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UBC Theses and Dissertations
Tachyons, boundary interactions, and the genus expansion in string theory Laidlaw, Mark Colin Andrew
Abstract
This thesis examines the interaction of both bosonic- and superstrings with various backgrounds with a view to understanding the interplay between tachyon condensation and world-sheet conformal invariance, and to understanding the d-branes that overlap with closed string modes. We briefly review the development of both background independent string field theory and cubic string field theory, as these provide insight into the problem of tachyon condensation. We then develop the boundary state and show that in backgrounds of interest to tachyon condensation the conformal invariance of the string world-sheet is broken, which suggests a generalized boundary state obtained by integrating over the conformal group of the disk. We find that this prescription reproduces particle emission amplitudes calculated from the string sigma model for both on- and off-shell boundary interactions. The boundary state appears as a coherent superposition of closed string states, and using this a method for calculating amplitudes beyond tree level is developed. The interaction of closed strings with other backgrounds is also discussed. An extension of the boundary state to encode fields other than a gauge or tachyon field is described. A modification of the boundary state which encodes the time dependence of tachyon condensation is reviewed, and an examination of spherically symmetric tachyon condensation in the 1/D expansion is presented.
Item Metadata
Title |
Tachyons, boundary interactions, and the genus expansion in string theory
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2003
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Description |
This thesis examines the interaction of both bosonic- and superstrings with
various backgrounds with a view to understanding the interplay between
tachyon condensation and world-sheet conformal invariance, and to understanding
the d-branes that overlap with closed string modes. We briefly
review the development of both background independent string field theory
and cubic string field theory, as these provide insight into the problem of
tachyon condensation. We then develop the boundary state and show that in
backgrounds of interest to tachyon condensation the conformal invariance of
the string world-sheet is broken, which suggests a generalized boundary state
obtained by integrating over the conformal group of the disk. We find that
this prescription reproduces particle emission amplitudes calculated from the
string sigma model for both on- and off-shell boundary interactions. The
boundary state appears as a coherent superposition of closed string states,
and using this a method for calculating amplitudes beyond tree level is developed.
The interaction of closed strings with other backgrounds is also
discussed. An extension of the boundary state to encode fields other than
a gauge or tachyon field is described. A modification of the boundary state
which encodes the time dependence of tachyon condensation is reviewed, and
an examination of spherically symmetric tachyon condensation in the 1/D
expansion is presented.
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Extent |
5896426 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-11-13
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085725
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2003-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.