Tax Smoothing with Stochastic Interest Rates: A Re-assessment of Clinton's Fiscal Legacy

The return to sound fiscal policy after the high budget deficits of the 1980s and early 1990s has been hailed by many as the Clinton administration's most important achievement. In this article, we evaluate post-war, US fiscal policy using an extension of Barro's (1979) tax-smoothing model, generalized to allow for stochastic variation in interest rates and growth rates. We show that the evolution of the US debt-GDP ratio has been remarkably consistent with the tax-smoothing paradigm, even during the 1980s. The only major departure occurred during the late 1990s, when the debt-GDP ratio fell more rapidly than predicted by optimal tax smoothing. Le retour vers une politique fiscale raisonnable après les déficits budgétaires élevés des années 1980 et du début des années 1990 a été acclamé par beaucoup comme la réalisation la plus importante de l'administration Clinton. Dans cet article, nous évaluons la politique fiscale des États-Unis d'après-guerre en utilisant une extension du modèle de lissage des impôts de Barro (1979), modèle généralisé pour permettre des variations stochastiques des taux d'intérêt et des taux de croissance. Nous montrons que l'évolution de ratio dette/PIB américain a été remarquablement conséquent avec le paradigme de lissage des impôts, même durant les années 1980. Le seul écart important a eu lieu durant la fin des années 1990, lorsque le ratio dette/PIB est tombé plus rapidement que ce qu'aurait prédit un lissage optimal des impôts.public debt, tax smoothing, stochastic discouting

Constraining Right-Handed Scale Through Kaon Mixing in SUSY Left-Right Model

We study flavor-changing neutral current and CP violations in the minimal supersymmetric left-right model. We calculate the beyond-standard-model contributions to the neutral kaon mixing $\Delta M_K$ and $\epsilon$, and find possible to have a numerical cancelation between the contributions from the right-handed gauge boson and supersymmetric box diagram. With the cancelation, the right-handed $W$-boson mass scale can be lowered to about 2 TeV, well within the search limit of LHC.Comment: 12 pages, new figures adde

Extending the Universal One-Loop Effective Action: Heavy-Light Coefficients

The Universal One-Loop Effective Action (UOLEA) is a general expression for the effective action obtained by evaluating in a model-independent way the one-loop expansion of a functional path integral. It can be used to match UV theories to their low-energy EFTs more efficiently by avoiding redundant steps in the application of functional methods, simplifying the process of obtaining Wilson coefficients of operators up to dimension six. In addition to loops involving only heavy fields, matching may require the inclusion of loops containing both heavy and light particles. Here we use the recently-developed covariant diagram technique to extend the UOLEA to include heavy-light terms which retain the same universal structure as the previously-derived heavy-only terms. As an example of its application, we integrate out a heavy singlet scalar with a linear coupling to a light doublet Higgs. The extension presented here is a first step towards completing the UOLEA to incorporate all possible structures encountered in a covariant derivative expansion of the one-loop path integral.Comment: 20 pages, 1 figure, 5 tables, 1 Mathematica Noteboo

Mixed Heavy-Light Matching in the Universal One-Loop Effective Action

Recently, a general result for evaluating the path integral at one loop was obtained in the form of the Universal One-Loop Effective Action. It may be used to derive effective field theory operators of dimensions up to six, by evaluating the traces of matrices in this expression, with the mass-dependence encapsulated in the universal coefficients. Here we show that it can account for loops of mixed heavy-light particles in the matching procedure. Our prescription for computing these mixed contributions to the Wilson coefficients is conceptually simple. Moreover it has the advantage of maintaining the universal structure of the effective action, which we illustrate using the example of integrating out a heavy electroweak triplet scalar coupling to a light Higgs doublet. Finally we also identify new structures that were previously neglected in the universal results.Comment: 22 pages, 3 figures; v2: expanded discussion in Section 3, typos correcte

Dynamics of Quantum Dot Photonic Crystal Lasers

Quantum dot photonic crystal membrane lasers were fabricated and the large signal modulation characteristics were studied. We find that the modulation characteristics of quantum dot lasers can be significantly improved using cavities with large spontaneous emission coupling factor. Our experiments show, and simulations confirm, that the modulation rate is limited by the rate of carrier capture into the dots to around 30GHz in our present system

Calculations of Neutralino-Stau Coannihilation Channels and the Cosmologically Relevant Region of MSSM Parameter Space

Assuming that the lightest supersymmetric particle (LSP) is the lightest neutralino, we present a detailed exploration of neutralino-stau coannihilation channels, including analytical expressions and numerical results. We also include neutralino coannihilations with the selectron and smuon. We evaluate the implications of coannihilations for the cosmological relic density of the LSP, which is assumed to be stable, in the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the soft supersymmetry-breaking parameters are universal at the supergravity GUT scale. We evaluate the changes due to coannihilations in the region of the MSSM parameter space that is consistent with the cosmological upper limit on the relic LSP density. In particular, we find that the upper limit on the mass of the neutralino is increased from about 200 GeV to about 600 GeV in the CMSSM, and estimate a qualitatively similar increase for gauginos in the general MSSM.Comment: 38 pages in LaTeX, including 25 encapsulated postscript figures. Added small clarification in the text, corrected some typos in the appendix. Figures and conclusions unchange

Equilibrium securitization with diverse beliefs

We study the effects of diverse beliefs on equilibrium securitization under risk neutrality. We provide a simple characterization of the optimal securities. Pooling and tranching of assets emerges in equilibrium as a consequence of the traders' diverse beliefs about asset returns. The issuer of securities tranches the asset pool, and traders sort among the tranches according to their beliefs. We show how the traders' disagreement about the correlation of asset returns is a key factor in determining which assets are pooled

Principle of Balance and the Sea Content of the Proton

In this study, the proton is taken as an ensemble of quark-gluon Fock states. Using the principle of balance that every Fock state should be balanced with all of the nearby Fock states (denoted as the balance model), instead of the principle of detailed balance that any two nearby Fock states should be balanced with each other (denoted as the detailed balance model), the probabilities of finding every Fock state of the proton are obtained. The balance model can be taken as a revised version of the detailed balance model, which can give an excellent description of the light flavor sea asymmetry (i.e., $\bar{u}\not= \bar{d}$) without any parameter. In case of $g\Leftrightarrow gg$ sub-processes not considered, the balance model and the detailed balance model give the same results. In case of $g\Leftrightarrow gg$ sub-processes considered, there is about 10 percent difference between the results of these models. We also calculate the strange content of the proton using the balance model under the equal probability assumption.Comment: 32 latex pages, 4 ps figures, to appear in PR