591 research outputs found
Housing prices and multiple employment nodes: is the relationship nonmonotonic?
Standard urban economic theory predicts that house prices will decline with distance from the central business district. Empirical results have been equivocal, however. Disjoints between theory and empirics may be due to a nonmonotonic relationship between house prices and access to employment arising from the negative externalities associated with proximity to multiple centres of employment. Based on data from Glasgow (Scotland), we use gravity-based measures of accessibility estimated using a flexible functional form that allows for nonmonotonicity. The results are thoroughly tested using recent advances in spatial econometrics. We find compelling evidence of a nonmonotonic effect in the accessibility measure and discuss the implications for planning and housing policy
Determining masses of supersymmetric particles
If supersymmetric particles are produced at the Large Hadron Collider it
becomes very important not only to identify them, but also to determine their
masses with the highest possible precision, since this may lead to an
understanding of the SUSY-breaking mechanism and the physics at some higher
scale. We here report on studies of how such mass measurements are obtained,
and how the precision can be optimized.Comment: 11 pages, contribution to the proceedings "II. Southeastern European
Workshop Challenges Beyond The Standard Model", 19-23 May 2005, Vrnjacka
Banja, Serbi
Resolving ambiguities in mass determinations at future colliders
The measurements of kinematical endpoints, in cascade decays of
supersymmetric particles, in principle allow for a determination of the masses
of the unstable particles. However, in this procedure ambiguities often arise.
We here illustrate how such ambiguities arise. They can be resolved by a
precise determination of the LSP mass, provided by the Linear Collider.Comment: 6 pages, 6 figures, to appear in the proceedings of the 2005
International Linear Collider Workshop, Stanford, U.S.
Mass Determination in Cascade Decays Using Shape Formulas
In SUSY scenarios with invisible LSP, sparticle masses can be determined from
fits to the endpoints of invariant mass distributions. Here we discuss possible
improvements by using the shapes of the distributions. Positive results are
found for multiple-minima situations and for mass regions where the endpoints
do not contain sufficient information to obtain the masses.Comment: to appear in Proceedings of SUSY06, the 14th International Conference
on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine,
California, 12-17 June 200
Mass ambiguities in cascade decays
We review the use of invariant mass distributions in cascade decays to
measure the masses of New Physics (NP) particles in scenarios where the final
NP cascade particle is invisible. We extend earlier work by exploring further
the problem of multiple solutions for the masses.Comment: 4 pages, 4 figures, to appear in the proceedings of the XXXIII
International Conference on High Energy Physics (ICHEP'06), July 26 - August
2 2006, Mosco
Standard Model Parameters and the Cosmological Constant
Simple functional relations amongst standard model couplings, including
gravitional, are conjectured. Possible implications for cosmology and future
theory are discussed.Comment: submitted to Physical Review
Model-independent constraints on contact interactions from LEP2 data analysis
We derive model-independent constraints on four-fermion contact
interaction-type dynamics from the published preliminary LEP2 experimental data
on e^+e^- annihilation into \mu^+\mu^- and \tau^+\tau^- pairs, measured at
different energies between 130 and 207 GeV. The basic observables are chosen to
be the total cross section and the forward-backward asymmetry, and the analysis
realistically takes into account data uncertainties and correlations among
measurements at the various energies. The combination of data from different
energy points plays an important role in the determination of regions allowed
for the contact interaction coupling constants. In contrast to the more common
one-parameter analyses, we only obtain constraints on pairs of parameters
rather than limits on individual ones.Comment: 13 pages, LaTeX, including figures. v2: Included discussion of tau
data, version to appear in EPJ
Sneutrino Identification in Lepton Pair Production at ILC with Polarized Beams
Numerous non-standard dynamics are described by contact-like effective
interactions that can manifest themselves in electron-positron collisions only
through deviations of the observables (cross sections, asymmetries) from the
Standard Model predictions. If such a deviation were observed, it would be
important to identify the actual source among the possible non-standard
interactions as many different new physics scenarios may lead to very similar
experimental signatures. We study the possibility of uniquely identifying the
indirect effects of s-channel sneutrino exchange, as predicted by
supersymmetric theories with R-parity violation, against other new physics
scenarios in high-energy e^+e^- annihilation into lepton pairs at the
International Linear Collider. These competitive models are interactions based
on gravity in large and in TeV-scale extra dimensions, anomalous gauge
couplings, Z' vector bosons and compositeness-inspired four-fermion contact
interactions. To evaluate the identification reach on sneutrino exchange, we
use as basic observable a double polarization asymmetry, that is particularly
suitable to directly test for such s-channel sneutrino exchange effects in the
data analysis. The availability of both beams being polarized plays a crucial
role in identifying the new physics scenario.Comment: 10 pages, 3 figure
Identification of extra neutral gauge bosons at the International Linear Collider
Heavy neutral gauge bosons, Z's, are predicted by many theoretical schemes of
physics beyond the Standard Model, and intensive searches for their signatures
will be performed at present and future high energy colliders. It is quite
possible that Z's are heavy enough to lie beyond the discovery reach expected
at the CERN Large Hadron Collider LHC, in which case only indirect signatures
of Z' exchanges may occur at future colliders, through deviations of the
measured cross sections from the Standard Model predictions. We here discuss in
this context the foreseeable sensitivity to Z's of fermion-pair production
cross sections at an e^+e^- linear collider, especially as regards the
potential of distinguishing different Z' models once such deviations are
observed. Specifically, we assess the discovery and identification reaches on
Z' gauge bosons pertinent to the E_6, LR, ALR and SSM classes of models, that
should be attained at the planned International Linear Collider (ILC). With the
high experimental accuracies expected at the ILC, the discovery and the
identification reaches on the Z' models under consideration could be increased
substantially. In particular, the identification among the different models
could be achieved for values of Z' masses in the discovery (but beyond the
identification) reach of the LHC. An important role in enhancing such reaches
is played by the electron (and possibly the positron) longitudinally polarized
beams. Also, although the purely leptonic processes are experimentally cleaner,
the measurements of c- and b-quark pair production cross sections are found to
carry important, and complementary, information on these searches.Comment: 21 page
On-farm food loss in northern and central California: Results of field survey measurementsAuthor links open overlay panel
Prevailing estimates of food loss at the farm level are sparse and often reliant upon grower surveys. A more comprehensive review of food loss at the farm level using field surveys is required to gain an adequate understanding of the depth of this issue. This paper details the results of 123 in-field surveys and 18 in-depth interviews of 20 different, hand-harvested field crops performed largely on midsize to large conventional farms in northern and central California. We also provide estimates of the percentage of fields that go unharvested, commonly known as walk-by fields. The results show that food loss is highly variable and largely dependent upon the crop, variety, market price, labor costs, grower practices, buyer specifications, and environmental conditions. On average, we found 11,299 kg/ha of food loss at the farm level, which equates to 31.3% of the marketed yield. When walk-by losses are included, this figure rises to 33.7%. Our paper also demonstrates that grower estimates are typically very unreliable for estimating on-farm food losses. Actual, measured edible food loss exceeded growers’ estimates by a median value of 157%. Strategies to utilize this lost produce could play a significant role in reducing the impact of agriculture on the environment and providing food for the rapidly growing population
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