Is String Theory a Theory of Quantum Gravity?

Topics in String Theory and Quantum Gravity

2D String Theory Coupled to Quantum Gravity

We consider self-avoiding Nambu-Goto open strings on a random surface. We have shown that the partition function of such a string theory can be calculated exactly. The string susceptibility for the disk is evaluated to be − 2 . We also consider modifications of the Nambu-Goto action which are exactly soluble on a random surface.

Locality in quantum gravity and string theory

Breakdown of local physics in string theory at distances longer than the string scale is investigated. Such nonlocality would be expected to be visible in ultrahigh-energy scattering. The results of various approaches to such scattering are collected and examined. No evidence is found for nonlocality from strings whose length grows linearly with the energy. However, local quantum field theory d...

AdS2 Quantum Gravity and String Theory

AdS2 has an SL(2, R) isometry group. It is argued that in the context of quantum gravity on AdS2 this group is enlarged to the full infinite-dimensional 1+1 conformal group. Massive scalar fields are coupled to AdS2 gravity and shown to have associated conformal weights h(m) shifted by their mass. For integral values of h primary boundary operators are obtained as h normal derivatives of the sc...

String Theory and Gravity*

It is pointed out that string-loop effects may generate matter couplings for the dilaton allowing this scalar partner of the tensorial graviton to stay massless while contributing to macroscopic gravity in a way naturally compatible with existing experimental data. Under a certain assumption of universality of the dilaton coupling functions (possibly realized through a discrete symmetry such as...