What is Quantum field theory: Definition and 567 Discussions

In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasiparticles.
QFT treats particles as excited states (also called quanta) of their underlying quantum fields, which are more fundamental than the particles. Interactions between particles are described by interaction terms in the Lagrangian involving their corresponding quantum fields. Each interaction can be visually represented by Feynman diagrams according to perturbation theory in quantum mechanics.

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  1. E

    Fields in quantum field theory

    Hi, I'm a little confused about the nature of fields in quantum field theory. I sometimes see people make reference to an "electron field" or other matter field of some sort, and in my understanding, in quantum field theory, ALL the different fundamental particles can be represented as...
  2. M

    Quantum Field Theory Book(s)

    Can anybody recommend some good quantum field theory books for introduction to the subject? I am already familiar with some of the techniques from applications to statistical mechanics, but I would like to see them in a different context.
  3. V

    Superconductivity and Quantum Field Theory

    Why do theories of superconductivity need to be quantum field theories with 2nd quantisation? Isn't first quantisation enough?
  4. F

    Questions on An Introduction to Quantum Field Theory by Peskin and Schroeder

    Greetings--I have a few questions from An Introduction to Quantum Field Theory by Peskin and Schroeder. Note: I'm not sure how to construct the contraction symbol using \LaTeX, so instead I will use the following cumbersome convention: \overbrace{\psi(x)\overline{\psi(y)}}=S_F(x-y), they...
  5. D

    Exploring Quantum Field Theory: A Student's Perspective

    At my physics faculty there is this magazine that comes out once every three months. I wrote an article about GR for it. Introducing not only the concepts but also some mathematics. I explained the field equations and derived some implications of the Schwarzschild metric. I could do this because...
  6. V

    ANN: quantum field theory course.

    Hello All, Hendrik van Hees just started a qft course. Here's his announcement: We just started an online qft theory course, reading along Zee's textbook. Soon, it will be provided as a an online course at the supersymmetry web page: http://www.superstringtheory.com/ Since the...
  7. G

    Two concepts about quantum electrodynamics and quantum field theory

    One question has disturbed me long time, I don't know the distinction between quantum electrodynamics and quantum field theory. By the way, which quantum field theory or quantum electrodynamics textbook is prefer?
  8. pellman

    Position and momentum operators in quantum field theory

    In short, the question is, how is the position operator related to the position-parameters of a quantum field ψ(x)? For instance, consider a quantum-mechanical state of two particles |Ψ>. This can be expanded in terms of the position eigenstates |x1,x2> to give the position representation...
  9. R

    Quantum Field Theory: A Modern Introduction

    I noticed that some copies of this book are available at Amazon for as low as $13.00, and increbible price. I just ordered a copy for my self. If anyone else is interested, they are here:
  10. M

    Is There a Speed Limit for Spacetime Expansion in Quantum Field Theory?

    The propagation of something, photon or particle, can have many possible paths, thus the Feynman path integral formulation of quantum mechanics. The initial position is relatively fixed and the final position is relatively fixed (compared to all of space). But it's path from beginning to end can...
  11. MC363A

    Learn Quantum Field Theory: Beginner Guide

    Does anyony know of a good, cheap (Perhaps Free :biggrin: ) book that will teach me the basics of quantum field theory. I am a very new beginner, so I will need something simple please. thanks.
  12. K

    Quantum Field Theory: What if Photon Made from Multiple Particles?

    If a photon was made from more than one particle, how would quantum field theory be modified?
  13. V

    Good quantum field theory text?

    could anyone suggest a good quantum field theory text? i mean a text for a beginner who is familiar with basic quantum mechanics...also, since i am going to study it by myself( i am not taking a physics course ), a text that is simple in language and informal would be great.(i mean, like...
  14. K

    Mathematica Mathematical foundation of quantum field theory

    Greetings, I have question regarding the mathematica foundations of QFT. As I understand, the "regular" QM (Schrödinger, Heisenberg...) been developped so that the math underlying it checks out. Is this the case for QFT, or is the theory still "iffy" at points? I know it works well...
  15. marcus

    Topological Quantum Field Theory, definition

    I believe that the Axioms for TQFT were set out by Atiyah in 1990 and that one of the equivalent definitions of a TQFT is in category terms: a TQFT is a functor from the category of n-dimensional cobordisms to the category of Hilbert spaces, satisfying certain conditions. Is anyone familiar...
  16. E

    About the action S in quantum field theory

    Let,s suppose we have a Hamiltonian H so we can construct the action by H+dS/dt then why no use the action to solve the problem of quantization of non renormalizable theories?..
  17. quantumdude

    Quantum Field Theory: An Introduction to Physics Beyond the Standard Model

    Hello everyone! This is the rebirth of my thread in PF v2.0 entitled "Do you know QM and SR?" Since I started that thread, a 2nd edition of the book (Warren Siegel's Fields) has been released. The url is: http://xxx.lanl.gov/pdf/hep-th/9912205 I'll post some of the more useful comments from...
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