16 research outputs found
Recoil detection of the lightest neutralino in MSSM singlet extensions
We investigate the correlated predictions of singlet extended MSSM models for direct detection and the cosmological relic density of the lightest neutralino. To illustrate the general effects of the singlet, we take heavy sleptons and squarks. We apply CERN LEP, (g−2)μ, and perturbativity constraints. We find that the WMAP upper bound on the cold dark matter density limits much of the parameter space to regions where the lightest neutralino can be discovered in recoil experiments. The results for the next-to-minimal supersymmetric standard model and U(1)′-extended minimal supersymmetric standard model are typically similar to the MSSM since their light neutralinos have similar compositions and masses. In the nearly minimal supersymmetric standard model the neutralino is often very light and its recoil detection is within the reach of the CDMS II experiment. In general, most points in the parameter spaces of the singlet models we consider are accessible to the WARP experiment
The Effect of Substructure on Mass Estimates of Galaxies
Large galaxies are thought to form hierarchically, from the accretion and
disruption of many smaller galaxies. Such a scenario should naturally lead to
galactic phase-space distributions containing some degree of substructure. We
examine the errors in mass estimates of galaxies and their dark halos made
using the projected phase-space distribution of a tracer population (such as a
globular cluster system or planetary nebulae) due to falsely assuming that the
tracers are distributed randomly. The level of this uncertainty is assessed by
applying a standard mass estimator to samples drawn from 11 random realizations
of galaxy halos containing levels of substructure consistent with current
models of structure formation. We find that substructure will distort our mass
estimates by up to ~20% - a negligible error compared to statistical and
measurement errors in current derivations of masses for our own and other
galaxies. However, this represents a fundamental limit to the accuracy of any
future mass estimates made under the assumption that the tracer population is
distributed randomly, regardless of the size of the sample or the accuracy of
the measurements.Comment: 9 pages, 8 figures, Astrophysical Journal, in pres
Triple-Top Signal of New Physics at the LHC
We present leading-order (LO) cross sections for the production of three top
quarks (tt\tb,t\tb\tb) at the Large Hadron Collider (LHC). We find a total
LO cross section for triple-top production in the Standard Model of fb at TeV and we give examples of two new physics
models which have a significant enhancement to this channel. In the Minimal
Supersymmetric Standard Model (MSSM), there are regions of parameter space
where the decays of gluino pairs into final states including three tops has a
cross section fb. In a leptophobic model featuring
right-handed couplings of the -quark to the top, we find
fb. With efficient identification and reconstruction of the top quarks, the
triple-top signal could potentially provide evidence for new physics at the
LHC.Comment: 12 pages, 5 figures, 3 table
Potato Breeding and Variety Development for Improved Quality and Pest Resistance in the Eastern United States
The eastern U.S. potato industry needs new potato varieties to overcome pest problems while reducing agricultural chemical use and to enhance marketing opportunities. This project will conduct potato breeding, germplasm enhancement, and selection studies to improve potato productivity and quality for important eastern U.S. markets. Novel and highly improved potato germplasm and varieties will be developed to reduce the impact of economically important potato pests, such as golden nematode, late blight, pink rot, and scab