2,505 research outputs found
Dimensional reduction of the massless limit of the linearized "New Massive Gravity"
The so called "New Massive Gravity" in consists of the
Einstein-Hilbert action (with minus sign) plus a quadratic term in curvatures
(-term). Here we perform the Kaluza-Klein dimensional reduction of the
linearized -term to . We end up with a fourth-order massive
electrodynamics in described by a rank-2 tensor. Remarkably, there
appears a local symmetry in which persists even after gauging away the
Stueckelberg fields of the dimensional reduction. It plays the role of a
gauge symmetry. Although of higher-order in derivatives, the new massive
electrodynamics is ghost free, as we show here. It is shown, via master action,
to be dual to the Maxwell-Proca theory with a scalar Stueckelberg field.Comment: 12 pages, one more reference and text slightly modified accordingl
Is the US Fiscal Deficit Sustainable? A Fractionally Integrated and Cointegrated Approach
The sustainability of fiscal deficits has received in recent years increasing attention from economists. Empirical work has concentrated on both the univariate properties of debt and the cointegration properties of public revenues and expenditures. In this paper, we examine if sustainability of the US fiscal deficit holds by means of studying the univariate properties of the difference between public revenues and expenditures. However, instead of using classical approaches based on I(1) or I(0) integration techniques, we use a methodology based on fractional processes. The results show that the public deficit in the US is an I(d) process with d slightly smaller than 1, implying that fiscal deficit is mean reverting, and thus, sustainable, though the adjustment process towards equilibrium will take a very long time.
Additional Empirical Evidence on Real Convergence: A Fractionally Integrated Approach
This article examines the real convergence hypothesis in 15 OECD countries. For this purpose, we examine the order of integration of the real GDP per capita series in these countries as well as their differences with respect to the US which is used as a benchmark country. We use both parametric and semiparametric methods and the results show that convergence is only achieved in half of the countries, namely, Austria, Australia, Canada, Finland, Germany, Japan and the UK. On the contrary, the results for Belgium, Denmark, France, Italy, the Netherlands, Norway and Sweden show strong evidence against this hypothesis.
Fermionic dark matter-photon quantum interaction: A mechanism for darkness
ELKO fermionic fields are prime candidates to describe dark matter, due to
their intrinsic neutral nature, as they are constructed as eigenstates of the
charge conjugation operator with dual helicity. To formulate the meaning of the
darkness, the ELKO-photon coupling is scrutinized with a Pauli-like
interaction, and the path integral is then formulated from the phase space
constraint structure. Ward-Takahashi-like identities and Schwinger-Dyson
equations, together with renormalizability, are employed to investigate a
phenomenological mechanism to avoid external light signals. Accordingly, the
non-polarized pair annihilation and Compton-like processes are shown to vanish
at the limit of small scattering angles even if considering 1-loop radiative
corrections, reinforcing the ELKO dark matter interpretation. However, ELKO
interactions with nucleons are still possible. Motivated by recent
nucleon-recoil experiments to detect dark matter, we furnish a consistent
theoretical setup to describe ELKO-photon interaction compatible with the
prevalence of darkness.Comment: 42 pages, 6 figure
Time Series
This paper first shows that survey-based expectations (SBE) outperform standard time
series models in U.S. quarterly inflation out-of-sample prediction and that the term structure
of survey-based inflation forecasts has predictive power over the path of future inflation
changes. It then proposes some empirical explanations for the forecasting success
of survey-based inflation expectations. We show that SBE pool a large amount of heterogeneous
information on inflation expectations and react more flexibly and accurately
to macro conditions both contemporaneously and dynamically. We illustrate the flexibility
of SBE forecasts in the context of the recent financial crisis
Generalized Stueckelberg-Higgs gauge theories
The aim of this work is to discuss and explorer some generalized aspects of
generation of photon mass respecting gauge symmetry. So with this intention we
introduce the generalized Stueckelberg and Higgs gauge theories and present the
classical and quantum conceptual aspects. We construct the quantum theory by
writing the transition amplitude in the Fadeev-Senjanovic formalism and put it
in a covariant form by the Fadeev-Popov method. Posteriorly we analyze the
independence of physics by gauge choices via BRST symmetry. As we will see, the
Stueckelberg structure has influence in the quantization process of the Higgs
theory in the Gerardus 't Hooft shape, in which we see an intimate relationship
between the Stueckelberg compensating field and the Goldstone boson. The
degrees of freedom are explored not only in the quantization process, due to
the constraints in gauge theories, but also in the Goldstone theorem, wherein
we understand how the generalized gauge field eat the Goldstone boson and
acquire mass
Banksβ Net Interest Margin in the 2000s: A Macro-Accounting International Perspective
This paper re-examines the determinants of Net Interest Margin (NIM) in the banking industries
of 15 developed and emerging economies. It presents three main contributions
with respect to previous studies: first, we analyze the determinants of NIM in the years
leading to the 2008 financial crisis; second, we account for the role of different accounting
standards across countries; third, we use multi-way cluster estimation methodologies
which control for cross-sectional and time-series dependence in macroeconomic and
banking variables. We find that the introduction of International Financial Reporting
Standards (IFRSs) contributed to lower NIM variations unexplained by standard accounting
variables. Interest rate volatility is found to be positively and strongly related to
NIM dynamics, whereas inflation risk is often found to be a relevant driver of NIM crosscountry
differences
BioβBased Polyurethanes from Carbohydrate Monomers
The production of sustainable and environmentally friendly materials constitutes a growing field of attention. The incorporation of sugarβderived units into traditional stepβgrowth polymers such as polyamides, polyesters, and polyurethanes is a healthy method to prepare novel biodegradable and biocompatible materials for application in the biomedical field and other sectors such as foodstuff packaging
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