About three decades after the first experiments on deep inelastic lepton hadron scattering began to investigate the structure of hadrons, the history of this fruitful field of particle physics continues in the broad spectrum of research performed at the electron and positron proton collider HERA at DESY, where the multipurpose detectors ZEUS and H1 access ep scattering at a center of mass energy of 300 GeV and explore as yet uncharted kinematic realms of deep inelastic scattering. After the first years of data taking at HERA, each of the experiments has collected a total of roughly 40 pb 1 of e+p data, yielding sensitivity to deep inelastic e+p interactions at high four momentum transfers, Q2, where typi cal cross sections drop into the subpicobarn regime. This kinematic domain is characterized by electroweak unification, manifesting itself most markedly in the neutral and charged current cross sections, which approach an equal order of magnitude as Q2 rises above the square of the W and Z masses. Consequently, HERA allows, for the first time, studies of both types of pro cesses simultaneously with the same initial state conditions and in the same detector, and thus we can investigate the interplay of electroweak and strong forces governing the respective cross sections.

This book provides an up-to-date, self-contained account of deep inelastic scattering in high-energy physics, intended for graduate students and physicists new to the subject. It covers the classic results which led to the quark-parton model of hadrons and the establishment of quantum chromodynamics as the theory of the strong nuclear force, in addition to new vistas in the subject opened up by the electron-proton collider HERA. The extraction of parton momentum distribution functions, a key input for physics at hadron colliders such as the Tevatron at Fermi Lab and the Large Hadron Collider at CERN, is described in detail. The challenges of the HERA data at 'low x' are described and possible explanations in terms of gluon dynamics and other models outlined. Other chapters cover: jet production at large momentum transfer and the determination of the strong coupling constant, electroweak interactions at very high momentum transfers, the extension of deep inelastic techniques to include hadronic probes, a summary of fully polarised inelastic scattering and the spin structure of the nucleon, and finally a brief account of methods in searching for signals 'beyond the standard model'.