Related papers: The hyperplane string, RCFTs, and the swampland
We are inspired by the facts that M-theory may reconcile the supersymmetric GUT scale with that of quantum gravity, and that it provides new avenues for low-energy supersymmetry breaking, to re-examine a flipped SU(5) model that has been…
We show how to make a topological string theory starting from an $N=4$ superconformal theory. The critical dimension for this theory is $\hat c= 2$ ($c=6$). It is shown that superstrings (in both the RNS and GS formulations) and critical…
It was recently pointed out that the cosmological constant (even metastable one) belongs to the so-called "swampland" and hence cannot be obtained as the low-energy limit of string theory that requires $|\nabla V| > c V$. If true, the dark…
In this semi-technical review we discuss string theory (and all that goes by that name) as a framework for a quantum theory of gravity. This is a new paradigm in theoretical physics that goes beyond relativistic quantum field theory. We…
We describe string-theory and $d=11$ supergravity solutions involving symmetric spaces of constant negative curvature. Many examples of non-supersymmetric string compactifications on hyperbolic spaces $H_r$ of finite volume are given in…
We perform a systematic study of the applicability of swampland constraints to theories of localized gravity. We find that these gravity theories can violate swampland constraints, but can be reconciled with them when coupled to a…
I summarize and discuss some recent results on formulating actions of six-dimensional superconformal field theories using the language of higher gauge theory. The latter guarantees mathematical consistency of our constructions and we review…
We extend the system of ungauged N=2, d=4 supergravity coupled to vector multiplets and hypermultiplets with 2-form potentials. The maximal number of 2-form potentials that one may introduce is equal to the number of isometries of either…
The four-dimensional superstring solutions define at low energy effective supergravity theories. A class of them extends successfully the validity of the standard model up to the string scale (${\cal O}(10^{17})~TeV$). We stress the…
There is evidence that string theory possesses a large discretuum of stable and/or metastable ground states, with zero or four supersymmetries in four dimensions. I discuss critically the nature of this evidence. Assuming this "landscape"…
This thesis consists of two parts. In the first part we study some topics in $\mathcal{N}=1$ supersymmeric gauge theory and the relation to matrix models. We review the relevant non-perturbative techniques for computing effective…
One of the main goals of the field of string phenomenology is to describe the properties of our spacetime in low-energy effective models related to and consistent with string theory. It is known that our universe undergoes accelerated…
We systematically include central charges into supersymmetric quantum mechanics formulated on curved Euclidean spaces, and explain how the background geometry manifests itself on states of the theory. In particular, we show in detail how,…
We continue the study of heterotic non-Abelian BPS-saturated flux tubes (strings). Previously, such solutions were obtained [1] in a particular U(2) gauge theory: N=2 supersymmetric QCD deformed by superpotential terms of a special type…
We consider a conformal system of a string and a particle defined in D=10+2 space-time dimensions. The extra time-like dimension is a gauge artifact and can be eliminated by choosing a gauge in which the SO(10,1) Lorentz symmetry is…
Possible ways of constructing extended fermionic strings with $N=4$ world-sheet supersymmetry are reviewed. String theory constraints form, in general, a non-linear quasi(super)conformal algebra, and can have conformal dimensions $\geq 1$.…
String theory is the most promising candidate for the theory unifying all interactions including gravity. It has an extremely difficult dynamics. Therefore, it is useful to study some its simplifications. One of them is non-critical string…
We construct a two-parameter four-dimensional non-BPS NS-NS smooth microstate solution that asymptotes to flat spacetime with a linear dilaton in type II superstring theory. From the microscopic point of view, the background is made out of…
We show that the boundary string field theory (BSFT) on unstable D0-branes in 2d string theory is equivalent to the double scaled c=1 matrix model (i.e. quadratic action), even though we naively expect many interaction terms in BSFT. It is…
String theoretical ideas might be relevant for particle physics model building. Ideally one would hope to find a unified theory of all fundamental interactions. There are only few consistent string theories in D=10 or 11 space-time…