Related papers: Recent Developments in Fractional Superstrings
We construct new superstring actions which are distinguished from standard superstrings by being space-time scale invariant. Like standard superstrings, they are also reparametrization invariant, space-time supersymmetric, and invariant…
In this lecture I summarize recent developments on strings propagating in curved spacetime. Exact conformal field theories that describe gravitational backgrounds such as black holes and more intricate gravitational singularities have been…
In these lectures, I review the current status of cosmic strings and cosmic superstrings. I first discuss topological defects in the context of Grand Unified Theories, focusing in particular in cosmic strings arising as gauge theory…
The phenomenological aspects of string theory are briefly reviewed. Emphasis is given to the status of 4D string model building, effective Lagrangians, model independent results, supersymmetry breaking and duality symmetries.
New Developments in String Gravity and String Cosmology are reported: 1-String driven cosmology and its Predictions. 2-The primordial gravitational wave background in string cosmology. 3-Non-singular string cosmologies from Exact Conformal…
Open and Closed super-string field theories are constructed in an event-symmetric target space. The partition functions of Statistical and Quantum models are constructed in terms of invariants defined on Lie-algebra representations. An…
Superstring theories are very promising theoretically, but the enormous landscape of string vacua and the (likely) very large underlying string scale imply that they may never be tested directly. Nevertheless, concrete constructions…
Recent developments in superstring phenomenology are summarized on a non-technical level. (Talk presented at the XXVIIth Rencontre de Moriond on Electroweak Interactions and Unified Theories.)
A new type of sectional curvature is introduced. The notion is purely algebraic and can be located in linear algebra as well as in differential geometry.
A new type of tensionless superstring theory, called the Inhomogeneous tensionless superstring, has been recently introduced. This is characterised by a residual symmetry algebra on the worldsheet richer in structure than the previously…
Four-dimensional string theories predict in general the existence of light exotic particles with fractional electric charges. Such particles could escape present observations if they are confined by a gauge group of the "hidden" sector into…
The present status of superstring phenomenology is briefly discussed.
We propose that a novel deformation of string perturbation theory, involving non-local interactions between strings, is required to describe the gravity duals of field theories deformed by multiple-trace operators. The new perturbative…
Three subjects are considered here: a self-dual non-critical string that appears in Type IIB superstring theory at points in ${\rm K3}$ moduli space where the Type IIA theory has extended gauge symmetry; a conformal field theory singularity…
We explain how fractional spin and statistics are relevant to (super)strings in a three-dimensional (3D) Minkowski spacetime.
The divergences that arise in the regularized partition function for closed bosonic string theory in flat space lead to three types of perturbation series expansions, distinguished by their genus dependence. This classification of…
String theory is canonically accompanied with a space-time interpretation which determines S-matrix-like observables, and connects to the standard physics at low energies in the guise of local effective field theory. Recently, we have…
Recently, a new framework for solving the hierarchy problem has been proposed which does not rely on low energy supersymmetry or technicolor. The gravitational and gauge interactions unite at the electroweak scale, and the observed weakness…
Perturbative superstring theory is revisited, with the goal of giving a simpler and more direct demonstration that multi-loop amplitudes are gauge-invariant (apart from known anomalies), satisfy space-time supersymmetry when expected, and…
Some of the properties of string theory defined on world-sheets with boundaries are reviewed. Particular emphasis is put on the possibility of identifying string configurations (\lq D-instantons' and \lq D-branes') that give rise to stringy…