This book presents the essentials culminating in the effective string theory of flux tubes in meticulous technical and conceptual detail. The book is divided into four parts. Part One provides historical background, while Part Two (consisting of 14 chapters) covers the passage from Heisenberg's S-matrix theory to String Theory. This includes non-perturbative LSZ formalism, dispersion relations, Regge poles, duality and dual resonance models.

Part Three offers a comprehensive analysis of QCD, focusing on important concepts like asymptotic freedom and quark confinement. The section...