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Pure Spinor Formulation of the Superstring and Its Applications
The pure spinor formalism for the superstring has the advantage over the more conventional Ramond-Neveu-Schwarz formalism of being manifestly spacetime supersymmetric, which simplifies the computation of multi...
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Free Fermionic Constructions of Heterotic Strings
This chapter is an introduction to the Free Fermionic Formulation of string theory, with emphasis on heterotic model building. After a brief review of bosonization in two-dimensional conformal field theories, ...
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On Horizon Molecules and Entropy in Causal Sets
We review the different proposals and attempts to identify the “horizon molecules” that would give a kinematical estimation for the black hole entropy in causal set theory. The proposals are presented accordin...
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Asymptotic Safety and Cosmology
The asymptotic safety approach to quantum gravity provides a possible solution to the problem of the quantization of the gravitational field. It is based on the existence of an ultraviolet non-Gaussian fixed p...
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Superembedding Approach to Superstrings and Super-p-branes
We review a geometrical, so-called superembedding, approach to the description of the dynamics of point-like and extended supersymmetric objects (superbranes) in string theory. The approach is based on a super...
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D-Branes for Gauge Theories
D-branes are a very efficient tool to engineer gauge theories and study their properties. They have been instrumental in understanding the non-perturbative behavior of gauge theories, in studying their moduli ...
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Estimating the Manifold Dimension of Causal Sets
In a causal set theory of spacetime, on macroscopic scales, physically relevant causal sets must approximate spacetime manifolds. Methods for extracting manifold-like properties from causal sets are an active ...
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Corner Symmetry and Quantum Geometry
By virtue of the Noether theorems, the vast gauge redundancy of general relativity provides us with a rich algebra of boundary charges that generate physical symmetries. These charges are located at codimensio...
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Causality and Scattering Amplitudes in Nonlocal Gravity
A remarkable feature of weakly nonlocal gravitational theories (eventually coupled to matter), which are compatible with perturbative unitarity and finiteness at quantum level, is that they exhibit the same tr...
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11D Supergravity and Hidden Symmetries
We review the structure of maximal D = 11 and D = 10 supergravities. Upon dimensional reduction, these theories give rise to the unique maximal supergravities in all lower spacetime dimensions D < 10. In D dimens...
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D-brane and F-theory Model Building
We review recent progress in the construction of four-dimensional vacua of Type II string theory and F-theory which yield the Standard Model of particle physics (SM) or extensions thereof. In Type II orientifo...
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Lattice Quantum Gravity: EDT and CDT
This chapter contains an overview of the use of so-called Euclidean dynamical triangulations (EDT) and causal dynamical triangulations (CDT) as lattice regularizations of quantum gravity. The lattice regulariz...
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Extra Dimensions and Physics of Low-Scale Strings
This review aims to provide a very short and pedestrian introduction to some of the basics of extra-dimensional physics. The hope is to facilitate access and to be, in some respects, complementary to the many ...
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The Philosophy of Causal Set Theory
This chapter presents the most interesting philosophical issues as they arise in causal set theory. The first concerns the apparent disappearance of spacetime at the fundamental level. It shows how the looming...
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Heterotic Orbifold Models
We review efforts in string model building, focusing on the heterotic orbifold compactifications. We survey how one can, starting from an explicit string theory, obtain models which resemble Nature. These mode...
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Entanglement Entropy and Causal Set Theory
We review a formulation of the entanglement entropy of a quantum scalar field in terms of its spacetime two-point correlation functions. We discuss applications of this formulation to studying entanglement ent...
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Anomalies and the Green-Schwarz Mechanism
Anomalies are a very powerful tool in constraining theories beyond the standard model. We give a pedagogical overview of some topics illustrating the important role played by spacetime anomalies in string theo...
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\(\mathscr {N}\,{=}\,2\) Supergravities in Harmonic Superspace
Basics of N = 2 , 4 D \(\mathscr {N}\,{=}\,2, 4D\) ...
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The Causal Set Approach to the Problem of Quantum Gravity
Causal set theory (CST) is an approach to the problem of quantum gravity based on the twin hypotheses of fundamental spacetime discreteness and primitivity of the spacetime causal relation. We situate the chap...
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Covariant Growth Dynamics
The spacetime discreteness of causal set theory has enabled the formulation of novel spacetime dynamics. In these so-called “growth” dynamics, a causal set spacetime is generated probabilistically by means of ...