2003/09/04 by Mark Laidlaw, Laidlaw, M.
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · Computer Science · #Algorithms and Data Compression #Botanical Research and Chemistry #FOS: Physical sciences #Genome Rearrangement Algorithms #High Energy Physics - Theory (hep-th)
paper · pdf · doi:10.48550/arxiv.hep-th/0309055
openalex publication_date 2003/09/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 overlap of d-branes and closed string modes. We develop the boundary state and show that in a background 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 observation a proposal for calculating amplitudes beyond tree level is developed. The application of this technique to more general, time dependent backgrounds is also discussed.