# String Theory

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# Contents

Introduction Supersymmetry Two-Dimensional Conformal Field Theory String Quantization The Free String String Interactions String Field Theory Compactification Orbifolds and Orientifolds T-Duality D-branes 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.