In this thesis a new formalism for Soft Collinear Effective Theory (SCET) is developed and a new calculation relevant to high-precision studies of Quantum Chromodynamics (QCD) involving the summation of Sudakov double logarithms is presented. The new formalism of SCET possesses certain desirable properties not manifest in the standard SCET formalism and is constructed in a framework consistent with the traditional effective field theory perspective. In particular, effective theory operators are organized in an expansion of inverse powers of the matching scale such that operator power counting is determined solely by dimensional analysis rather than requiring the introduction of an abstract power-counting parameter. In contrast to the standard formalism, the infrared degrees of freedom in the effective theory are not subdivided into separate modes determined by relative momentum scaling. The lack of separate collinear and ultrasoft modes is combined with a new subtraction prescription which plays the role of the zero-bin subtraction in the standard formalism. The distinction between different sources of subleading corrections in the effective theory is clarified in this formalism, allowing for a simpler organization of the calculation of these subleading corrections. This formalism is first demonstrated by applying it to the study of Deep Inelastic Scattering (DIS) in the endpoint limit, a process which has been treated several times using SCET. The result and intermediate steps of this calculation are contrasted with previous treatments to demonstrate the relevant features of the new formalism. Next, the calculation of subleading corrections to event shape distributions is addressed. An original calculation of operator anomalous dimensions is presented which will form the basis of future work addressing the current discrepancy in global determinations of the strong coupling constant.

Among resummation techniques for perturbative QCD in the context of collider and flavor physics, soft-collinear effective theory (SCET) has emerged as both a powerful and versatile tool, having been applied to a large variety of processes, from B-meson decays to jet production at the LHC. This book provides a concise, pedagogical introduction to this technique. It discusses the expansion of Feynman diagrams around the high-energy limit, followed by the explicit construction of the effective Lagrangian - first for a scalar theory, then for QCD. The underlying concepts are illustrated with the quark vector form factor at large momentum transfer, and the formalism is applied to compute soft-gluon resummation and to perform transverse-momentum resummation for the Drell-Yan process utilizing renormalization group evolution in SCET. Finally, the infrared structure of n-point gauge-theory amplitudes is analyzed by relating them to effective-theory operators. This text is suitable for graduate students and non-specialist researchers alike as it requires only basic knowledge of perturbative QCD.

This is the first advanced, systematic and comprehensive look at weak decays in the framework of gauge theories. Included is a large spectrum of topics, both theoretical and experimental. In addition to explicit advanced calculations of Feynman diagrams and the study of renormalization group strong interaction effects in weak decays, the book is devoted to the Standard Model Effective Theory, dominating present phenomenology in this field, and to new physics models with the goal of searching for new particles and interactions through quantum fluctuations. This book will benefit theorists, experimental researchers, and Ph.D. students working on flavour physics and weak decays as well as physicists interested in physics beyond the Standard Model. In its concern for the search for new phenomena at short distance scales through the interplay between theory and experiment, this book constitutes a travel guide to physics far beyond the scales explored by the Large Hadron Collider at CERN.

A modern introduction to quantum field theory for graduates, providing intuitive, physical explanations supported by real-world applications and homework problems.

This book is a broad-based text intended to help the growing student body interested in constructing and applying methods of effective field theory to solve problems in their research. It begins with a review of using symmetries to identify the relevant degrees of freedom in a problem, and then presents a variety of methods that can be used to construct various effective theories. A detailed discussion of canonical applications of effective field theory techniques with increasing complexity is given, including Fermi's weak interaction, heavy-quark effective theory, and soft-collinear effective theory. Applications of these techniques to study physics beyond the standard model, dark matter, and quantum and classical gravity are explored. Although most examples come from questions in high-energy physics, many of the methods can also be applied in condensed-matter settings. Appendices include various factoids from group theory and other topics that are used throughout the text, in an attempt to make the book self-contained.

Giving an accurate account of the concepts, theorems and their justification, this book is a systematic treatment of perturbative QCD. It relates the concepts to experimental data, giving strong motivations for the methods. Ideal for graduate students starting their work in high-energy physics, it will also interest experienced researchers.

A fully updated edition of the classic text by acclaimed physicist A. Zee Since it was first published, Quantum Field Theory in a Nutshell has quickly established itself as the most accessible and comprehensive introduction to this profound and deeply fascinating area of theoretical physics. Now in this fully revised and expanded edition, A. Zee covers the latest advances while providing a solid conceptual foundation for students to build on, making this the most up-to-date and modern textbook on quantum field theory available. This expanded edition features several additional chapters, as well as an entirely new section describing recent developments in quantum field theory such as gravitational waves, the helicity spinor formalism, on-shell gluon scattering, recursion relations for amplitudes with complex momenta, and the hidden connection between Yang-Mills theory and Einstein gravity. Zee also provides added exercises, explanations, and examples, as well as detailed appendices, solutions to selected exercises, and suggestions for further reading. The most accessible and comprehensive introductory textbook available Features a fully revised, updated, and expanded text Covers the latest exciting advances in the field Includes new exercises Offers a one-of-a-kind resource for students and researchers Leading universities that have adopted this book include: Arizona State University Boston University Brandeis University Brown University California Institute of Technology Carnegie Mellon College of William & Mary Cornell Harvard University Massachusetts Institute of Technology Northwestern University Ohio State University Princeton University Purdue University - Main Campus Rensselaer Polytechnic Institute Rutgers University - New Brunswick Stanford University University of California - Berkeley University of Central Florida University of Chicago University of Michigan University of Montreal University of Notre Dame Vanderbilt University Virginia Tech University

An Introduction to Quantum Field Theory is a textbook intended for the graduate physics course covering relativistic quantum mechanics, quantum electrodynamics, and Feynman diagrams. The authors make these subjects accessible through carefully worked examples illustrating the technical aspects of the subject, and intuitive explanations of what is going on behind the mathematics. After presenting the basics of quantum electrodynamics, the authors discuss the theory of renormalization and its relation to statistical mechanics, and introduce the renormalization group. This discussion sets the stage for a discussion of the physical principles that underlie the fundamental interactions of elementary particle physics and their description by gauge field theories.

This 2006 book uses the standard model as a vehicle for introducing quantum field theory.