Related papers: Cosmological constant in broken maximal sugras
Combining general relativity and gravitational gauge theory, the cosmological constant is determined theoretically. The cosmological constant is related to the average vacuum energy of gravitational gauge field. Because the vacuum energy of…
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…
I review three attempts to explain the small value of the cosmological constant, and their connection to SUSY breaking. They are The String Landscape, Supersymmetric Large Extra Dimensions (SLED), and the Holographic Space-time Formalism…
We find a new class of cosmic string solutions with non-vanishing magnetic flux of $\mathcal{N}=1$, D=4 supergravity with a cosmological constant and coupled to any number of Maxwell and scalar multiplets. We show that these magnetic cosmic…
We give a basic review of some recent developments in local supersymmetry breaking in 4-dimensional effective theories coming from compactifications of string and M-theory in the presence of non-trivial form and geometrical fluxes.
In supersymmetric theories, topological defects can have nontrivial behaviors determined purely by whether or not supersymmetry is restored in the defect core. A well-known example of this is that some supersymmetric cosmic strings are…
In this thesis the cosmological constant is investigated from two points of view. First, we study the influence of a time-dependent cosmological constant on the late-time expansion of the universe. Thereby, we consider several combinations…
We describe the breaking of supersymmetry in M-theory by coordinate dependent (Scherk-Schwarz) compactification of the eleventh dimension. Supersymmetry is spontaneously broken in the gravitational and moduli sector and communicated to the…
We study the expansion of the universe at late times in the case that the cosmological constant obeys certain scaling laws motivated by renormalisation group running in quantum theories. The renormalisation scale is identified with the…
Using the flux compactification scenario in a generic supergravity model we construct a set of conditions which are necessary to generate de-Sitter or anti de-Sitter vacua for appropriate choices of the parameters in superpotential. It is…
Supersymmetry plays a main role in all current thinking about superstring theory. Indeed, many remarkable properties of string theory have been explained using supersymmetry as a tool. So far, there has been no unbroken supersymmetry…
Running of gauge couplings in the MSSM from a unified value at high energies leads to a successful prediction of the weak mixing angle. Supersymmetric models at the TeV scale may contain further hints of high scale physics, such as the…
We explore the possibility of a consistent cosmology based on the gauge-fixing independent running of the gravitational and cosmological constants ($G$ and $\Lambda$) in the framework of effective quantum gravity. In particular, their…
A generic form of low-energy effective action of superstring theories with one-loop quantum correction is well known. Based on this action we derive the complete perturbation equations and general analytic solutions in the cosmological…
We present a nonsupersymmetric orbifold of type II string theory and show that it has vanishing cosmological constant at the one and two loop level. We argue heuristically that the cancellation persists at higher loops.
In this talk we argue that the breakdown of global symmetries in no--scale supergravity (SUGRA), which ensures the vanishing of the vacuum energy density near the physical vacuum, leads to a natural realisation of the multiple point…
In 2 + 1 dimensions, in the presence of gravity, supersymmetry can ensure the vanishing of the cosmological constant without requiring the equality of bose and fermi masses.
In this paper, we analyse the effect of the expansion of the universe on the clustering of galaxies. We evaluate the configurational integral for interacting system of galaxies in an expanding universe by including effects produced by the…
A short review about vacuum energy and the cosmological constant is presented. The observed acceleration of the universe introduces a new meV energy scale. The problem is that, theoretically, the predicted vacuum energy is many orders of…
The cosmological constant problem is studied in a two component cosmological model. The universe contains a cosmological constant of an arbitrary size and sign and an additional component with an inhomogeneous equation of state. It is shown…