String Theory

=Contents=
 * Introduction
 * Supersymmetry
 * Two-Dimensional Conformal Field Theory
 * String Quantization
 * The Free String
 * String Interactions
 * String Field Theory Compactifications
 * Orbifolds and Orientifolds
 * T-Duality
 * T-Duality
 * M-theory

=Notation= The metric has signature $$(+,-,-,-,...)$$.

Greek letters from the middle of the alphabet $$(\mu,\nu,...)$$ denote coordinates in spacetime. Roman letters taken from the beginning of the alphabet $$(a,b,...)$$ denote coordinates on the worldsheet.

The metric is denoted $$g_{\mu \nu}$$. In the case where there is a metric of spacetime and a metric of the worldsheet, the worldsheet metric is denoted $$h_{a b}$$

A lower-case $$d$$ is the number of dimensions. An upper-class $$D$$ represents the number of spacial dimensions.

=The Free String=

The Heterotic String Theories
=String Interactions=

=String Field Theory=

=Compactification=

=Orbifolds and Orientifolds=

=T-Duality=

=D-branes=

=M-Theory=