2,435 research outputs found
Political Reforms and Public Policies: Evidence from Agricultural Protection.
This paper studies the effect of political regime transitions on public policy using a dataset on global agricultural distortions over 50 years (including data from 74 developing and developed countries over the period 1955-2005). We employ both difference-in-differences regressions and semi-parametric matching methods, exploiting the time series and cross-sectional variation in the data. Our semi-parametric estimates show that parametric methods might underestimate the effect of democracy on public policy. In addition, we find that the effect is asymmetric: agricultural protection increases after a countryâs transition to democracy of about 9% points, but there is no effect when the political regime shifts from democracy to autocracy. Overall, the evidence supports the redistributive nature of democratic institutions toward the majority and, therefore, it is consistent with the median voter model of political behaviour.
On the one-loop Kahler potential in five-dimensional brane-world supergravity
We present an on-shell formulation of 5d gauged supergravity coupled to
chiral matter multiplets localized at the orbifold fixed points. The brane
action is constructed via the Noether method. In such set-up we compute
one-loop corrections to the Kahler potential of the effective 4d supergravity
and compare the result with previous computations based on the off-shell
formalism. The results agree at lowest order in brane sources, however at
higher order there are differences. We explain this discrepancy by an ambiguity
in resolving singularities associated with the presence of infinitely thin
branes.Comment: 20 page
Electroweak Precision Observables and the Unhiggs
We compute one-loop corrections to the S and T parameters in the Unhiggs
scenario. In that scenario, the Standard Model Higgs is replaced by a non-local
object, called the Unhiggs, whose spectral function displays a continuum above
the mass gap. The Unhiggs propagator has effectively the same UV properties as
the Standard Model Higgs propagator, which implies that loop corrections to the
electroweak precision observables are finite and calculable. We show that the
Unhiggs is consistent with electroweak precision tests when its mass gap is at
the weak scale; in fact, it then mimics a light SM Higgs boson. We also argue
that the Unhiggs, while being perfectly visible to electroweak precision
observables, is invisible to detection at LEP.Comment: 13 pages; v2: references added, discussion of production
cross-section expande
Chaotic inflation in Jordan frame supergravity
We consider the inflationary scenario with non-minimal coupling in 4D Jordan
frame supergravity. We find that there occurs a tachyonic instability along the
direction of the accompanying non-inflaton field in generic Jordan frame
supergravity models. We propose a higher order correction to the Jordan frame
function for solving the tachyonic mass problem and show that the necessary
correction can be naturally generated by the heavy thresholds without spoiling
the slow-roll conditions. We discuss the implication of the result on the Higgs
inflation in NMSSM.Comment: 16 pages, no figures, version to be published in JCA
Electroweak observables in a general 5D background
Warped extra dimensions provide a new playground to study electroweak brea-king and the nature of the higgs field. In this paper we reanalyze the electroweak observables in theories with one extra dimension and a completely general warp factor. We demonstrate that, regardless of the 5D background, SU(2)_R is needed in order to avoid excessive contributions to the T parameter. For higgsless theories cancelations between different contributions to the S parameter are needed
FIRe glider: Mapping in situ chlorophyll variable fluorescence with autonomous underwater gliders
Nutrient and light availability regulate phytoplankton physiology and photosynthesis in the ocean. These physiological processes are difficult to sample in time and space over physiologically and ecologically relevant scales using traditional shipboard techniques. Gliders are changing the nature of data collection, by allowing a sustained presence at sea over regional scales, collecting data at resolution not possible using traditional techniques. The integration of a fluorescence induction and relaxation (FIRe) sensor in a Slocum glider allows autonomous highâresolution and verticallyâresolved measurements of photosynthetic physiological variables together with oceanographic data. In situ measurements of variable fluorescence under ambient light allows a better understanding of the physical controls of primary production (PP). We demonstrate this capability in a laboratory setting and with several glider deployments in the Southern Ocean. Development of these approaches will allow for the in situ evaluation of phytoplankton light stress and photoacclimation mechanisms, as well as the role of vertical mixing in phytoplankton dynamics and the underlying physiology, especially in remote locations and for prolonged duration
Constraints for the existence of flat and stable non-supersymmetric vacua in supergravity
We further develop on the study of the conditions for the existence of
locally stable non-supersymmetric vacua with vanishing cosmological constant in
supergravity models involving only chiral superfields. Starting from the two
necessary conditions for flatness and stability derived in a previous paper
(which involve the Kahler metric and its Riemann tensor contracted with the
supersymmetry breaking auxiliary fields) we show that the implications of these
constraints can be worked out exactly not only for factorizable scalar
manifolds, but also for symmetric coset manifolds. In both cases, the
conditions imply a strong restriction on the Kahler geometry and constrain the
vector of auxiliary fields defining the Goldstino direction to lie in a certain
cone. We then apply these results to the various homogeneous coset manifolds
spanned by the moduli and untwisted matter fields arising in string
compactifications, and discuss their implications. Finally, we also discuss
what can be said for completely arbitrary scalar manifolds, and derive in this
more general case some explicit but weaker restrictions on the Kahler geometry.Comment: 22 pages, Latex, no figure
Supersymmetry Breaking and Moduli Stabilization with Anomalous U(1) Gauge Symmetry
We examine the effects of anomalous U(1)_A gauge symmetry on soft
supersymmetry breaking terms while incorporating the stabilization of the
modulus-axion multiplet responsible for the Green-Schwarz (GS) anomaly
cancellation mechanism. In case of the KKLT stabilization of the GS modulus,
soft terms are determined by the GS modulus mediation, the anomaly mediation
and the U(1)_A mediation which are generically comparable to each other,
thereby yielding the mirage mediation pattern of superparticle masses at low
energy scale. Independently of the mechanism of moduli stabilization and
supersymmetry breaking, the U(1)_A D-term potential can not be an uplifting
potential for de Sitter vacuum when the gravitino mass is smaller than the
Planck scale by many orders of magnitude. We also discuss some features of the
supersymmetry breaking by red-shifted anti-brane which is a key element of the
KKLT moduli stabilization.Comment: 32 pages; references are adde
Holography, Pade Approximants and Deconstruction
We investigate the relation between holographic calculations in 5D and the
Migdal approach to correlation functions in large N theories. The latter
employs Pade approximation to extrapolate short distance correlation functions
to large distances. We make the Migdal/5D relation more precise by quantifying
the correspondence between Pade approximation and the background and boundary
conditions in 5D. We also establish a connection between the Migdal approach
and the models of deconstructed dimensions.Comment: 28 page
Soft-Wall Stabilization
We propose a general class of five-dimensional soft-wall models with AdS
metric near the ultraviolet brane and four-dimensional Poincar\'e invariance,
where the infrared scale is determined dynamically. A large UV/IR hierarchy can
be generated without any fine-tuning, thus solving the electroweak/Planck scale
hierarchy problem. Generically, the spectrum of fluctuations is discrete with a
level spacing (mass gap) provided by the inverse length of the wall, similar to
RS1 models with Standard Model fields propagating in the bulk. Moreover two
particularly interesting cases arise. They can describe: (a) a theory with a
continuous spectrum above the mass gap which can model unparticles
corresponding to operators of a CFT where the conformal symmetry is broken by a
mass gap, and; (b) a theory with a discrete spectrum provided by linear Regge
trajectories as in AdS/QCD models.Comment: 27 pages, 6 figures, 1 table. v2: references added, version to appear
in NJP Focus Issue on Extra Dimension
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