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Elementary Particles, Quantum Field Theory
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Effective Field Theory and Applications
In this chapter, we will review the field-theoretic treatment of general relativity based on an effective field theory extension of the Einstein-Hilbert action. This pragmatic route to low-energy quantum effec...
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Toward the Emergence of Continuum Spacetime in Causal Set Theory
In causal set theory (CST), the continuum spacetime manifold is postulated to be a low-energy approximation of a more fundamental discrete sub-structure of a locally finite partial ordered set, called as the c...
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Nonlocal Gauge Theories Including Quantum Gravity
In this chapter we review nonlocal field theory (infinite derivative field theory). We start with the discussion of the main peculiarities of nonlocal field theory on the example of d = 4 scalar ϕ4 model. The non...
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Causal Set Cosmology
In the absence of direct experimental/observational data and viable low-energy limits, theories of quantum gravity should look toward cosmology as their testing ground. Presented here is a summary of ideas roo...
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Quantum Field Theory on Causal Sets
We give a broad overview of a construction of a theory for matter on fixed causal set backgrounds. We introduce the Sorkin-Johnston formalism for a free (real) scalar field theory that is applicable to regions...
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The AdS/CFT Correspondence
A short introduction to the Anti-de-Sitter/Conformal Field Theory correspondence and related ideas.
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Computer Simulations of Causal Sets
This review introduces Markov Chain Monte Carlo simulations in causal set theory, with a focus on the study of the 2d orders. It will first introduce the Benincasa-Dowker action on causal sets and cover some m...
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Perturbative Approaches to Nonperturbative Quantum Gravity
We discuss the birth of the nonperturbative approach to quantum gravity known as quantum Einstein gravity, in which the gravitational interactions are conjectured to be asymptotically safe. The interactions ar...
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Quantum Curvature as Key to the Quantum Universe
Curvature is a key notion in general relativity, characterizing the local physical properties of spacetime. By contrast, the concept of curvature has received scant attention in nonperturbative quantum gravity...
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Interacting Quantum Scalar Field Theory on a Causal Set
We introduce ϕ4 interacting real scalar quantum field theory (QFT) on causal sets. We consider both the canonical framework of causal set free QFT, involving a Hilbert space and operators and so on, and the doubl...
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Black Holes in Non-local Gravity
In this chapter, we present a status report of black hole-like solutions in non-local theories of gravity in which the Lagrangians are at least quadratic in curvature and contain specific non-polynomial (i.e.,...
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One-Loop Divergences in Higher-Derivative Gravity
We give a review of the one-loop divergences in higher-derivative gravity theories. We first make the bilinear expansion in the quantum fluctuation on arbitrary backgrounds, introduce a higher-derivative gauge...
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Scalar Fields in Four-Dimensional CDT
The model of Causal Dynamical Triangulations (CDT) is a non-perturbative and background-independent approach to the quantum theory of gravity. It provides a lattice regularization of the formal gravitational p...
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Supergravity: Application in Particle Physics
We provide a pedagogical introduction to N = 1 supergravity/supersymmetry in relation to particle physics. The various steps in the construction of a generic N = 1 supergravity model are briefly described, and we...
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The Causality Road from Dynamical Triangulations to Quantum Gravity that Describes Our Universe
It is shown how one, guided by causality, starting from the so-called dynamical triangulations, is led to a candidate of quantum gravity that describes our Universe. This theory is based on W and Jordan algebras....
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The Background Information About Perturbative Quantum Gravity
The purpose of this chapter is to give a general introduction and status review on the perturbative approach to quantum gravity (QG). This text is a modified version of the corresponding chapters of Part II of...
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Spin Foams: Foundations
Spin foams provide a framework for the dynamics of loop quantum gravity that is manifestly covariant under the full four-dimensional diffeomorphism symmetry group of general relativity. In this way, they compl...
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Quantum Cosmological Gravitational Waves?
General relativity and its cosmological solution predict the existence of tensor modes of perturbations evolving on top of our Friedman-Lemaître-Robertson-Walker expanding Universe. Being gauge invariant and n...
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Pure Spinors in Classical and Quantum Supergravity
This is an overview of the method of pure spinor superfields, written for Handbook of Quantum Gravity, eds. C. Bambi, L. Modesto, and I. Shapiro. The main focus is on the use of the formalism in maximal supergrav...
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From Trees to Gravity
In this article, we study two related models of quantum geometry: generic random trees and two-dimensional causal triangulations. The Hausdorff and spectral dimensions that arise in these models are calculated...
