussions, results unchange
Majorana Physics Through the Cabibbo Haze
We present a model in which the Supersymmetric Standard Model is augmented by
the family symmetry \bs{\m Z_7 \rtimes \m Z_3}. Motivated by , where
the charge two-thirds and neutral Dirac Yukawa matrices are related, we
propose, using family symmetry, a special form for the seesaw Majorana matrix;
it contains a squared correlated hierarchy, allowing it to mitigate the severe
hierarchy of the quark sector. It is reproduced naturally by the invariant
operators of \bs{\m Z_7 \rtimes \m Z_3}, with the hierarchy carried by
familon fields. In addition to relating the hierarchy of the to the sector, it contains a Gatto-Sartori-Tonin
like relation, predicts a normal hierarchy for Tri-bimaximal and Golden Ratio
mixings, and gives specific values for the light neutrino masses.Comment: 33 pages, 1 figure. This revised version omits a section where a
particular linear combination of dimension-five operators was mistakenly
claimed to produce the special form of the Majorana matrix. The main changes
are to the Introduction, Sec. 5.1 of the previous version, and Summary and
Conclusions. In addition to minor changes throughout, we have corrected an
erroneous sign in Eq. 1
Armillaria Root Rot in Eucalypt Forests: Aggravated Endemic Disease
Species of the woody root rot fungus Armillaria are indigenous
in cool temperate rain forest, mixed forest, and wet and dry sclerophyll
eucalypt forests in Australia. Four species have been described or identified
from southeastern Australia: A. luteobubalina Watling and Kile, A. fumosa
Kile and Watling, A. hinnulea Kile and Watling, and A. novae-zelandiae
(Stevenson) Boesewinkel. The latter species was first described from New
Zealand, and A. hinnulea also occurs in that country. Armillaria novae-zelandiae
and A. hinnulea occur in wet forests (rain forest, mixed forest, and wet sclerophyll
communities), while A. luteobubalina and A. fumosa are found mainly in
dry sclerophyll forests.
Armillaria luteobubalina is so far the only species known to behave as a
primary pathogen in native forests. While the fungus has an extensive geographical
distribution in southeastern Australia, damage is most severe in
selectively logged forests in the central highlands of Victoria, where it is
estimated that approximately 3-5% of the forest area is moderately to severely
affect~. The fungus kills all species of eucalypts and a wide range of the under-
story trees and shrubs present in the forests. Most infections occur in small
(0.1-1.0 ha), well-defined patches, but larger (up to 20-30 ha), more diffuse
infections also occur. Evidence of primary pathogenicity includes (a) constant
association of the fungus with disease; (b) the pattern of disease development
within stands (the fungus spreads by root contact from infected food bases);
(c) correlation between root infection and symptom development in large trees;
(d) evidence of host resistance to infection; and (e) pathogenicity in pot and
field trials. There is no evidence that climatic stress or other pests or pathogens
initiate disease.
Within the forest, the fungus has a discontinuous distribution. Studies of
genotypes of the fungus (identified by analyses of mating alleles, since Armillaria
sp. are bifactorial heterothallic, or intraspecific antagonism), suggest that A.
luteobubalina consists of a community of genetically distinct mycelia. Individual
genotypes may contract, expand, or coalesce, depending on circumstance. The
development and status of the community depends on the two processes of
new basidiospore infection and local spread by vegetative growth through root
systems. Similar patterns of genotype distribution and clonal development were
evident in logged and unlogged forest. It is concluded that root rot caused by
the fungus is endemic in these forests but that logging has aggravated the disease
Initiation of Procalcitonin Screening as a Marker in Antibiotic Therapy De-escalation
Problem: The overuse of antibiotics has created antimicrobial resistance (AMR)
resulting in treatment failure for bacterial infections. To combat AMR, clinicians should
only prescribe antibiotic therapy when clinically warranted. It is easy to misdiagnose a
viral infection. However, any delay in the initiation of antibiotic therapy in a bacterial
infection may lead to increased morbidity and mortality. These patients with non-specific
clinical symptoms may be misdiagnosed without a rapid and definitive diagnostic test.
Methods: This quality improvement (QI) initiative utilized an evidence-based clinical
guideline for procalcitonin (PCT) levels for antibiotic therapy de-escalation. WBC counts
were collected two-days and one-day before ID work-up along with PCT levels and white
blood cell (WBC) counts collected on day-1, day-3, and day-5 post infectious disease.
Data was collected via prospective chart review including the number of positive PCT
levels obtained versus positive cultures, average length of antibiotic use, number of
different antibiotics used, and the time until the bacterial infection was confirmed or
denied.
Results: The implemented PCT clinical guideline allowed for faster identification of
bacterial infections than standard blood cultures. There is significant evidence supporting
a positive relationship between elevated PCT levels and positive cultures. Over time the
level of PCT decreases showing a correlation with a reduction of the WBC count.
Implications for Practice: Use of the PCT clinical guideline can identify whether there
is a bacterial infection rapidly allowing for the initiation or de-escalation of antibiotic
therapy preventing further AMR resistance
It’s NOT Trash, It’s ART
Stepping off the plane in Hue, Vietnam took my breath away. I was slammed with heat and extreme humidity that is common for mid-May. I stood at the bottom of the jetway, trying to adjust not only to my new environment, but to the fact I took this leap of faith and traveled half way around the world to teach children with intellectual disabilities about art made from trash. Little did I know that that step would have such a huge impact on my life and further strengthen my core values
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