From superstring theory to models with extra dimensions to dark matter and dark energy, a range of theoretically stimulating ideas have evolved for physics beyond the standard model. These developments have spawned a new area of physics that centers on the interplay between particle physics and cosmology—astroparticle physics. Providing the necessary theoretical background, Particle and Astroparticle Physics clearly presents the many recent advances that have occurred in these fields. Divided into five parts, the book begins with discussions on group and field theories. The second part summarizes the standard model of particle physics and includes some extensions to the model, such as neutrino masses and CP violation. The next section focuses on grand unified theories and supersymmetry. The book then discusses the general theory of relativity, higher dimensional theories of gravity, and superstring theory. It also introduces various novel ideas and models with extra dimensions and low-scale gravity. The last part of the book deals with astroparticle physics. After an introduction to cosmology, it covers several specialized topics, including baryogenesis, dark matter, dark energy, and brane cosmology. With numerous equations and detailed references, this lucid book explores the new physics beyond the standard model, showing that particle and astroparticle physics will together reveal unique insights in the next era of physics.