2,211 research outputs found
F^4 Terms in N=4 String Vacua
We discuss terms in torroidal compactifications of type-I and
heterotic SO(32) string theory. We give a simple argument why only short BPS
multiplets contribute to these terms at one loop, and verify heterotic-type-I
duality to this order.Comment: 10 pages, Latex. A statement about superinvariants was corrected.
Minor cosmetic changes were also made. To appear in Proceedings of Trieste
Spring School and Workshop, April 199
An Initial Value Problem for Oscillations of the Interstellar Gas
Initial value problem for oscillations in interstellar ga
On the classification of (2,1) heterotic strings
We classify all untwisted (2,1) heterotic strings. The only solutions are the
three already known cases, having massless spectra consisting either of 24
chiral fermions, or of 24 bosons, or of 8 scalars and 8 fermions of each
chirality.Comment: Phyzzx and Tables macro packages require
On Heterotic/Type I Duality in d=8
We discuss heterotic corrections to quartic internal U(1) gauge couplings and
check duality by calculating one-loop open string diagrams and identifying the
D-instanton sum in the dual type I picture. We also compute SO(8)^4 threshold
corrections and finally R^2 corrections in type I theory.Comment: 9 pages, Latex, To appear in the proceedings of "Quantum Aspects of
Gauge Theories, Supersymmetries and Unification", Corfu, September 199
Chiral Rings, Vacua and Gaugino Condensation of Supersymmetric Gauge Theories
We find the complete chiral ring relations of the supersymmetric U(N) gauge
theories with matter in adjoint representation. We demonstrate exact
correspondence between the solutions of the chiral ring and the supersymmetric
vacua of the gauge theory. The chiral ring determines the expectation values of
chiral operators and the low energy gauge group. All the vacua have nonzero
gaugino condensation. We study the chiral ring relations obeyed by the gaugino
condensate. These relations are generalizations of the formula
of the pure gauge theory.Comment: 38 page
Free-field Representations and Geometry of some Gepner models
The geometry of Gepner model, where is investigated by
free-field representation known as "bc\bet\gm"-system. Using this
representation it is shown directly that internal sector of the model is given
by Landau-Ginzburg -orbifold. Then we consider
the deformation of the orbifold by marginal anti-chiral-chiral operator.
Analyzing the holomorphic sector of the deformed space of states we show that
it has chiral de Rham complex structure of some toric manifold, where toric
dates are given by certain fermionic screening currents. It allows to relate
the Gepner model deformed by the marginal operator to the -model on CY
manifold realized as double cover of with ramification along
certain submanifold.Comment: LaTex, 14 pages, some acknowledgments adde
Generalized Calabi-Yau Manifolds and the Mirror of a Rigid Manifold
We describe the mirror of the Z orbifold as a representation of a class of
generalized Calabi-Yau manifolds that can be realized as manifolds of dimension
five and seven. Despite their dimension these correspond to superconformal
theories with and so are perfectly good for compactifying the heterotic
string to the four dimensions of space-time. As a check of mirror symmetry we
compute the structure of the space of complex structures of the mirror and
check that this reproduces the known results for the Yukawa couplings and
metric appropriate to the Kahler class parameters on the Z orbifold together
with their instanton corrections.Comment: 39 pages, plain Te
Estimating the size of the cosmic-ray halo using particle distribution moments
Context: Particle transport in many astrophysical problems can be described either by the Fokker–Planck equation or by an equivalent system of stochastic differential equations. Aims: It is shown that the latter method can be applied to the problem of defining the size of the cosmic-ray galactic halo. Methods: Analytical expressions for the leading moments of the pitch-angle distribution of relativistic particles are determined. Particle scattering and escape are analyzed in terms of the moments. Results: In the case of an anisotropic distribution, the first moment leads to an expression for the halo size, identified with the particle escape from the region of strong scattering. Previous studies are generalized by analyzing the case of a strictly isotropic initial distribution. A new expression for the variance of the distribution is derived, which illustrates the anisotropization of the distribution. Conclusions: Stochastic calculus tools allow one to analyze physically motivated forms for the scattering rate, so that a detailed realistic model can be developed
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