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 $W$ 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 $\sim$7% in discovery reach of hadronic $W$ 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