Gravitational Properties of Quantum Bosonic Strings
Abstract
In this thesis we are interested in the study of the gravitational properties of quantum bosonic strings. We start by computing the quantum energymomentum tensor ${\hat T}^{\mu\nu}(x)$ for strings in Minkowski spacetime. We perform the calculation of its expectation value for different physical string states both for open and closed bosonic strings. The states we consider are described by normalizable wavepackets in the centre of mass coordinates. Amongst our results, we find in particular that ${\hat T}^{\mu\nu}(x)$ becomes a nonlocal operator at the quantum level, its position appears to be smeared out by quantum fluctuations. We find that the expectation value acquires a nonzero value for both massive and massless string states. After computing $<{\hat T}^{\mu\nu}(x)>$ we proceed to calculate the gravitational field due to a quantum massless bosonic string in the framework of a weakfield approximation to Einstein's equations. We obtain a multipole expansion for the weakfield metric $h^{\mu\nu}(x)$ and present its gravitational properties, including the gravitational radiation produced by such a string. Our results are then compared to those found for classical (cosmic) strings.
 Publication:

arXiv eprints
 Pub Date:
 July 1997
 DOI:
 10.48550/arXiv.grqc/9707061
 arXiv:
 arXiv:grqc/9707061
 Bibcode:
 1997gr.qc.....7061V
 Keywords:

 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 Ph.D Thesis. 143 pages, 25 figures inluded. Primary Latex file: Thesisroot.tex (56 subsidiary files).