Related papers: Non-Supersymmetric String Theory
Regarding the current status of the superstring theory, despite its fully developed contents of all interactions in nature, it is no doubt that unfortunately it lacks a well established early universe cosmology content, that is, the…
We improve the study of the lack of perturbative unitarity of noncommutative space-time quantum field theories derived from open string theory in electric backgrounds, enforcing the universality of the mechanism by which a tachyonic branch…
In the Matrix Quantum Mechanical formulation of 2D string theory it is possible to introduce arbitrary tachyonic perturbations. In the case when the tachyonic momenta form a lattice, the theory is known to be integrable and, therefore, it…
Two new effects of interaction of the gauge string with a homogeneous density of fermions are considered in a gauge model with an anomalous coupling of vector fields with fermions. First, the presence of an induced nonzero magnetic-like…
We construct a Galilean invariant non-gravitational closed string theory whose excitations satisfy a non-relativistic dispersion relation. This theory can be obtained by taking a consistent low energy limit of any of the conventional string…
We discuss tachyon configuration for the unoriented bosonic string theory which produces a bosonic string theory with SO(32) gauge symmetry in ten dimensions. It is closely related to the tachyon condensation scenario proposed by A. Sen. We…
We revisit the non-linear sigma model approach to string theory with the closed superstring field theory. We construct the string field theory around the non-linear sigma model background with the patch-by-patch description. We show that…
String geometry theory is one of the candidates of the non-perturbative formulation of string theory. In this paper, from the string geometry theory, we derive path-integrals of perturbative superstrings on all the string backgrounds,…
Nonrelativistic string theory is a self-contained corner of string theory, with its string spectrum enjoying a Galilean-invariant dispersion relation. This theory is unitary and ultraviolet complete, and can be studied from first…
We present a class of solvable models that resemble string theories in many respects but have a strikingly different non-perturbative sector. In particular, there are no exponentially small contributions to perturbation theory in the string…
Brane inflation is a specific realization of the inflationary universe scenario in the early universe within the brane world framework in string theory. The naturalness and robustness of this realistic scenario is explained. Its predictions…
The noncommutative string theory is described by embedding open string theory in a constant second rank antisymmetric $B_{\mu\nu}$ field and the noncommutative gauge theory is defined by a deformed $\star$ product. As a check, study of…
This is a set of lectures on the gauge/string duality and non-critical strings, with a particular emphasis on the discretized, or matrix model, approach. After a general discussion of various points of view, I describe the recent…
Closed string tachyons have long been somewhat mysterious. We note that there is often a regime in the classical moduli space in which one can systematically compute the effective action for such fields. In this regime, the tachyon is…
One cannot yet point to any firm string prediction. While many approximate string ground states are known with interesting properties, we do not have any argument that one or another describes what we observe around us, and for reasons…
We observe a relation between closed strings tachyons and one-loop instabilities in non-supersymmetric non-commutative gauge theories. In particular we analyze the spectra of type IIB string theory on C^3/Z_N orbifold singularities and the…
Recent developments in inflation model building, based on supersymmetry, have produced compelling models in which strings are produced at the end of inflation. In such models the cosmological perturbations are seeded both by the defects and…
In this thesis we investigate the microphysics of cosmic strings in non-minimal quantum field theories. In particular we consider theories in which fermion fields couple to the strings, and those with larger symmetry groups, such as grand…
We study the possibility of extended inflation in the effective theory of gravity from strings compactified to four dimensions and find that it strongly depends on the mechanism of supersymmetry breaking. We consider a general class of…
We study closed string tachyon condensation using the RG flow of the worldsheet theory. In many cases the worldsheet theory enjoys N=2 supersymmetry, which provides analytic control over the flow, due to non-renormalization theorems.…