223 research outputs found

### (Super-) String in Two Dimensional Black Hole and Target Space Dualities

We review the recently proposed string theory in two dimensional black hole
background. Especially, the structure of the duality in the target space is
discussed. The duality is analogous to \lq\lq $R \rightarrow 1/R$" symmetry of
a compactified boson. We consider the duality in more general target space
manifolds which have Killing symmetries and we give an explicit formula which
connects two different manifolds which are dual to each other. Superstring
theory in two dimensional black hole background is also discussed based on
supersymmetric $SU(1,1)/U(1)$ gauged Wess-Zumino-Witten model.Comment: 19pp (Talk at YITP workshop, ``Developments in Strings and Field
Theories'', Kyoto, JAPAN

### Group Theoretical Structure of $N=1$ and $N=2$ Two-Form Supegravity

We clarifies the group theoretical structure of $N=1$ and $N=2$ two-form
supergravity, which is classically equivalent to the Einstein supergravity.
$N=1$ and $N=2$ two-form supergravity theories can be formulated as gauge
theories. By introducing two Grassmann variables $\theta^A$ ($A=1,2$), we
construct the explicit representations of the generators $Q^i$ of the gauge
group, which makes to express any product of the generators as a linear
combination of the generators $Q^iQ^j=\sum_k f^{ij}_k Q^k$. By using the
expression and the tensor product representation, we explain how to construct
finite-dimensional representations of the gauge groups. Based on these
representations, we construct the Lagrangeans of $N=1$ and $N=2$ two-form
supergravity theories.Comment: Latex file, 15

### Exact Four Dimensional Exploding Universe Solution in String Theory

We obtain a four dimensional exploding universe solution in string theory.
The solution is obtained from the string theory in the flat background by using
non-abelian $T$-duality and the analytic continuation. In the solution, the
radius of the universe is finite for fixed time and the universe is surrounded
with the boundary which is composed of the singularity. The boundary runs away
with the speed of light and the flat space-time is left behind.Comment: Latex file, 6 pages, misprints in Eqs.(14), (16), (19) and (26) are
correcte

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