Introduction to Modified Gravity

Preface
Contents
1 Einstein Gravity and the Need for Its Modification
2 Modifications of the Purely Geometric Sector
	2.1 Motivations
	2.2 upper R squaredR2-Gravity
	2.3 f left parenthesis upper R right parenthesisf(R)-Gravity
	2.4 Functions of Other Curvature Invariants
	2.5 Comments on Massive Gravity
	2.6 Conclusions
3 Scalar-Tensor Gravities
	3.1 General Review
	3.2 Chern-Simons Modified Gravity
		3.2.1 The Four-Dimensional Chern-Simons Modified Gravity Action
		3.2.2 Classical Solutions
		3.2.3 Perturbative Generation
	3.3 Brans-Dicke Gravity
	3.4 Galileons
	3.5 Conclusions
4 Vector-Tensor Gravities and Problem of Lorentz Symmetry Breaking in Gravity
	4.1 Introduction and Motivations
	4.2 Einstein-Aether Gravity
	4.3 Bumblebee Gravity
	4.4 Comments on Linearized Lorentz-Breaking Terms  in Gravity
	4.5 Conclusions
5 Horava-Lifshitz Gravity
	5.1 Introduction
	5.2 Basic Definitions
	5.3 Exact Solutions
	5.4 Modified Versions of HL Gravity
	5.5 Conclusions
6 Nonlocal Gravity
	6.1 Motivations
	6.2 Some Results in Non-gravitational Nonlocal Theories
	6.3 Classical Solutions in Nonlocal Gravity Models
	6.4 Conclusions
7 Comments on Non-Riemannian Gravity
	7.1 Introduction
	7.2 Metric-Affine Geometrical Tools
	7.3 Fermions in a Riemann-Cartan Space
		7.3.1 General Definitions
		7.3.2 One-Loop Induced Nieh-Yan Topological Term
	7.4 Metric-Affine Bumblebee Model
		7.4.1 Field Equations
		7.4.2 Spinor Sector and Spontaneous Lorentz Symmetry Breaking
		7.4.3 One-Loop Divergent Contributions to the Fermionic Effective Action
	7.5 Conclusions
8 Summary
References
Index