73,196 research outputs found
Time and dark matter from the conformal symmetries of Euclidean space
The quotient of the conformal group of Euclidean 4-space by its Weyl subgroup
results in a geometry possessing many of the properties of relativistic phase
space, including both a natural symplectic form and non-degenerate Killing
metric. We show that the general solution posesses orthogonal Lagrangian
submanifolds, with the induced metric and the spin connection on the
submanifolds necessarily Lorentzian, despite the Euclidean starting pont. By
examining the structure equations of the biconformal space in an orthonormal
frame adapted to its phase space properties, we also find that two new tensor
fields exist in this geometry, not present in Riemannian geometry. The first is
a combination of the Weyl vector with the scale factor on the metric, and
determines the timelike directions on the submanifolds. The second comes from
the components of the spin connection, symmetric with respect to the new
metric. Though this field comes from the spin connection it transforms
homogeneously. Finally, we show that in the absence of conformal curvature or
sources, the configuration space has geometric terms equivalent to a perfect
fluid and a cosmological constant.Comment: 26 pages, no figures. Appreciable introductory material added.
Results substantially strengthened and explained. New results concerning dark
matter and dark energy candidates added to this versio
PROBABILISTIC COST EFFECTIVENESS IN AGRICULTURAL NONPOINT POLLUTION CONTROL
Conceptual weaknesses in the use of costs of average abatement as a measure of the cost effectiveness of agricultural nonpoint pollution control are examined. A probabilistic alternative is developed. The focus is on methods for evaluating whole-farm pollution control plans rather than individual practices. As a consequence, the analysis is presented in a chance-constrained activity analysis framework because activity procedures are a practical and well developed device for screening farm planes. Reliability of control is shown to be as important as reduction targets in designing farm plans for pollution control. Furthermore, broad-axe prescriptions of technology in the form of Best Management Practices may perform poorly with respect to cost effectiveness.Environmental Economics and Policy,
The Hierarchy Solution to the LHC Inverse Problem
Supersymmetric (SUSY) models, even those described by relatively few
parameters, generically allow many possible SUSY particle (sparticle) mass
hierarchies. As the sparticle mass hierarchy determines, to a great extent, the
collider phenomenology of a model, the enumeration of these hierarchies is of
the utmost importance. We therefore provide a readily generalizable procedure
for determining the number of sparticle mass hierarchies in a given SUSY model.
As an application, we analyze the gravity-mediated SUSY breaking scenario with
various combinations of GUT-scale boundary conditions involving different
levels of universality among the gaugino and scalar masses. For each of the
eight considered models, we provide the complete list of forbidden hierarchies
in a compact form. Our main result is that the complete (typically rather
large) set of forbidden hierarchies among the eight sparticles considered in
this analysis can be fully specified by just a few forbidden relations
involving much smaller subsets of sparticles.Comment: 44 pages, 2 figures. Python code providing lists of allowed and
forbidden hierarchy is included in ancillary file
Loading and testing a light scattering cell with a binary fluid mixture near its critical composition
Critical phenomena has been the subject of physics research for many years. However, only in recent years has the research effort become intense. The current intensity has caused the study of critical phenomena to be grouped into a previous older era and a present contemporary era. Turbidity cell filling with methanol cyclohexane is one of the first steps toward a further understanding of critical phenomena. Work performed during the research period is outlined. During this period, research was spent developing apparatus and techniques that will make it possible to study critical phenomena through turbidity measurements on methanol cyclohexane. Topics covered range from the orientation of turbidity cell parts for assembly to the filling apparatus and procedure used when th cell is built. The last section will briefly cover some of the observations made when viewing the cell in a controlled water bath. However, before mention is made of the specifics of the summer research, a short introduction to critical phenomena and turbidity and how they relate to this experiment is provided
Edge Detecting New Physics the Voronoi Way
We point out that interesting features in high energy physics data can be
determined from properties of Voronoi tessellations of the relevant phase
space. For illustration, we focus on the detection of kinematic "edges" in two
dimensions, which may signal physics beyond the standard model. After deriving
some useful geometric results for Voronoi tessellations on perfect grids, we
propose several algorithms for tagging the Voronoi cells in the vicinity of
kinematic edges in real data. We show that the efficiency is improved by the
addition of a few Voronoi relaxation steps via Lloyd's method. By preserving
the maximum spatial resolution of the data, Voronoi methods can be a valuable
addition to the data analysis toolkit at the LHC.Comment: 6 pages, 7 figure
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