3,015 research outputs found
Measuring a Light Neutralino Mass at the ILC: Testing the MSSM Neutralino Cold Dark Matter Model
The LEP experiments give a lower bound on the neutralino mass of about 46 GeV
which, however, relies on a supersymmetric grand unification relation. Dropping
this assumption, the experimental lower bound on the neutralino mass vanishes
completely. Recent analyses suggest, however, that in the minimal
supersymmetric standard model (MSSM), a light neutralino dark matter candidate
has a lower bound on its mass of about 7 GeV. In light of this, we investigate
the mass sensitivity at the ILC for very light neutralinos. We study slepton
pair production, followed by the decay of the sleptons to a lepton and the
lightest neutralino. We find that the mass measurement accuracy for a few-GeV
neutralino is around 2 GeV, or even less if the relevant slepton is
sufficiently light. We thus conclude that the ILC can help verify or falsify
the MSSM neutralino cold dark matter model even for very light neutralinos.Comment: 7 pages, 1 figure; references adde
The random case of Conley's theorem
The well-known Conley's theorem states that the complement of chain recurrent
set equals the union of all connecting orbits of the flow on the compact
metric space , i.e. , where
denotes the chain recurrent set of , stands for
an attractor and is the basin determined by . In this paper we show
that by appropriately selecting the definition of random attractor, in fact we
define a random local attractor to be the -limit set of some random
pre-attractor surrounding it, and by considering appropriate measurability, in
fact we also consider the universal -algebra -measurability besides -measurability, we are able to obtain
the random case of Conley's theorem.Comment: 15 page
Recommended from our members
Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases
Airborne estimates of greenhouse gas emissions are becoming more
prevalent with the advent of rapid commercial development of trace gas
instrumentation featuring increased measurement accuracy, precision, and
frequency, and the swelling interest in the verification of current emission
inventories. Multiple airborne studies have indicated that emission
inventories may underestimate some hydrocarbon emission sources in USÂ oil-
and gas-producing basins. Consequently, a proper assessment of the accuracy
of these airborne methods is crucial to interpreting the meaning of such
discrepancies. We present a new method of sampling surface sources of any
trace gas for which fast and precise measurements can be made and apply it to
methane, ethane, and carbon dioxide on spatial scales of  ∼ 1000 m,
where consecutive loops are flown around a targeted source region at
multiple altitudes. Using Reynolds decomposition for the scalar
concentrations, along with Gauss's theorem, we show that the method
accurately accounts for the smaller-scale turbulent dispersion of the local
plume, which is often ignored in other average mass balance methods. With
the help of large eddy simulations (LES) we further show how the circling
radius can be optimized for the micrometeorological conditions encountered
during any flight. Furthermore, by sampling controlled releases of methane
and ethane on the ground we can ascertain that the accuracy of the method, in
appropriate meteorological conditions, is often better than 10 %, with
limits of detection below 5 kg h−1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume
Sqrt{shat}_{min} resurrected
We discuss the use of the variable sqrt{shat}_{min}, which has been proposed
in order to measure the hard scale of a multi parton final state event using
inclusive quantities only, on a SUSY data sample for a 14 TeV LHC. In its
original version, where this variable was proposed on calorimeter level, the
direct correlation to the hard scattering scale does not survive when effects
from soft physics are taken into account. We here show that when using
reconstructed objects instead of calorimeter energy and momenta as input, we
manage to actually recover this correlation for the parameter point considered
here. We furthermore discuss the effect of including W + jets and t tbar+jets
background in our analysis and the use of sqrt{shat}_{min} for the suppression
of SM induced background in new physics searches.Comment: 23 pages, 9 figures; v2: 1 figure, several subsections and references
as well as new author affiliation added. Corresponds to published versio
A Quantum Mechanical Model of Spherical Supermembranes
We present a quantum mechanical model of spherical supermembranes. Using
superfields to represent the cartesian coordinates of the membrane, we are able
to exactly determine its supersymmetric vacua. We find there are two classical
vacua, one corresponding to an extended membrane and one corresponding to a
point-like membrane. For the case, instanton effects then
lift these vacua to massive states. For the case, there is
no instanton tunneling, and the vacua remain massless. Similarities to
spherical supermembranes as giant gravitons and in Matrix theory on pp-waves is
discussed.Comment: 9 page
Existence and stability of viscoelastic shock profiles
We investigate existence and stability of viscoelastic shock profiles for a
class of planar models including the incompressible shear case studied by
Antman and Malek-Madani. We establish that the resulting equations fall into
the class of symmetrizable hyperbolic--parabolic systems, hence spectral
stability implies linearized and nonlinear stability with sharp rates of decay.
The new contributions are treatment of the compressible case, formulation of a
rigorous nonlinear stability theory, including verification of stability of
small-amplitude Lax shocks, and the systematic incorporation in our
investigations of numerical Evans function computations determining stability
of large-amplitude and or nonclassical type shock profiles.Comment: 43 pages, 12 figure
The random case of Conley's theorem: III. Random semiflow case and Morse decomposition
In the first part of this paper, we generalize the results of the author
\cite{Liu,Liu2} from the random flow case to the random semiflow case, i.e. we
obtain Conley decomposition theorem for infinite dimensional random dynamical
systems. In the second part, by introducing the backward orbit for random
semiflow, we are able to decompose invariant random compact set (e.g. global
random attractor) into random Morse sets and connecting orbits between them,
which generalizes the Morse decomposition of invariant sets originated from
Conley \cite{Con} to the random semiflow setting and gives the positive answer
to an open problem put forward by Caraballo and Langa \cite{CL}.Comment: 21 pages, no figur
Precision measurements of large scale structure with future type Ia supernova surveys
Type Ia supernovae are currently the best known standard candles at
cosmological distances. In addition to providing a powerful probe of dark
energy they are an ideal source of information about the peculiar velocity
field of the local universe. Even with the very small number of supernovae
presently available it has been possible to measure the dipole and quadrupole
of the local velocity field out to z~0.025. With future continuous all-sky
surveys like the LSST project the luminosity distances of tens of thousands of
nearby supernovae will be measured accurately. This will allow for a
determination of the local velocity structure of the universe as a function of
redshift with unprecedented accuracy, provided the redshifts of the host
galaxies are known. Using catalogues of mock surveys we estimate that future
low redshift supernova surveys will be able to probe sigma-8 to a precision of
roughly 5% at 95% C.L. This is comparable to the precision in future galaxy and
weak lensing surveys and with a relatively modest observational effort it will
provide a crucial cross-check on future measurements of the matter power
spectrum.Comment: 18 pages, 9 figures, submitted to JCA
Discovery of a Multiply Lensed Submillimeter Galaxy in Early HerMES Herschel/SPIRE Data
We report the discovery of a bright (f(250 μm)>400 mJy), multiply lensed submillimeter galaxy HERMES J105751.1+573027 in Herschel/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880 μm Submillimeter Array observations resolve at least four images with a large separation of ~9". A high-resolution adaptive optics K_p image with Keck/NIRC2 clearly shows strong lensing arcs. Follow-up spectroscopy gives a redshift of z = 2.9575, and the lensing model gives a total magnification of μ ~ 11 ± 1. The large image separation allows us to study the multi-wavelength spectral energy distribution (SED) of the lensed source unobscured by the central lensing mass. The far-IR/millimeter-wave SED is well described by a modified blackbody fit with an unusually warm dust temperature, 88 ± 3 K. We derive a lensing-corrected total IR luminosity of (1.43 ± 0.09) × 10^(13) L_☉, implying a star formation rate of ~2500 M_☉ yr^(–1). However, models primarily developed from brighter galaxies selected at longer wavelengths are a poor fit to the full optical-to-millimeter SED. A number of other strongly lensed systems have already been discovered in early Herschel data, and many more are expected as additional data are collected
- …