223 research outputs found
The Genomic Tools for Sweetpotato Improvement (GT4SP) Project
This flyer introduces a new four year investment to develop genomic and genetic resources for sweetpotato improvement that has been launched with the goal of establishing a molecular marker-assisted breeding program in sweetpotato. It provides information about the critical scientific constraints to be addressed, the strategies and the partners participating in the project
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
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
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
Longitudinal WW scattering in light of the 'Higgs boson' discovery
WW scattering is dominated at high energies by their longitudinal components, which are the most sensitive to the nature of the electroweak symmetry breaking. Prior to the discovery at the LHC of a Higgs-like particle, unitarization tools were extensively used to show that, in the absence of a light Higgs boson, new resonances resulting from the would-be strongly interacting electroweak sector would appear, and furthermore these techniques would approximately predict their masses, widths, and signal strengths. With the discovery of a Higgs-like particle now firmly established, we reinvestigate these techniques assuming this particle couples exactly as in the standard model (SM), but still being open to the possibility of an extended symmetry breaking sector. While the SM itself is free from problems with perturbative unitarity in the electroweak sector, "anomalous" self-couplings of the vector bosons low-energy remnants of such higher-energy symmetry breaking sectors are easily shown to reintroduce them. We demonstrate how new resonances should still appear in the scattering of electroweak vector bosons after imposing constraints from unitarity, and we discuss their ability to be probed with current and future LHC data
Radiative corrections to WL WL scattering in composite Higgs models
The scattering of longitudinally polarized electroweak bosons is likely to play an important role in the elucidation of the fundamental nature of the electroweak symmetry breaking sector and in determining the Higgs interactions with this sector. In this paper, by making use of the equivalence theorem, we determine the renormalization properties of the electroweak effective theory parameters in a model with generic Higgs couplings to the W and Z bosons. When the couplings between the Higgs and the electroweak gauge bosons deviate from their Standard Model values, additional counterterms of O(p4) in the usual chiral counting are required. We also determine in the same approximation the full radiative corrections to the WLWL→ZLZL process in this type of model. Assuming custodial invariance, all the related processes can be easily derived from this amplitude
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