Introduction to the number of $e$-folds in slow-roll inflation

Abstract

In this review, a pedagogical introduction to the concepts of slow-roll inflationary Universe and number of $e$-folds is provided. In particular, the differences between the basic notion of number of $e$-folds ($N_e$), total number of $e$-folds ($N_T$) and number of $e$-folds before the end of inflation ($N$), are outlined. The proper application of the number of $e$-folds before the end of inflation is discussed both as a time-like variable for the scalar field evolution and as a key parameter for computing inflationary predictions.

arXiv comment23 pages, Review for the Special Issue Universe: Feature Papers 2024 - 'Cosmology'

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• Complex Inflaton Potentials with Nonminimal Coupling: Robust Inflation and Geometric Reheating