2,615 research outputs found
Tagging Boosted Ws with Wavelets
We present a new technique for distinguishing the hadronic decays of boosted
heavy particles from QCD backgrounds based on wavelet transforms. As an initial
exploration, we illustrate the technique in the particular case of hadronic
boson decays, comparing it to the ``mass drop'' cut currently used by the LHC
experiments. We apply wavelet cuts, which make use of complementary
information, and in combination with the mass drop cut results in an
improvement of 7% in discovery reach of hadronic boson final states
over a wide range of transverse momenta.Comment: 14 pages, 5 figure
Constraints on Light Majorana Dark Matter from Colliders
We explore model-independent collider constraints on light Majorana dark
matter particles. We find that colliders provide a complementary probe of WIMPs
to direct detection, and give the strongest current constraints on light DM
particles. Collider experiments can access interactions not probed by direct
detection searches, and outperform direct detection experiments by about an
order of magnitude for certain operators in a large part of parameter space.
For operators which are suppresssed at low momentum transfer, collider searches
have already placed constraints on such operators limiting their use as an
explanation for DAMA.Comment: 4 pages, 6 figure
Five-Year Study of Geocarpon minimum at Warren Prairie Natural Area Bradley County, Arkansas
Geocarpon minimum, listed by the U.S. Fish & Wildlife Service as threatened, was monitored at Warren Prairie Natural Area, Bradley County, Arkansas, 1986-90. Selected environmental variables were compared with Geocarpon productivity plot by plot. Principal components (PC) analysis generated two eigenvectors that jointly accounted for 30% of the variation among plots. PC-l describes an exposure gradient; high-productivity plots had less litter and grass cover, more cryptogamic lip, and more iron nodules lying on the surface than most other plots. PC-II was more useful for separating highly productive plots from all other plots; the highly productive plots lay in close proximity to slicks and remote from low spots where shallow water stands after a rain. Geocarpon productivity at Warren Prairie Natural Area peaked in 1987 and has declined steeply and steadily in the following years. Recommendations for further study are offere
Constraints on Dark Matter from Colliders
We show that colliders can impose strong constraints on models of dark
matter, in particular when the dark matter is light. We analyze models where
the dark matter is a fermion or scalar interacting with quarks and/or gluons
through an effective theory containing higher dimensional operators which
represent heavier states that have been integrated out of the effective field
theory. We determine bounds from existing Tevatron searches for monojets as
well as expected LHC reaches for a discovery. We find that colliders can
provide information which is complementary or in some cases even superior to
experiments searching for direct detection of dark matter through its
scattering with nuclei. In particular, both the Tevatron and the LHC can
outperform spin dependent searches by an order of magnitude or better over much
of parameter space, and if the dark matter couples mainly to gluons, the LHC
can place bounds superior to any spin independent search.Comment: 23 pages, 16 figure
LHC Bounds on Interactions of Dark Matter
We derive limits on the interactions of dark matter with quarks from ATLAS
null searches for jets + missing energy based on ~1 fb^-1 of integrated
luminosity, using a model-insensitive effective theory framework. We find that
the new limits from the LHC significantly extend limits previously derived from
CDF data at the Tevatron. Translated into the parameter space of direct
searches, these limits are particularly effective for ~GeV mass WIMPs. Our
limits indicate tension with isospin violating models satisfying minimal flavor
violation which attempt to reconcile the purported CoGeNT excess with
Xenon-100, indicating that either a light mediator or nontrivial flavor
structure for the dark sector is necessary for a viable reconciliation of
CoGeNT with Xenon.Comment: 20 pages, 11 figure
- …