3,408 research outputs found
International Finance in General Equilibrium
Our purpose in this paper is to unify international trade and finance in a single general equilibrium model. Our model is rich enough to include multiple commodities (including traded and nontraded goods), heterogeneous consumers in each country, multiple time periods, multiple credit markets, and multiple currencies. Yet our model is simple enough to be effectively computable. We explicitly calculate the financial and real effects of changes in tariffs, productivity, and preferences, as well as the effects of monetary and fiscal policy. We maintain agent optimization, rational expectations, and market clearing (i.e., perfect competition with flexible prices) throughout. But because of the important role money plays, and because of the heterogeneity of markets and agents, we find that fiscal and monetary policy both have real effects. The effects of policy on real income, long-term interest rates, and exchange rates are qualitatively identical to those suggested in Mundell-Fleming (without the small country hypothesis), although our equilibrating mechanisms are different. However, because the Mundell-Fleming model ignores expectations and relative price changes, our model predicts different effects on the flow of capital, the balance of trade, and real exchange rates in some circumstances.Currency, cash, fiscal policy, montary policy, money, trade
Designing the payout phase of funded pension pillars in central and eastern European countries
Over the past decade or so, most Central and Eastern European countries have reformed their pension systems, significantly downsizing their public pillars and creating private pillars based on capitalization accounts. Early policy attention was focused on the accumulation phase but several countries are now reaching the stage where they need to address the design of the payout phase. This paper reviews the complex policy issues that will confront policymakers in this effort and summarizes recent plans and developments in four countries (Poland, Hungary, Estonia, and Lithuania). The paper concludes by highlighting a number of options that merit detailed consideration.Debt Markets,Pensions&Retirement Systems,Financial Literacy,Insurance&Risk Mitigation,Investment and Investment Climate
A No-Scale Framework for Sub-Planckian Physics
We propose a minimal model framework for physics below the Planck scale with
the following features: (i) it is based on no-scale supergravity, as favoured
in many string compactifications, (ii) it incorporates Starobinsky-like
inflation, and hence is compatible with constraints from the Planck satellite,
(iii) the inflaton may be identified with a singlet field in a see-saw model
for neutrino masses, providing an efficient scenario for reheating and
leptogenesis, (iv) supersymmetry breaking occurs with an arbitrary scale and a
cosmological constant that vanishes before radiative corrections, (v) regions
of the model parameter space are compatible with all LHC, Higgs and dark matter
constraints.Comment: 6 pages, 2 figures, some minor corrections and additions. Final
versio
From Gravity to No-Scale Supergravity
We show that gravity coupled conformally to scalar fields is equivalent
to the real bosonic sector of SU(N,1)/SU(N)U(1) no-scale supergravity,
where the conformal factor can be identified with the K\"ahler potential, and
we review the construction of Starobinsky-like models of inflation within this
framework.Comment: 15 pages, version accepted for publicatio
Starobinsky-Like Inflation in Dilaton-Brane Cosmology
We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in
brane cosmology scenarios based on string theory, in which our universe is
represented as a three-brane. The effective potential may acquire a constant
term from a density of effectively point-like non-pertubative defects on the
brane. Higher-genus corrections generate corrections to the effective potential
that are exponentially damped at large field values, as in the Starobinsky
model, but at a faster rate, leading to a smaller prediction for the tensor-to
scalar perturbation ratio r. This may be compensated partially by logarithmic
deformations on the world-sheet due to recoil of the defects due to scattering
by string matter on the brane, which tend to enhance the tensor-to-scalar
ratio.Comment: 6 pages, 1 figure, Note Added to discuss BICEP2 data in connection
with the present class of stringy inflation models. References added. No
effect on conclusions other than the statement that D-particle fluctuations
may provide independent (from dilaton) sources of tensor perturbations that
enhance the tensor-to-scalar ratio in agreement with BICEP2 data. Version to
appear in Phys. Lett.
Starobinsky-like Inflationary Models as Avatars of No-Scale Supergravity
Models of cosmological inflation resembling the Starobinsky R + R^2 model
emerge naturally among the effective potentials derived from no-scale
SU(N,1)/SU(N) x U(1) supergravity when N > 1. We display several examples in
the SU(2,1)/SU(2) x U(1) case, in which the inflaton may be identified with
either a modulus field or a matter field. We discuss how the modulus field may
be stabilized in models in which a matter field plays the role of the inflaton.
We also discuss models that generalize the Starobinsky model but display
different relations between the tilt in the spectrum of scalar density
perturbations, n_s, the tensor-to-scalar ratio, r, and the number of e-folds,
N_*. Finally, we discuss how such models can be probed by present and future
CMB experiments.Comment: 23 pages, 3 figure
Algebras, Hawking Radiation and Information Retention by Stringy Black Holes
We have argued previously, based on the analysis of two-dimensional stringy
black holes, that information in stringy versions of four-dimensional
Schwarzschild black holes (whose singular regions are represented by
appropriate Wess-Zumino-Witten models) is retained by quantum -symmetries
when the horizon area is not preserved due to Hawking radiation. It is key that
the exactly-marginal conformal world-sheet operator representing a massless
stringy particle interacting with the black hole requires a contribution from
generators in its vertex function. The latter correspond to
delocalised, non-propagating, string excitations that guarantee the transfer of
information between the string black hole and external particles. When
infalling matter crosses the horizon, these topological states are excited via
a process: (Stringy black hole) + infalling matter (Stringy
black hole), where the black hole is viewed as a stringy state with a
specific configuration of charges that are conserved. Hawking
radiation is then the reverse process, with conservation of the
charges retaining information. The Hawking radiation spectrum near the horizon
of a Schwarzschild or Kerr black hole is specified by matrix elements of
higher-order currents that form a phase-space algebra. We show
that an appropriate gauging of this algebra preserves the horizon
two-dimensional area classically, as expected because the latter is a conserved
Noether charge.Comment: 21 pages, no figure
Comments on Graviton Propagation in Light of GW150914
The observation of gravitational waves from the Laser Interferometer
Gravitational-Wave Observatory (LIGO) event GW150914 may be used to constrain
the possibility of Lorentz violation in graviton propagation, and the
observation by the Fermi Gamma-Ray Burst Monitor of a transient source in
apparent coincidence may be used to constrain the difference between the
velocities of light and gravitational waves: .Comment: 9 pages, no figures; v2 contains additional description and a Noted
Added about constraints from GW15122
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