Related papers: Chiral Heterotic Strings with Positive Cosmologica…
We study a cosmic string solution of an N=1-supersymmetric version of the Cremmer-Scherk-Kalb-Ramond (CSKR) Lagrangian coupled to a vector superfield by means of a topological mass term. The 2-form gauge potential is proposed to couple…
With no free parameter (except the string scale $M_S$), dynamical flux compactification in Type IIB string theory determines both the cosmological constant (vacuum energy density) $\Lambda$ and the Planck mass $M_P$ in terms of $M_S$, thus…
We consider heterotic string backgrounds in four-dimensional Minkowski space, where N=1 supersymmetry is spontaneously broken at a low scale m_{3/2} by a stringy Scherk-Schwarz mechanism. We review how the effective gauge couplings at…
Starting with two supersymmetric dual theories, we imagine adding a chiral perturbation that breaks supersymmetry dynamically. At low energy we then get two theories with soft supersymmetry-breaking terms that are generated dynamically.…
Embedding hidden sector supergravity models in the framework of string theory leads to the appearance of axion-like degrees of freedom. Among them is the model independent axion of heterotic string theory. It has a decay constant of order…
The nonassociative generalization of supersymmetry is considered. It is shown that the associator of four supersymmetry generators has the coefficient $\sim \hbar/ \ell_0^2$ where $\ell_0$ is some characteristic length. Two cases are…
We study string formation and dynamics in a scalar field theory with a global $U(1)$ symmetry. If a scalar field $\Phi$ is initially displaced from the minimum of a wine-bottle potential, even if uniformly over large spatial patches, small…
We work out the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tunable) positive cosmological constant, proposed by the authors in arXiv:1403.1534. It utilises a single chiral multiplet with a gauged shift…
We argue that deriving an effective field theory from string theory requires a Wilsonian perspective with a physical cutoff. Employing proper time regularization we demonstrate the decoupling of states and contrast this with what happens in…
Chiral cosmic strings are produced naturally at the end of inflation in supersymmetric models where the symmetry is broken via a D-term. Consequently in such theories, where both inflation and cosmic strings contribute to the density and…
We present a brief review of recent attempts to construct effective theories to describe the breaking of the electroweak symmetry in extensions of the Standard Model with new strongly interacting dynamics around the TeV scale. Particular…
The canonical Monte-Carlo algorithm for simulating the production of string-like topological defects at a phase transition is extended by introducing a distribution of domain sizes. A strong correlation is found between the fraction in the…
We modify and extend an earlier proposal by Brown and Teitelboim to relax the effective cosmological term by nucleation of branes coupled to a three-index gauge potential. Microscopic considerations from string/M theory suggest two major…
We construct complete sets of (open and closed string) covariant coherent state and mass eigenstate vertex operators in bosonic string theory. This construction can be used to study the evolution of fundamental cosmic strings as predicted…
Physical aspects of the thermofield dynamics of the D=10 heterotic string theory are exemplified through the infrared behaviour of the one-loop dual symmetric cosmological constant in association with the global phase structure of the…
The heterotic string theory, compactified to four dimensions, has been conjectured to have a duality symmetry (S duality) that transforms the dilaton nonlinearly. If valid, this symmetry could provide an important means of obtaining…
The weakly coupled vacuum of $E_8\otimes E_8$ heterotic string theory remains an attractive scenario for phenomenolgy and cosmology. The particle spectrum is reviewed and the issues of gauge coupling unification, dilaton stabilization and…
In this thesis we study physics beyond the standard model focusing on the quantum field theory in higher-dimensional space-time with some boundary terms. The boundary term causes nontrivial consequences about the vacuum structure of the…
We argue, at a very basic effective field theory level, that higher dimension operators in scalar theories that break symmetries at scales close to their ultraviolet completion cutoff, include terms that favour the breaking of translation…
We discuss the notion that quantum fields may induce an effective time-dependent cosmological constant which decays from a large initial value. It is shown that such cosmological models are viable in a non-de Sitter spacetime.