12,529 research outputs found

### Quantum Electrodynamics at Large Distances III: Verification of Pole Factorization and the Correspondence Principle

In two companion papers it was shown how to separate out from a scattering
function in quantum electrodynamics a distinguished part that meets the
correspondence-principle and pole-factorization requirements. The integrals
that define the terms of the remainder are here shown to have singularities on
the pertinent Landau singularity surface that are weaker than those of the
distinguished part. These remainder terms therefore vanish, relative to the
distinguished term, in the appropriate macroscopic limits. This shows, in each
order of the perturbative expansion, that quantum electrodynamics does indeed
satisfy the pole-factorization and correspondence-principle requirements in the
case treated here. It also demonstrates the efficacy of the computational
techniques developed here to calculate the consequences of the principles of
quantum electrodynamics in the macroscopic and mesoscopic regimes.Comment: latex, 39 pages, 2 Figures included as uuencoded, tarred, gzipped,
encapsulated postscript files, uses math_macros.te

### T-duality of ZZ-brane

We examine how nonperturbative effects in string theory are transformed under
the T-duality in its nonperturbative framework by analyzing the c=1/2
noncritical string theory as a simplest example. We show that in the T-dual
theory they also take the form of exp(-S_0/g_s) in the leading order and that
the instanton actions S_0 of the dual ZZ-branes are exactly the same as those
in the original c=1/2 string theory. Furthermore we present formulas for
coefficients of exp(-S_0/g_s) in the dual theory.Comment: 37 pages, no figure, LaTeX; (v2) version published in Physical Review

### Asymmetric Non-Abelian Orbifolds and Model Building

The rules for the free fermionic string model construction are extended to
include general non-abelian orbifold constructions that go beyond the real
fermionic approach. This generalization is also applied to the asymmetric
orbifold rules recently introduced. These non-abelian orbifold rules are quite
easy to use. Examples are given to illustrate their applications.Comment: 30 pages, Revtex 3.

### Scaling Behavior of Ricci Curvature at Short Distance near Two Dimensions

We study the renormalization of the Ricci curvature as an example of
generally covariant operators in quantum gravity near two dimensions. We find
that it scales with a definite scaling dimension at short distance. The Ricci
curvature singularity at the big bang can be viewed as such a scaling
phenomenon. The problem of the spacetime singularity may be resolved by the
scale invariance of the spacetime at short distance.Comment: 9pages, LaTe

### Quantum Electrodynamics at Large Distances II: Nature of the Dominant Singularities

Accurate calculations of macroscopic and mesoscopic properties in quantum
electrodynamics require careful treatment of infrared divergences: standard
treatments introduce spurious large-distances effects. A method for computing
these properties was developed in a companion paper. That method depends upon a
result obtained here about the nature of the singularities that produce the
dominant large-distance behaviour. If all particles in a quantum field theory
have non-zero mass then the Landau-Nakanishi diagrams give strong conditions on
the singularities of the scattering functions. These conditions are severely
weakened in quantum electrodynamics by effects of points where photon momenta
vanish. A new kind of Landau-Nakanishi diagram is developed here. It is geared
specifically to the pole-decomposition functions that dominate the macroscopic
behaviour in quantum electrodynamics, and leads to strong results for these
functions at points where photon momenta vanish.Comment: 40 pages, 11 encapsulated postscript figures, latexed,
math_macros.tex can be found on Archive. full postscript available from
http://theorl.lbl.gov/www/theorgroup/papers/35972.p

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