Related papers: String Models with Massive boson-fermion Degenerac…
We show that stable local cosmic strings are a generic prediction of supersymmetric models where supersymmetry is broken at scales within a few orders of magnitude of the weak scale and is fed down to the observable sector by gauge…
We investigate the string solutions and cosmological implications of the gauge ${\rm U(1)_Z}\,\times$ global ${\rm U(1)_{PQ}}$ model. With two hierarchical symmetry-breaking scales, the model exhibits three distinct string solutions: a…
I discuss a method for producing a quasi-realistic inter-generational quark mass hierarchy in string models. This approach involves non-Abelian singlet states developing intermediate scale vacuum expectation values. I summarize recent…
We argue that supersymmetric higher-dimension operators in the effective actions of M-theory and IIB string theory do not affect the maximally supersymmetric vacua: $adS_4\times S^7$ and $adS_7\times S^4$ in M-theory and $adS_5\times S^5$…
We study the observational constraints for the axion models in string theory which can successfully act as quintessence. The evolution of the universe in this model is sensitive to the initial value of the axion field. This initial value of…
We propose correspondences between 4d quantum field theories with N=2,1,0 (super)conformal invariance and Type IIB string theory on various orbifolds. We argue using the spacetime string theory, and check using the beta functions (exactly…
Supersymmetry breaking in string theory is expected to occur when moduli fields acquire non-trivial expectation values. In the early universe these fields start out displaced from their final destinations. I present some recent ideas about…
We review the prospect of obtaining tree-level de Sitter (dS) vacua and slow-roll inflation models in string compactifications. Restricting ourselves to the closed string sector and assuming the absence of NSNS-sources, we classify the…
Cosmic strings provide a radically different paradigm for the formation of structure to the prevailing inflationary one. They afford some extra technical complications: for example, the calculation of the power spectrum of matter and…
We provide a non-technical introduction to "misaligned supersymmetry", a generic phenomenon in string theory which describes how the arrangement of bosonic and fermionic states at all string energy levels conspires to preserve finite string…
With the aim of investigating the existence of an integrable elliptic deformation of strings on $\mathsf{AdS}_3 \times \mathsf{S}^3 \times \mathsf{T}^4$, we compute the tree-level worldsheet S-matrix of the elliptically-deformed bosonic…
We propose a new mechanism of spontaneous supersymmetry breaking. The existence of extra dimensions with nontrivial topology plays an important role. We investigate new features resulted from the mechanism in two simple supersymmetric Z_2…
We show that the existence of cosmic strings can be strongly constrained by the next generation of gravitational lensing surveys at radio frequencies. We focus on cosmic string loops, which simulations suggest would be far more numerous…
We describe the results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. For models with $\Gamma = \Omega h = 0.1 - 0.2$ and a cold dark matter…
We consider known examples of non-supersymmetric AdS$_7$ and AdS$_4$ solutions arising from compactifications of massive type IIA supergravity and study their stability, taking into account the coupling between closed- and open-string…
Early string theory described Bosonic particles at the real life Compton scale. Later developments to include Fermions initiated by Ramond and others have lead through Quantum Super Strings to M-theory operating at the as yet experimentally…
The first part of this review tries to provide a self-contained view of supersymmetry breaking from the bottom-up perspective. We thus describe N=1 supersymmetry in four dimensions, the Standard Model and the MSSM, with emphasis on the…
Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…
In string gas cosmology, extra dimensions are stabilised by a gas of strings. In the matter-dominated era, competition between matter pushing the extra dimensions to expand and the string gas pulling them back can lead to oscillations of…
Exploring MSSM parameter space after the discovery of Higgs Boson with mass 125 GeV naturally demands large top-squark mixing or large trilinear coupling parameter $A_t$ in particular, so as to avoid excessively heavy squark, specially for…