What Is The Iε For The S Matrix

Author : Holmfridur Sigridar Hannesdottir,Sebastian Mizera
Publisher : Springer Nature
Page : 165 pages
File Size : 48,8 Mb
Release : 2023-01-01
Category : Science
ISBN : 9783031182587

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What is the iε for the S-matrix? by Holmfridur Sigridar Hannesdottir,Sebastian Mizera Pdf

This book provides a modern perspective on the analytic structure of scattering amplitudes in quantum field theory, with the goal of understanding and exploiting consequences of unitarity, causality, and locality. It focuses on the question: Can the S-matrix be complexified in a way consistent with causality? The affirmative answer has been well understood since the 1960s, in the case of 2→2 scattering of the lightest particle in theories with a mass gap at low momentum transfer, where the S-matrix is analytic everywhere except at normal-threshold branch cuts. We ask whether an analogous picture extends to realistic theories, such as the Standard Model, that include massless fields, UV/IR divergences, and unstable particles. Especially in the presence of light states running in the loops, the traditional iε prescription for approaching physical regions might break down, because causality requirements for the individual Feynman diagrams can be mutually incompatible. We demonstrate that such analyticity problems are not in contradiction with unitarity. Instead, they should be thought of as finite-width effects that disappear in the idealized 2→2 scattering amplitudes with no unstable particles, but might persist at higher multiplicity. To fix these issues, we propose an iε-like prescription for deforming branch cuts in the space of Mandelstam invariants without modifying the analytic properties of the physical amplitude. This procedure results in a complex strip around the real part of the kinematic space, where the S-matrix remains causal. We illustrate all the points on explicit examples, both symbolically and numerically, in addition to giving a pedagogical introduction to the analytic properties of the perturbative S-matrix from a modern point of view. To help with the investigation of related questions, we introduce a number of tools, including holomorphic cutting rules, new approaches to dispersion relations, as well as formulae for local behavior of Feynman integrals near branch points. This book is well suited for anyone with knowledge of quantum field theory at a graduate level who wants to become familiar with the complex-analytic structure of Feynman integrals.

Author : James T. Cushing
Publisher : Cambridge University Press
Page : 436 pages
File Size : 54,9 Mb
Release : 1990
Category : Mathematics
ISBN : 0521381819

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Theory Construction and Selection in Modern Physics by James T. Cushing Pdf

Analyses what criteria should determine how scientific theories are selected and justified.

Author : Reiner M. Dreizler,Tom Kirchner,Cora S. Lüdde
Publisher : Springer Nature
Page : 236 pages
File Size : 47,8 Mb
Release : 2022-10-21
Category : Science
ISBN : 9783662655917

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Quantum Collision Theory of Nonrelativistic Particles by Reiner M. Dreizler,Tom Kirchner,Cora S. Lüdde Pdf

This book introduces the scattering theory of nonrelativistic systems, a standard tool for interpreting collision experiments with quantum particles at energies not too high. The goal is to explore the interaction between particles and their properties. The authors cover the basics of the theory through a detailed discussion of elastic scattering using the stationary Schrödinger equation and the Lippmann-Schwinger equation. These remarks are supplemented by a consideration of the time-dependent formulation of scattering theory. Selection rules for effective cross sections due to symmetries conditioned by the structure of the interparticle forces and the scattering of spin-polarized particles are discussed. The foundations for the treatment of inelastic processes are laid and explained by application to three-body and nucleotransfer processes. In all chapters, the more technical, mathematical aspect and the more physics-oriented explanations are separated as far as possible. The explanations are well comprehensible and suitable to introduce the reader to the physics of impact processes. This book is a translation of the original German 1st edition Streutheorie in der nichtrelativistischen Quantenmechanik by Reiner M. Dreizler, Tom Kirchner & Cora S. Lüdde, published by Springer-Verlag GmbH Germany, part of Springer Nature in 2018. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). The present version has been revised extensively with respect to technical and linguistic aspects by the authors. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors.

Author : Abdulaziz D. Alhaidari,Eric J. Heller,Hashim A. Yamani,Mohamed S. Abdelmonem
Publisher : Springer Science & Business Media
Page : 358 pages
File Size : 40,8 Mb
Release : 2008-03-20
Category : Science
ISBN : 9781402060731

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The J-Matrix Method by Abdulaziz D. Alhaidari,Eric J. Heller,Hashim A. Yamani,Mohamed S. Abdelmonem Pdf

Although introduced30 years ago, the J-matrix method has witnessed a resurgence of interest in the last few years. In fact, the interest never ceased, as some authors have found in this method an effective way of handling the continuous spectrum of scattering operators, in addition to other operators. The motivation behind the introduction of the J-matrix method will be presented in brief. The introduction of fast computing machines enabled theorists to perform cal- lations, although approximate, in a conveniently short period of time. This made it possible to study varied scenarios and models, and the effects that different possible parameters have on the ?nal results of such calculations. The ?rst area of research that bene?ted from this opportunity was the structural calculation of atomic and nuclear systems. The Hamiltonian element of the system was set up as a matrix in a convenient, ?nite, bound-state-like basis. A matrix of larger size resulted in a better con?guration interaction matrix that was subsequently diagonalized. The discrete energy eigenvalues thus obtained approximated the spectrum of the system, while the eigenfunctions approximated the wave function of the resulting discrete state. Structural theorists were delighted because they were able to obtain very accurate values for the lowest energy states of interest.

Author : Hayato Hirai
Publisher : Springer Nature
Page : 134 pages
File Size : 52,7 Mb
Release : 2021-07-17
Category : Science
ISBN : 9789811630453

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Towards Infrared Finite S-matrix in Quantum Field Theory by Hayato Hirai Pdf

This book presents the better understanding of infrared structures of particle scattering processes in quantum electrodynamics (QED) in four-dimensional spacetime. An S-matrix is the fundamental quantity in scattering theory. However, if a theory involves massless particles, such as QED and gravity, the conventional S-matrix has not been well defined due to the infrared divergence, and infrared dynamics thus needs to be understood in-depth to figure out the S-matrix. The book begins with introducing fundamental nature of the charge conservation law associated with asymptotic symmetry, and explaining its relations to soft theorems and memory effect. Subsequently it looks into an appropriate asymptotic state of the S-matrix without infrared divergences. The Faddeev-Kulish dressed state is known as a candidate of such a state, and its gauge invariant condition and its relation to the asymptotic symmetry are discussed. It offers an important building blocks for constructing the S-matrix without infrared divergences.

Author : Walter Greiner,Joachim Reinhardt
Publisher : Springer Science & Business Media
Page : 461 pages
File Size : 51,5 Mb
Release : 2008-11-26
Category : Computers
ISBN : 9783540875611

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Quantum Electrodynamics by Walter Greiner,Joachim Reinhardt Pdf

We are pleased by the positive resonance of our book which now necessitates a fourth edition. We have used this opportunity to implement corrections of misprints and amendments at several places, and to extend and improve the discussion of many of the exercises and examples. We hope that our presentation of the method of equivalent photons (Example 3. 17), the form factor of the electron (Example 5. 7), the infrared catastrophe (Example 5. 8) and the energy shift of atomic levels (Example 5. 9)arenow even better to understand. The new Exercise 5. 10 shows in detail how to arrive at the non-relativistic limit for the calculation of form factors. Moreover, we have brought up-to-date the Biographical Notes about physicists who have contributed to the dev- opment of quantum electrodynamics, and references to experimental tests of the t- ory. For example, there has been recent progress in the determination of the electric and magnetic form factors of the proton (discussed in Exercise 3. 5 on the Rosenbluth formula) and the Lamb shift of high-Z atoms (discussed in Example 5. 9 on the energy shift of atomic levels), while the experimental veri cation of the birefringence of the QED vacuum in a strong magnetic eld (Example 7. 8) remains unsettled and is a topic of active ongoing research.

Author : Rainer Dick
Publisher : Springer Nature
Page : 817 pages
File Size : 45,5 Mb
Release : 2020-11-09
Category : Science
ISBN : 9783030578701

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Advanced Quantum Mechanics by Rainer Dick Pdf

This textbook, now in an expanded third edition, emphasizes the importance of advanced quantum mechanics for materials science and all experimental techniques which employ photon absorption, emission, or scattering. Important aspects of introductory quantum mechanics are covered in the first seven chapters to make the subject self-contained and accessible for a wide audience. Advanced Quantum Mechanics: Materials and Photons can therefore be used for advanced undergraduate courses and introductory graduate courses which are targeted towards students with diverse academic backgrounds from the Natural Sciences or Engineering. To enhance this inclusive aspect of making the subject as accessible as possible, introductions to Lagrangian mechanics and the covariant formulation of electrodynamics are provided in appendices. This third edition includes 60 new exercises, new and improved illustrations, and new material on interpretations of quantum mechanics. Other special features include an introduction to Lagrangian field theory and an integrated discussion of transition amplitudes with discrete or continuous initial or final states. Once students have acquired an understanding of basic quantum mechanics and classical field theory, canonical field quantization is easy. Furthermore, the integrated discussion of transition amplitudes naturally leads to the notions of transition probabilities, decay rates, absorption cross sections and scattering cross sections, which are important for all experimental techniques that use photon probes.

Author : Steven C. Frautschi
Publisher : Unknown
Page : 220 pages
File Size : 44,6 Mb
Release : 1963
Category : Regge trajectories
ISBN : UCAL:B4523377

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Regge Poles and S-matrix Theory by Steven C. Frautschi Pdf

Author : V. P. Nair
Publisher : Springer Science & Business Media
Page : 560 pages
File Size : 51,6 Mb
Release : 2006-03-30
Category : Science
ISBN : 9780387250984

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Quantum Field Theory by V. P. Nair Pdf

Quantum field theory, which started with Paul Dirac’s work shortly after the discovery of quantum mechanics, has produced an impressive and important array of results. Quantum electrodynamics, with its extremely accurate and well-tested predictions, and the standard model of electroweak and chromodynamic (nuclear) forces are examples of successful theories. Field theory has also been applied to a variety of phenomena in condensed matter physics, including superconductivity, superfluidity and the quantum Hall effect. The concept of the renormalization group has given us a new perspective on field theory in general and on critical phenomena in particular. At this stage, a strong case can be made that quantum field theory is the mathematical and intellectual framework for describing and understanding all physical phenomena, except possibly for a quantum theory of gravity. Quantum Field Theory: A Modern Perspective presents Professor Nair’s view of certain topics in field theory loosely knit together as it grew out of courses on field theory and particle physics taught at Columbia University and the City College of CUNY. The first few chapters, up to Chapter 12, contain material that generally goes into any course on quantum field theory, although there are a few nuances of presentation which readers may find to be different from other books. This first part of the book can be used for a general course on field theory, omitting, perhaps, the last three sections in Chapter 3, the last two in Chapter 8 and sections 6 and 7 in Chapter 10. The remaining chapters cover some of the more modern developments over the last three decades, involving topological and geometrical features. The introduction given to the mathematical basis of this part of the discussion is necessarily brief and should be accompanied by books on the relevant mathematical topics as indicated in the bibliography. Professor Nair also concentrates on developments pertinent to a better understanding of the standard model. There is no discussion of supersymmetry, supergravity, developments in field theory inspired by string theory, etc. There is also no detailed discussion of the renormalization group. Each of these topics would require a book in its own right to do justice to the topic. Quantum Field Theory: A Modern Perspective serves as a portal to so many more topics of detailed and ongoing research, referring readers to more detailed treatments for many specific topics. The book also contains extensive references, providing readers a more comprehensive perspective on the literature and the historical development of the subject. V. Parameswaran Nair is Professor of Physics at City College of The City University of New York (CUNY). Professor Nair has held Visiting Professorships at The Abdus Salam International Center for Theoretical Physics, Rockefeller University, Institute for Advanced Study at Princeton, and Massachusetts Institute of Technology.

Author : Matthew D. Schwartz
Publisher : Cambridge University Press
Page : 869 pages
File Size : 42,5 Mb
Release : 2014
Category : Science
ISBN : 9781107034730

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Quantum Field Theory and the Standard Model by Matthew D. Schwartz Pdf

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

Author : Richard John Eden
Publisher : Unknown
Page : 287 pages
File Size : 42,6 Mb
Release : 1966
Category : S-matrix theory
ISBN : OCLC:622871472

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The Analytic S-Matrix, By R.J. Eden And Others by Richard John Eden Pdf

Author : Dzevad Belkic
Publisher : CRC Press
Page : 218 pages
File Size : 44,7 Mb
Release : 2020-01-15
Category : Science
ISBN : 9780429524967

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Principles of Quantum Scattering Theory by Dzevad Belkic Pdf

Scattering is one of the most powerful methods used to study the structure of matter, and many of the most important breakthroughs in physics have been made by means of scattering. Nearly a century has passed since the first investigations in this field, and the work undertaken since then has resulted in a rich literature encompassing both experimental and theoretical results. In scattering, one customarily studies collisions among nuclear, sub-nuclear, atomic or molecular particles, and as these are intrinsically quantum systems, it is logical that quantum mechanics is used as the basis for modern scattering theory. In Principles of Quantum Scattering Theory, the author judiciously combines physical intuition and mathematical rigour to present various selected principles of quantum scattering theory. As always in physics, experiment should be used to ultimately validate physical and mathematical modelling, and the author presents a number of exemplary illustrations, comparing theoretical and experimental cross sections in a selection of major inelastic ion-atom collisions at high non-relativistic energies. Quantum scattering theory, one of the most beautiful theories in physics, is also very rich in mathematics. Principles of Quantum Scattering Theory is intended primarily for graduate physics students, but also for non-specialist physicists for whom the clarity of exposition should aid comprehension of these mathematical complexities.

Author : Irinel Caprini
Publisher : Springer
Page : 130 pages
File Size : 50,6 Mb
Release : 2019-04-25
Category : Science
ISBN : 9783030189488

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Functional Analysis and Optimization Methods in Hadron Physics by Irinel Caprini Pdf

This book begins with a brief historical review of the early applications of standard dispersion relations in particle physics. It then presents the modern perspective within the Standard Model, emphasizing the relation of analyticity together with alternative tools applied to strong interactions, such as perturbative and lattice quantum chromodynamics (QCD), as well as chiral perturbation theory. The core of the book argues that, in order to improve the prediction of specific hadronic observables, it is often necessary to resort to methods of complex analysis more sophisticated than the simple Cauchy integral. Accordingly, a separate mathematical chapter is devoted to solving several functional analysis optimization problems. Their applications to physical amplitudes and form factors are discussed in the following chapters, which also demonstrate how to merge the analytic approach with statistical analysis tools. Given its scope, the book offers a valuable guide for researchers working in precision hadronic physics, as well as graduate students who are new to the field.

Author : Michael Peskin
Publisher : CRC Press
Page : 535 pages
File Size : 45,5 Mb
Release : 2018-04-27
Category : Science
ISBN : 9780429973802

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An Introduction To Quantum Field Theory, Student Economy Edition by Michael Peskin Pdf

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.

Author : Wolfgang Götze
Publisher : Oxford University Press on Demand
Page : 654 pages
File Size : 52,7 Mb
Release : 2009
Category : Science
ISBN : 9780199235346

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Complex Dynamics of Glass-Forming Liquids by Wolfgang Götze Pdf

Amorphous condensed matter can exhibit complex motions on time scales which extend up to those relevant for the functioning of biomaterials. The book presents the derivation of a microscopic theory for amorphous matter, which exhibits the evolution of such complex motions as a new paradigm of strongly interacting particle systems.e