287 research outputs found
Clock and Category; IS QUANTUM GRAVITY ALGEBRAIC
We investigate the possibility that the quantum theory of gravity could be
constructed discretely using algebraic methods. The algebraic tools are similar
to ones used in constructing topological quantum field theories.The algebraic
tools are related to ideas about the reinterpretation of quantum mechanics in a
general relativistic context.Comment: To appear in special issue of JMP. Latex documen
Wilson Loops and Black Holes in 2+1 Dimensions
In 2+1 dimensional Chern-Simons gravity, Wilson loops in the three
dimensional Anti de Sitter group, , reproduce the spinning black hole
of Ba\~nados, Teitelboim and Zanelli (BTZ) by naturally duplicating the
necessary identification of points of a four dimensional globally
invariant space in which the hole appears as an embedding.Comment: PHYZZX, 10 pages, UATP-930
Type IIB orientifolds with discrete torsion
We consider compact four-dimensional type IIB
orientifolds, for certain values of and . We allow the additional
feature of discrete torsion and discuss the modification of the consistency
conditions arising from tadpole cancellation. We point out the differences
between the cases with and without discrete torsion.Comment: 4 pages LaTeX. Write-up of talk at DPF2000, Columbus, OH, August 10,
2000. References adde
Quantum Symmetries and Stringy Instantons
The quantum symmetry of many \LG\ orbifolds appears to be broken by
Yang-Mills instantons. However, isolated Yang-Mills instantons are not
solutions of string theory: They must be accompanied by gauge anti-instantons,
gravitational instantons, or topologically non-trivial configurations of the
field. We check that the configurations permitted in string theory do in
fact preserve the quantum symmetry, as a result of non-trivial cancellations
between symmetry breaking effects due to the various types of instantons. These
cancellations indicate new constraints on \LG\ orbifold spectra and require
that the dilaton modulus mix with the twisted moduli in some \LG\
compactifications. We point out that one can find similar constraints at all
fixed points of the modular group of the moduli space of vacua.Comment: 14pp, harvmac, PUPT--146
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