2,849 research outputs found
Phase structure of the N=1 supersymmetric Yang-Mills theory at finite temperature
Supersymmetry (SUSY) has been proposed to be a central concept for the
physics beyond the standard model and for a description of the strong
interactions in the context of the AdS/CFT correspondence. A deeper
understanding of these developments requires the knowledge of the properties of
supersymmetric models at finite temperatures. We present a Monte Carlo
investigation of the finite temperature phase diagram of the N=1 supersymmetric
Yang-Mills theory (SYM) regularised on a space-time lattice. The model is in
many aspects similar to QCD: quark confinement and fermion condensation occur
in the low temperature regime of both theories. A comparison to QCD is
therefore possible. The simulations show that for N=1 SYM the deconfinement
temperature has a mild dependence on the fermion mass. The analysis of the
chiral condensate susceptibility supports the possibility that chiral symmetry
is restored near the deconfinement phase transition.Comment: 26 pages, 12 figure
PeV-Scale Supersymmetry
Although supersymmetry has not been seen directly by experiment, there are
powerful physics reasons to suspect that it should be an ingredient of nature
and that superpartner masses should be somewhat near the weak scale. I present
an argument that if we dismiss our ordinary intuition of finetuning, and focus
entirely on more concrete physics issues, the PeV scale might be the best place
for supersymmetry. PeV-scale supersymmetry admits gauge coupling unification,
predicts a Higgs mass between 125 GeV and 155 GeV, and generally disallows
flavor changing neutral currents and CP violating effects in conflict with
current experiment. The PeV scale is motivated independently by dark matter and
neutrino mass considerations.Comment: 5 RevTex page
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Behaviour change at work: Empowering energy efficiency in the workplace through user-centred design
Copyright @ 2011 University of California eScholarship RepositoryCO2 emissions from non-domestic buildings - primarily workplaces - make up 18 percent of the UK's carbon footprint. A combination of technology advances and behavioural changes have the potential to make significant impact, but interventions have often been planned in ways which do not take into account the needs, levels of understanding and everyday behavioural contexts of building users - and hence do not achieve the hoped-for success.This paper provides a brief introduction to the Empower project, a current industrial-academic collaboration in the UK which is applying methods from user-centred design practice to understand diverse users' needs, priorities, mental models of energy and decision-making heuristics - as well as the affordances available to them - in a number of office buildings. We are developing and trialling a set of low-cost, simple software interventions tailored to multiple user groups with different degrees of agency over their energy use, which seek to influence more energy efficient behaviour at work in areas such as HVAC, lighting and equipment use. The project comprises an ethnographic research phase, a participatory design programme involving building users in the design of interventions, and iterative trials in a large office building in central London
Implications of gauge-mediated supersymmetry breaking with vector-like quarks and a ~125 GeV Higgs boson
We investigate the implications of models that achieve a Standard Model-like
Higgs boson of mass near 125 GeV by introducing additional TeV-scale
supermultiplets in the vector-like 10+\bar{10} representation of SU(5), within
the context of gauge-mediated supersymmetry breaking. We study the resulting
mass spectrum of superpartners, comparing and contrasting to the usual
gauge-mediated and CMSSM scenarios, and discuss implications for LHC
supersymmetry searches. This approach implies that exotic vector-like fermions
t'_{1,2}, b',and \tau' should be within the reach of the LHC. We discuss the
masses, the couplings to electroweak bosons, and the decay branching ratios of
the exotic fermions, with and without various unification assumptions for the
mass and mixing parameters. We comment on LHC prospects for discovery of the
exotic fermion states, both for decays that are prompt and non-prompt on
detector-crossing time scales.Comment: 32 pages. v2: references added, figure caption 5.3 correcte
Late Reheating, Hadronic Jets and Baryogenesis
If inflaton couples very weakly to ordinary matter the reheating temperature
of the universe can be lower than the electroweak scale. In this letter we show
that the late reheating occurs in a highly non-uniform way, within narrow areas
along the jets produced by ordinary particles originated from inflaton decays.
Depending on inflaton mass and decay constant, the initial temperature inside
the lumps of the overheated plasma may be large enough to trigger the
unsuppressed sphaleron processes with baryon number non-conservation, allowing
for efficient local electroweak baryogenesis.Comment: 4 pages, 2 figures, revtex
The Minimal Model for Dark Matter and Unification
Gauge coupling unification and the success of TeV-scale weakly interacting
dark matter are usually taken as evidence of low energy supersymmetry (SUSY).
However, if we assume that the tuning of the higgs can be explained in some
unnatural way, from environmental considerations for example, SUSY is no longer
a necessary component of any Beyond the Standard Model theory. In this paper we
study the minimal model with a dark matter candidate and gauge coupling
unification. This consists of the SM plus fermions with the quantum numbers of
SUSY higgsinos, and a singlet. It predicts thermal dark matter with a mass that
can range from 100 GeV to around 2 TeV and generically gives rise to an
electric dipole moment that is just beyond current experimental limits, with a
large portion of its allowed parameter space accessible to next generation EDM
and direct detection experiments. We study precision unification in this model
by embedding it in a 5-D orbifold GUT where certain large threshold corrections
are calculable, achieving gauge coupling and b-tau unification, and predicting
a rate of proton decay just beyond current limits.Comment: 20 pages, 10 figures. v2: Minor typos and Reference errors corrected.
Modified explanation of the KK mode contribution to runnin
On the Theory of Fermionic Preheating
In inflationary cosmology, the particles constituting the Universe are
created after inflation due to their interaction with moving inflaton field(s)
in the process of preheating. In the fermionic sector, the leading channel is
out-of equilibrium particle production in the non-perturbative regime of
parametric excitation, which respects Pauli blocking but differs significantly
from the perturbative expectation. We develop theory of fermionic preheating
coupling to the inflaton, without and with expansion of the universe, for light
and massive fermions, to calculate analytically the occupation number of
created fermions, focusing on their spectra and time evolution. In the case of
large resonant parameter we extend for rermions the method of successive
parabolic scattering, earlier developed for bosonic preheating. In an expanding
universe parametric excitation of fermions is stochastic. Created fermions very
quickly, within tens of inflaton oscillations, fill up a sphere of radius
in monetum space. We extend our formalism to the production of
superheavy fermions and to `instant' fermion creation.Comment: 14 pages, latex, 12 figures, submitted for publicatio
Modification of GLEAMS for Modeling Movement of Organic Contaminants from Land-Applied Biosolids
Municipal biosolids are commonly applied to agricultural lands as fertilizer, but this also poses potential risks to groundwater and surface water quality from constituents that may be mobilized during storm events. In the present study, an existing model, Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), is modified to predict the fate and transport of organic contaminants from land-applied biosolids, primarily via addition of a labile biosolids organic carbon phase distinct from soil organic carbon. While capable of simulating contaminant transport in runoff and via percolation, only the runoff portion of the model was able to be calibrated using existing experimental data, and showed good agreement with field runoff data for acetaminophen, ibuprofen, triclosan, triclocarban, and estrone, but substantially under-predicted concentrations for carbamazepine, androstenedione, and progesterone. The model is applied to various scenarios using varied chemical properties, application date in the arid west, and application method (i.e., surface spreading vs. incorporation). Chemicals with longer half-lives and lower KOCs exhibited higher losses in runoff than chemicals with shorter half-lives and higher KOCs. For short half-life chemicals (i.e., ≤100 days), application at the beginning of the dry season resulted in the lowest losses. However, for long half-life chemicals (∼1000 days) with high KOC (10,000–100,000), application during the rainy season resulted in the lowest losses, because this caused organic carbon to be high during the period of highest runoff. While further work is necessary to calibrate the percolation and subsurface transport portion, the model can help predict environmental risk from land-application of biosolids, highlight gaps in our knowledge about how chemicals are mobilized and transported from biosolids, and help identify management practices that result in minimal impacts to water quality
Electron electric dipole moment experiment using electric-field quantized slow cesium atoms
A proof-of-principle electron electric dipole moment (e-EDM) experiment using
slow cesium atoms, nulled magnetic fields, and electric field quantization has
been performed. With the ambient magnetic fields seen by the atoms reduced to
less than 200 pT, an electric field of 6 MV/m lifts the degeneracy between
states of unequal mF and, along with the low (approximately 3 m/s) velocity,
suppresses the systematic effect from the motional magnetic field. The low
velocity and small residual magnetic field have made it possible to induce
transitions between states and to perform state preparation, analysis, and
detection in regions free of applied static magnetic and electric fields. This
experiment demonstrates techniques that may be used to improve the e-EDM limit
by two orders of magnitude, but it is not in itself a sensitive e-EDM search,
mostly due to limitations of the laser system.Comment: 9 pages, 8 figures, accepted for publication in Phys. Rev.
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