Trade and Development in Vietnam: Exploring Investment Linkages

This paper presents and uses a new, stylized single country dynamic CGE model to explore the trade-development linkages in Vietnam. Application of this framework involves addressing three basic questions: 1. Does a model that properly determines capacity additions and more fully captures macroeconomic accounting and growth dynamics predict trade levels in a satisfactory manner? 2. Are those capacity additions determined by trade liberalization, and if so, which aspects of trade liberalization? 3. Under this framework what are expected impacts of trade liberalization initiatives, such as past bilateral trade agreements and recent WTO accession, taking into account their potential effect on incentives to invest via both tariff changes and institutional reforms? We also explore the role of the state in determining investment patterns, since the government of Vietnam has played a crucial role in setting both the aggregate level and sectoral pattern of investment in the past. But recently there has been a recovery of foreign investment as well as an upsurge of investment by the domestic private sector. Moreover, Vietnam’s WTO accession agreement was as much about incentives to FDI as it was about tariff concessions, and it spurred ongoing institutional reforms that impact the investment climate.trade, development, Vietman, investment linkages

Can the Electroweak Symmetry-breaking Sector Be Hidden?

In a recent paper, Chivukula and Golden claimed that the electroweak symmetry--breaking sector could be hidden if there were many inelastic channels in the longitudinal $WW$ scattering process. They presented a model in which the $W$'s couple to pseudo--Goldstone bosons, which may be difficult to detect experimentally. Because of these inelastic channels, the $WW$ interactions do not become strong in the TeV region. We demonstrate that, despite the reduced $WW$ elastic amplitudes in this model, the total event rate ($\sim 5000$ extra longitudinal $W^+W^-$ pairs produced in one standard SSC year) does not decrease with an increasing number of inelastic channels, and is roughly the same as in a model with a broad high--energy resonance and no inelastic channels.Comment: 10 pages, phyzzx, JHU-TIPAC-92001

1+3 Covariant Cosmic Microwave Background anisotropies II: The almost - Friedmann Lemaitre model

This is the second of a series of papers extending the 1+3 covariant and gauge invariant treatment of kinetic theory to an examination of Cosmic Microwave Background temperature anisotropies arising from inhomogeneities in the early universe. The first paper dealt with algebraic issues. Here we derive the mode form of the integrated Boltzmann equations, first, giving a covariant version of the standard derivation using the mode recursion relations, second, demonstrating the link to the multipole divergence equations and finally various analytic ways of solving the resulting equations are discussed. A general integral form of solution is obtained for the equations with Thomson scattering. The covariant Friedmann-Lemaitre multipole form of the transport equations are found using the covariant and gauge-invariant generalization of the Peebles and Yu expansion in Thompson scattering time. The dispersion relations and damping scale are then obtained from the covariant approach. The equations are integrated to give the covariant and gauge-invariant equivalent of the canonical scalar sourced anisotropies. We carry out a simple treatment of the matter dominated free-streaming projection, slow decoupling, and tight-coupling cases, with the aim both giving a unified transparent derivation of this range of results and clarifying the connection between the more usual approaches (for example that of Hu and Sugiyama) and the treatment for scalar perturbations (for example the treatment of Challinor and Lasenby).Comment: To appear in Annals of Physic

Leading logarithmic QCD corrections to the B_s --> \gamma \gamma decays in the two Higgs doublet model

We calculate the leading logarithmic QCD corrections to the decay B_s --> \gamma \gamma in the two Higgs doublet model (2HDM) including O_7 type long distance effects and estimate the restrictions of the 2HDM parameters, tan\beta and m_H, using the experimental data of B --> X_s \gamma decay provided by the CLEO collaboration. A lower bound for the charged Higgs mass m_H as a function of the renormalization scale \mu is given for 2HDM model II. We further present the dependencies of the branching ratio Br(B_s --> \gamma \gamma) and the ratio |A^{+}|^2/|A^{-}|^2 on m_H and tan\beta including leading logarithmic QCD corrections. The dependence on the renormalization scale is found to be strong for both ratios. An additional uncertainty arises from the variation of the parameters of the bound state model, (m_b, \bar{\Lambda}_s). We see, that to look for charged Higgs effects the measurement of the branching ratio Br(B_s --> \gamma \gamma) is promising.Comment: 25 pages, 19 figures (required epsf.sty

Letter, 1975 January 19, from Nancy Abbot to Eva Jessye

1 page, this is a birhtday card

Navigating Around the Algebraic Jungle of QCD: Efficient Evaluation of Loop Helicity Amplitudes

A method is developed whereby spinor helicity techniques can be used to simplify the calculation of loop amplitudes. This is achieved by using the Feynman-parameter representation where the offending off-shell loop momenta do not appear. Background Feynman gauge also helps to simplify the calculations. This method is applicable to any Feynman diagram with any number of loops as long as the external masses can be ignored, and it is at least as efficient as the string technique in the special circumstances when the latter can be used. In order to minimize the very considerable algebra encountered in non-abelian gauge theories, graphical methods are developed for most of the calculations. This enables the large number of terms encountered to be organized visually in the Feynman diagram without the necessity of having to write down any of them algebraically. A one-loop four-gluon amplitude in a particular helicity configuration is computed explicity to illustrate the method.Comment: 22 pages of text in PLAIN TEX, plus 14 figures in 10 pages stored in a POSTSCRIPT file (attached to the end of the PLAIN TEX file); McGill preprint no. McGill/92-3

Freely falling 2-surfaces and the quasi-local energy

We derive an expression for effective gravitational mass for any closed spacelike 2-surface. This effective gravitational energy is defined directly through the geometrical quantity of the freely falling 2-surface and thus is well adapted to intuitive expectation that the gravitational mass should be determined by the motion of test body moving freely in gravitational field. We find that this effective gravitational mass has reasonable positive value for a small sphere in the non-vacuum space-times and can be negative for vacuum case. Further, this effective gravitational energy is compared with the quasi-local energy based on the $(2+2)$ formalism of the General Relativity. Although some gauge freedoms exist, analytic expressions of the quasi-local energy for vacuum cases are same as the effective gravitational mass. Especially, we see that the contribution from the cosmological constant is the same in general cases.Comment: 11 pages, no figures, REVTeX. Estimation of the effective mass of small spheres in non-vaccum spacetime and Schwarzschild spacetime are added. The negativity of the latter is discusse

Conserved charges for gravity with locally AdS asymptotics

A new formula for the conserved charges in 3+1 gravity for spacetimes with local AdS asymptotic geometry is proposed. It is shown that requiring the action to have an extremum for this class of asymptotia sets the boundary term that must be added to the Lagrangian as the Euler density with a fixed weight factor. The resulting action gives rise to the mass and angular momentum as Noether charges associated to the asymptotic Killing vectors without requiring specification of a reference background in order to have a convergent expression. A consequence of this definition is that any negative constant curvature spacetime has vanishing Noether charges. These results remain valid in the limit of vanishing cosmological constant.Comment: 5 pages, 2 Columns, revtex. Last version for Phys. Rev. Let

Fractional differentiability of nowhere differentiable functions and dimensions

Weierstrass's everywhere continuous but nowhere differentiable function is shown to be locally continuously fractionally differentiable everywhere for all orders below the `critical order' 2-s and not so for orders between 2-s and 1, where s, 1<s<2 is the box dimension of the graph of the function. This observation is consolidated in the general result showing a direct connection between local fractional differentiability and the box dimension/ local Holder exponent. Levy index for one dimensional Levy flights is shown to be the critical order of its characteristic function. Local fractional derivatives of multifractal signals (non-random functions) are shown to provide the local Holder exponent. It is argued that Local fractional derivatives provide a powerful tool to analyze pointwise behavior of irregular signals.Comment: minor changes, 19 pages, Late