**A. Particle Physics and Cosmology**

To better understand the motivation behind inflation, it is important to outline a few aspects of particle physics. Often inflation is introduced in an abstract and unaesthetic manner. One speaks of an inflaton field, an arbitrary scalar field, for which there is no physical motivation. This is often the case because this type of introduction requires limited knowledge of the relevant topics. This includes, but is not limited to, the relativistic Schrödinger (Klein-Gordon) equation, the Dirac equation, scalar fields, symmetries, and group theory.

Since this paper is intended for undergraduates, a brief summary is presented on how one can pursue this knowledge in a qualitative and brief manner. A brief overview of the concepts in particle theory will be provided as needed. Thus, the reader is presented with a dilemma. One may choose to pause at this point and do a brief survey of the suggested texts or one may continue and plan to fill in the details at a later time. Both options have their advantages and disadvantages. I chose the former.

From the author's experience, a student should read through all of the references to get an intuitive picture of the theory and then go back and comb through the details and `hairy' calculations.

Three possible routes to obtaining the knowledge needed to continue are,

- Thorough Route (The one the author took)

[35, Chapter 15-16]-Introduction to cosmology with general relativity

[27, Chapter 13-14]-Elementary introduction to particle theory

[37, Chapter 1-6]-Introduction to relativistic quantum mechanics

[38]-Introduction to quantum field theory

[22], [9]-Bring the picture together - Fast Route
[22],
[9]-Bergström
extracts the
particle physics to the appendix, so as not to interfere with the
focus. Both of these books are excellent and I also recommend,
[13].
- Very fast route [9, [Appendix B and C]