238 research outputs found
Rigidly Supersymmetric Gauge Theories on Curved Superspace
In this note we construct rigidly supersymmetric gauged sigma models and
gauge theories on certain Einstein four-manifolds, and discuss constraints on
these theories. In work elsewhere, it was recently shown that on some
nontrivial Einstein four-manifolds such as AdS, N=1 rigidly supersymmetric
sigma models are constrained to have target spaces with exact K\"ahler forms.
Similarly, in gauged sigma models and gauge theories, we find that
supersymmetry imposes constraints on Fayet-Iliopoulos parameters, which have
the effect of enforcing that K\"ahler forms on quotient spaces be exact. We
also discuss general aspects of universality classes of gauged sigma models, as
encoded by stacks, and also discuss affine bundle structures implicit in these
constructions.Comment: 23 pages; references added; more discussion added; v4: typos fixe
Positivity Constraints on Anomalies in Supersymmetric Gauge Theories
The relation between the trace and R-current anomalies in supersymmetric
theories implies that the U, U and U anomalies which
are matched in studies of N=1 Seiberg duality satisfy positivity constraints.
Some constraints are rigorous and others conjectured as four-dimensional
generalizations of the Zamolodchikov -theorem. These constraints are tested
in a large number of N=1 supersymmetric gauge theories in the non-Abelian
Coulomb phase, and they are satisfied in all renormalizable models with unique
anomaly-free R-current, including those with accidental symmetry. Most striking
is the fact that the flow of the Euler anomaly coefficient, , is
always positive, as conjectured by Cardy.Comment: latex, 36 page
Flavor Mediation Delivers Natural SUSY
If supersymmetry (SUSY) solves the hierarchy problem, then naturalness
considerations coupled with recent LHC bounds require non-trivial superpartner
flavor structures. Such "Natural SUSY" models exhibit a large mass hierarchy
between scalars of the third and first two generations as well as degeneracy
(or alignment) among the first two generations. In this work, we show how this
specific beyond the standard model (SM) flavor structure can be tied directly
to SM flavor via "Flavor Mediation". The SM contains an anomaly-free SU(3)
flavor symmetry, broken only by Yukawa couplings. By gauging this flavor
symmetry in addition to SM gauge symmetries, we can mediate SUSY breaking via
(Higgsed) gauge mediation. This automatically delivers a natural SUSY spectrum.
Third-generation scalar masses are suppressed due to the dominant breaking of
the flavor gauge symmetry in the top direction. More subtly, the
first-two-generation scalars remain highly degenerate due to a custodial U(2)
symmetry, where the SU(2) factor arises because SU(3) is rank two. This
custodial symmetry is broken only at order (m_c/m_t)^2. SUSY gauge coupling
unification predictions are preserved, since no new charged matter is
introduced, the SM gauge structure is unaltered, and the flavor symmetry treats
all matter multiplets equally. Moreover, the uniqueness of the anomaly-free
SU(3) flavor group makes possible a number of concrete predictions for the
superpartner spectrum.Comment: 17 pages, 7 figures, 2 tables. v2 references added, minor changes to
flavor constraints and a little discussion adde
The little flavons
Fermion masses and mixing matrices can be described in terms of spontaneously
broken (global or gauge) flavor symmetries. We propose a little-Higgs inspired
scenario in which an SU(2)xU(1) gauge flavor symmetry is spontaneously (and
completely) broken by the vacuum of the dynamically induced potential for two
scalar doublets (the flavons) which are pseudo-Goldstone bosons remaining after
the spontaneous breaking--at a scale between 10 and 100 TeV--of an approximate
SU(6) global symmetry. The vacuum expectation values of the flavons give rise
to the texture in the fermion mass matrices. We discuss in detail the case of
leptons. Light-neutrino masses arise by means of a see-saw-like mechanism that
takes place at the same scale at which the SU(6) global symmetry is broken. We
show that without any fine tuning of the parameters the experimental values of
the charged-lepton masses,the neutrino square mass differences and the
Pontecorvo-Maki-Nakagawa-Sakata mixing matrix are reproduced.Comment: 13 pages, revTeX4. Version to be published in PR
Body Size Measurements as Predictors of Type 2 Diabetes in Aboriginal People
OBJECTIVE: To investigate waist circumference, waist-to-hip ratio, body mass index (BMI), weight and hip circumference as risk factors for type 2 diabetes in Aboriginal Australians. DESIGN: Community-based cross-sectional study. SUBJECTS: In total, 915 Australian Aboriginal adults (age: 18-74 y) from a remote Aboriginal community in the Northern Territory of Australia. MEASUREMENTS: Body size measurements included waist circumference, waist-to-hip ratio, BMI, weight and hip circumference. Diabetes status was determined according to medical history and fasting and 2-h postload plasma glucose values. Logistic regression was used to calculate odds ratio for diabetes associated with 1 standard deviation (s.d.) increase in a body size measurement. The areas under the ROC curves of five body size measurements were calculated and compared. RESULTS: Risk of diabetes increased with increasing levels of body size. ORs (95% CI) for diabetes with adjustment for age and sex were 2.16 (1.75, 2.66), 1.80 (1.49, 2.17), 1.41 (1.17, 1.71), 1.81 (1.51, 2.19) and 1.84 (1.50, 2.24) associated with 1 s.d. increase in waist circumference, BMI, weight, waist-to-hip ratio, and hip circumference, respectively. The area under the ROC curve for waist circumference was significantly higher than those for other measurements. CONCLUSION: Waist circumference is the best body size measurement in predicting diabetes in Aboriginal people
Constraining Proton Lifetime in SO(10) with Stabilized Doublet-Triplet Splitting
We present a class of realistic unified models based on supersymmetric SO(10)
wherein issues related to natural doublet-triplet (DT) splitting are fully
resolved. Using a minimal set of low dimensional Higgs fields which includes a
single adjoint, we show that the Dimopoulos--Wilzcek mechanism for DT splitting
can be made stable in the presence of all higher order operators without having
pseudo-Goldstone bosons and flat directions. The \mu term of order TeV is found
to be naturally induced. A Z_2-assisted anomalous U(1)_A gauge symmetry plays a
crucial role in achieving these results. The threshold corrections to
alpha_3(M_Z), somewhat surprisingly, are found to be controlled by only a few
effective parameters. This leads to a very predictive scenario for proton
decay. As a novel feature, we find an interesting correlation between the d=6
(p\to e^+\pi^0) and d=5 (p\to \nu-bar K+) decay amplitudes which allows us to
derive a constrained upper limit on the inverse rate of the e^+\pi^0 mode. Our
results show that both modes should be observed with an improvement in the
current sensitivity by about a factor of five to ten.Comment: 21 pages LaTeX, 2 figures, Few explanatory sentences and three new
references added, minor typos corrected
Model for fermion mass matrices and the origin of quark-lepton symmetry
Several phenomenological features of fermion masses and mixings can be
accounted for by a simple model for fermion mass matrices, which suggests an
underlying U(2) horizontal symmetry. In this context, it is also proposed how
an approximate quark-lepton symmetry can be achieved without unified gauge
theories.Comment: 12 pages, RevTex. Minor changes, some references adde
HTAP_v2.2: a mosaic of regional and global emission grid maps for 2008 and 2010 to study hemispheric transport of air pollution
The mandate of the Task Force Hemispheric Transport of Air Pollution (TF HTAP) under the Convention on Long-Range Transboundary Air Pollution (CLRTAP) is to improve the scientific understanding of the intercontinental air pollution transport, to quantify impacts on human health, vegetation and climate, to identify emission mitigation options across the regions of the Northern Hemisphere, and to guide future policies on these aspects.
The harmonization and improvement of regional emission inventories is imperative to obtain consolidated estimates on the formation of global-scale air pollution. An emissions data set has been constructed using regional emission grid maps (annual and monthly) for SO2, NOx, CO, NMVOC, NH3, PM10, PM2.5, BC and OC for the years 2008 and 2010, with the purpose of providing consistent information to global and regional scale modelling efforts.
This compilation of different regional gridded inventories - including that of the Environmental Protection Agency (EPA) for USA, the EPA and Environment Canada (for Canada), the European Monitoring and Evaluation Programme (EMEP) and Netherlands Organisation for Applied Scientific Research (TNO) for Europe, and the Model Inter-comparison Study for Asia (MICS-Asia III) for China, India and other Asian countries - was gap-filled with the emission grid maps of the Emissions Database for Global Atmospheric Research (EDGARv4.3) for the rest of the world (mainly South America, Africa, Russia and Oceania). Emissions from seven main categories of human activities (power, industry, residential, agriculture, ground transport, aviation and shipping) were estimated and spatially distributed on a common grid of 0.1 degree W 0.1 degree longitude-latitude, to yield monthly, global, sector-specific grid maps for each substance and year.
The HTAP_v2.2 air pollutant grid maps are considered to combine latest available regional information within a complete global data set. The disaggregation by sectors, high spatial and temporal resolution and detailed information on the data sources and references used will provide the user the required transparency. Because HTAP_v2.2 contains primarily official and/or widely used regional emission grid maps, it can be recommended as a global baseline emission inventory, which is regionally accepted as a reference and from which different scenarios assessing emission reduction policies at a global scale could start.
An analysis of country-specific implied emission factors shows a large difference between industrialised countries and developing countries for acidifying gaseous air pollutant emissions (SO2 and NOx) from the energy and industry sectors. This is not observed for the particulate matter emissions (PM10, PM2.5), which show large differences between countries in the residential sector instead. The per capita emissions of all world countries, classified from low to high income, reveal an increase in level and in variation for gaseous acidifying pollutants, but not for aerosols. For aerosols, an opposite trend is apparent with higher per capita emissions of particulate matter for low income countries
Fermion Masses and Mixings in the Little Flavon Model
We present a complete analysis of the fermion masses and mixing matrices in
the framework of the little flavon model. In this model textures are generated
by coupling the fermions to scalar fields, the little flavons, that are
pseudo-Goldstone bosons of the breaking of a global SU(6) symmetry. The Yukawa
couplings arise from the vacuum expectation values of the flavon fields, their
sizes controlled by a potential a la Coleman-Weinberg. Quark and lepton mass
hierarchies and mixing angles are accomodated within the effective approach in
a natural manner.Comment: 11 pages, RevTeX4, version to appear on Phys. Rev.
Dynamical Supersymmetry Breaking
Supersymmetry is one of the most plausible and theoretically motivated
frameworks for extending the Standard Model. However, any supersymmetry in
Nature must be a broken symmetry. Dynamical supersymmetry breaking (DSB) is an
attractive idea for incorporating supersymmetry into a successful description
of Nature. The study of DSB has recently enjoyed dramatic progress, fueled by
advances in our understanding of the dynamics of supersymmetric field theories.
These advances have allowed for direct analysis of DSB in strongly coupled
theories, and for the discovery of new DSB theories, some of which contradict
early criteria for DSB. We review these criteria, emphasizing recently
discovered exceptions. We also describe, through many examples, various
techniques for directly establishing DSB by studying the infrared theory,
including both older techniques in regions of weak coupling, and new techniques
in regions of strong coupling. Finally, we present a list of representative DSB
models, their main properties, and the relations between them.Comment: 113 pages, Revtex. Minor changes, references added and corrected. To
appear in Reviews of Modern Physic
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