This book, now in its second edition, provides an introductory course on theoretical particle physics with the aim of filling the gap that exists between basic courses of classical and quantum mechanics and advanced courses of (relativistic) quantum mechanics and field theory. After a concise but comprehensive introduction to special relativity, key aspects of relativistic dynamics are covered and some elementary concepts of general relativity introduced. Basics of the theory of groups and Lie algebras are explained, with discussion of the group of rotations and the Lorentz and Poincaré groups. In addition, a concise account of representation theory and of tensor calculus is provided. Quantization of the electromagnetic field in the radiation range is fully discussed. The essentials of the Lagrangian and Hamiltonian formalisms are reviewed, proceeding from systems with a finite number of degrees of freedom and extending the discussion to fields. The final four chapters are devoted to development of the quantum field theory, ultimately introducing the graphical description of interaction processes by means of Feynman diagrams. The book will be of value for students seeking to understand the main concepts that form the basis of contemporary theoretical particle physics and also for engineers and lecturers. An Appendix on some special relativity effects is added.

Special Relativity.- Relativistic Dynamics.- The Equivalence Principle.- The Poincaré Group.- Maxwell Equations and Special Relativity.- Quantization of the Electromagnetic Field.- Group Representations and Lie Algebras.- Lagrangian and Hamiltonian Formalism.- Quantum Mechanics Formalism.- Relativistic Wave Equations.- Quantization of Boson and Fermion Fields.- Fields in Interaction.

Riccardo D'Auria was Full Professor of Theoretical Physics at the Politecnico de Torino, Italy, from 1986 to 2010 and is now Emeritus Professor.  He was Director of the Department of Physics at the university from 1995 to 1999. Professor D'Auria worked for several periods at CERN, and conducted research at the Universities of Princeton, Stony Brook, and UCLA in USA. At the last-mentioned university he gave courses to PhD students in Theoretical Physics. His research has focused on field theory, gravity, and models for the unification of all fundamental interactions, including dual models, gravity, supersymmetry, string theory, and supergravity. Together with P. Fré and L. Castellani he developed a new geometrical and group theoretical approach to the construction of any supergravity theory, usually known as rheonomy. Professor D'Auria is the author of 177 publications in international journals. He is co-author with L. Castellani and P. Fré of the three-volume book Supergravity and Superstrings: a Geometric Perspective (World Scientific, Singapore, 1990).

Mario Trigiante is Associate Professor in the Department of Physics at Politecnico de Torino, Italy. He gained his degree in Physics with honors (110/110) at the University of Pisa and in 1997 received his PhD in "Theory of Elementary Particles" at SISSA (International School for Advanced Studies), Trieste. After periods as a post-doc at the University of Wales in Swansea (UK) and the Spinoza Institute, Utrecht (the Netherlands), he joined the Politecnico di Torino as Adjunct Professor and took up his current position in 2008. In January 2014 he received the national qualification for the role of Full Professor. As well as teaching courses on Classical Mechanics, Thermodynamics, Electromagnetism, and Group Theory and Its Applications, he has conducted extensive research. He is the author of almost 100 scientific publications. He is review editor for the online, open access journal Frontiers and is a referee for several leading journals.