Related papers: String Theory, Black Holes, and SL(2,R) Current Al…
String theory on AdS$_3$ with NS-NS fluxes admits a solvable irrelevant deformation which is close to the $T\bar{T}$ deformation of the dual CFT$_2$. This consists of deforming the worldsheet action, namely the action of the…
We use localization to evaluate the functional integral of string field theory on AdS_2xS^2 background corresponding to the near horizon geometry of supersymmetric black holes in 4d compactifications with N=2 supersymmetry. In particular,…
The study of black holes in string theory has led to the discovery of deep and surprising connections between black holes and modular forms -- which are two classical, a priori unrelated, subjects. This article explains the main physical…
The exact black hole solution of 2D closed string theory has, as any other maximally extended Schwarzschild-like geometry, two asymptotically flat spacetime domains. One can get rid of the second domain by gauging the discrete symmetry on…
We find the discrete states of the c=1 string in the light-cone gauge of Polyakov. When the state space of the gravitational sector of the theory is taken to be the irreducible representations of the SL(2,R) current algebra, the cohomology…
This thesis is almost entirely devoted to studying string theory backgrounds characterized by simple geometrical and integrability properties. The archetype of this type of system is given by Wess-Zumino-Witten models, describing string…
Massless fields propagating in a generic Kerr black hole background enjoy a hidden SL(2,R)xSL(2,R) symmetry. We determine how the exact mode functions decompose into representations of this symmetry group. This extends earlier results on…
We find double-extreme black holes associated with the special geometry of the Calabi-Yau moduli space with the prepotential F=STU. The area formula is STU-moduli independent and has ${[SL(2,Z)]}^3$ symmetry in space of charges. The dual…
We discuss aspects of the possible transition between small black holes and highly excited fundamental strings. We focus on the connection between black holes and the self gravitating string solution of Horowitz and Polchinski. This…
The leading classical low-energy effective actions for two-dimensional string theories have solutions describing the gravitational collapse of shells of matter into a black hole. It is shown that string loop corrections can be made…
The algebraic structure of S-Theory and its representations are described. This structure includes up to 13 hidden dimensions. It implies the existence of an SO(10,2) covariant supergravity theory as a limit of the secret theory behind…
We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O(3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used…
In the first part of this talk, I consider some exact string solutions in curved spacetimes. In curved spacetimes with a Killing vector (timelike or spacelike), the string equations of motion and constraints are reduced to the Hamilton…
We discuss the low-energy effective string theory when moduli of the compactified manifold are present. Assuming a nontrivial coupling of the moduli to the Maxwell tensor, we find a class of regular black hole solutions. Both the…
We study the ground states and left-excited states of the A_{k-1} N=(2,0) little string theory. Via a theorem by Atiyah [1], these sectors can be captured by a supersymmetric nonlinear sigma model on CP^1 with target space the based loop…
The refrerences are corrected.
Thin enough black strings are unstable to growing ripples along their length, eventually pinching and forming a naked singularity on the horizon. We investigate how string theory can resolve this singularity. First, we study the…
We consider non-compact WZW models at critical level (equal to the dual Coxeter number) as tensionless limits of gravitational backgrounds in string theory. Special emphasis is placed on the Euclidean black hole coset SL(2,R)_k/U(1) when…
New exact solutions of Einstein equations which describe black hole with radial cosmic strings are constructed in the paper. The case of infinitely thin strings and the case of delocalized strings are considered. The case of delocalized…
It is well known that non-perturbative $\alpha'$ corrections to the $SL(2,\IR)/U(1)$ cigar geometry are described via a condensation of a Sine-Liouville operator that schematically can be written as $W^{+}+W^{-}$, where $W^{\pm}$ describe a…