Student Theses and Dissertations

Date of Award

1988

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Thesis Advisor

Louise Dolan

Keywords

string theory, spacetime dimensions, critical dimensions, superstrings, bosonic string, supersymmetry, compactification, heterotic strings

Abstract

All of the work presented in this thesis evolved from the initial idea that strings, if they are to make sense, ought to exist in four spacetime dimensions. At the time that it was formulated, back in mid-1985, such an idea was thought to be impossible. There were only five string theories that were known to be fully consistent, and each of these had a critical dimension of 10. The bosonic (or Veneziano) string has to live in 26 spacetime dimensions, or else a breakdown of Lorentz invariance occurs. But it is not a fully consistent theory because it contains a tachyon (a particle with negative mass squared) in its spectrum and its amplitudes have infinities. The open (type I) as well as the closed (type II) superstrings introduce supersymmetry into the theory, and this reduces the critical dimension from 26 down to 10. The type I superstring is N=1 supersymmetric, whereas the type II string is N=2. The E8 x E8 and Spin(32)/Z2 heterotic strings are hybrids (or heteroses) of the 10-dimensional superstring and compactified versions of the 26-dimensional bosonic string, and they too have ten as their critical number of dimensions. All of these theories have very appealing features in their critical number of dimensions, and the hope was to maintain as many of these features as possible while reducing the spacetime dimension down to what we know it must be on the everyday scale of events - namely four.

Comments

A thesis presented to the faculty of The Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy

License and Reuse Information

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.

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