This book introduces quantum field theory, together with its most important applications to cosmology and astroparticle physics, in a coherent framework. The path integral approach is employed right from the start, and the use of Green functions and generating functionals is illustrated first in quantum mechanics and then in scalar field theory. Massless spin one and two fields are discussed on an equal footing, and gravity is presented as a gauge theory in close analogy with the Yang-Mills case. Concepts relevant to modern research such as helicity methods, effective theories, decoupling, or the stability of the electroweak vacuum are introduced. Various applications such as topological defects, dark matter, baryogenesis, processes in external gravitational fields, inflation and black holes help students to bridge the gap between undergraduate courses and the research literature.

"This book treats two fields of physics that are usually taught separately quantum field theory (QFT) on one side and cosmology and gravitation on the other in a more unified manner. This volume can serve as a textbook for courses in QFT, astroparticle physics and cosmology, and students interested in working at the interface between these fields can certainly appreciate the uncommon approach used." - CERN Courier

"Recommended." - CHOICE

"As a classical textbook, it contains everything to facilitate the preparation of a lecture course or a self-study: many pictures and a lot of exercises. This book is amazingly self-contained. All definitions and all numbers are here. Most of the computations are done from the beginning till the end in all details." - Dmitri V. Vassilevich, Mathematical Review Clippings