Naked Singularities in Four-Dimensional String Backgrounds

Abstract

It is shown that gauged nonlinear sigma models can be always deformed by terms proportional to the field strength of the gauge fields (nonminimal gauging). These deformations can be interpreted as perturbations, by marginal operators, of conformal coset models. When applied to the SL(2,R)*SU(2)/[U(1)*U(1)] WZWN model, a large class of four-dimensional curved spacetime backgrounds are obtained. In particular, a naked singularity may form at a time when the volume of the universe is different from zero.

15 pages, Latex file, BONN-HE-93-11

References in corpus (32)

• Duality, Quotients, and Currents
• Elements of String Cosmology
• $O(d,d)$-Covariant String Cosmology
• Generalized Duality in Curved String-Backgrounds
• A Closed, Expanding Universe in String Theory
• Conformally Exact Metric and Dilaton in String Theory on Curved Spacetime
• An Equivalence Between Momentum and Charge in String Theory
• Marginal Deformations of WZNW and Coset Models from O(d,d) Transformation
• Strings on Curved Spacetimes: Black Holes, Torsion, and Duality
• Cosmological String Backgrounds from Gauged WZW Models
• Boosting Away Singularities from Conformal String Backgrounds
• A Superstring Theory in Four Curved Space-Time Dimensions
• Some Exact Solutions of String Theory in Four and Five Dimensions
• Conformally Exact Results for SL(2,R)\times SO(1,1)^{d-2}/SO(1,1) Coset Models
• Exact Effective Action and Spacetime Geometry in Gauged WZW Models
• On Cosmological String Backgrounds with Toroidal Isometries
• Black Holes from Non-Abelian Toda Theories
• Duality, Marginal Perturbations and Gauging
• Exact Bosonic and Supersymmetric String Black Hole Solutions
• $SL(2,R)xSU(2)/R^2$ string model in curved spacetime and exact conformal results
• String Theory, Black Holes, and SL(2,R) Current Algebra
• Higher Order Conformal Invariance of String Backgrounds Obtained by O(d,d) Transformations
• Gauged String Actions and O($\tilde{d}$, $\tilde{d}$) Transformation
• $W_{\infty} Algebra in Two-Dimensional Black Hole
• Perturbations of a Stringy Black Hole
• World-Sheet Duality, Space-Time Foam, and the Quantum Fate of a Stringy Black Hole
• Four Dimensional Stringy Black Membrane
• Equivalence of BRST cohomologies for 2-d black hole and c=1 Liouville theory
• Four Dimensional 2-Brane Solution in Chiral Gauged Wess-Zumino-Witten Model
• Arbitrary Spacetimes from the SL(2,R)/U(1) Coset Model
• Modified Black Holes in Two Dimensional Gravity
• Non-Critical Strings in Robertson-Walker Space Time

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