Field theory Definition and 553 Threads

The question is more of a mathematical question then one about physics in the attached file between equations 6 and 7 it says "integration over the modes" i don't know how they go from the integration measure \int D\phi \rightarrow \int D\phi_1 D\phi_2...D\phi_N any advice would be...

what is the analogue of 'space is curved' in Quantum Field theory ?? if in General Relativity the main issue is that 'space is curved' what is the equivalence of it in Quantum mechanics ?? , for example how can QFT describe the curvature of space ??

wikipedia says http://en.wikipedia.org/wiki/Group_field_theory Overview Group field theory is a theory of quantum gravity. It is closely related to background independent quantum gravity approaches such as loop quantum gravity and spin foam and causal dynamic triangulation. It makes...

Does anyone know of quantum field theory lecture videos besides susskind and coleman.

Hi, could anyone explain to me why in effective field theory (as in ch29 srednicki), you look at diagrams with only k<\Lambda as external lines and k>\Lambda for your interal lines? why do these diagrams with say, 6 external legs of this type, equate to the constant c_6 say? In previous...

Can anybody suggest a good introductory book on CFT. I would like to learn String Theory; and this is my basic motivation to learn CFT...

can zeta regularization provide FINITENESS to quantum field theory ?? recently i came across (google) these papers http://vixra.org/abs/1003.0235 http://vixra.org/abs/1001.0042 http://vixra.org/abs/1001.0039 using the zeta regularization algorithm plus analytic continuation he...

I have pretty good handle on non-relativistic quantum mechanics, but I would like to learn about the Standard Model (Quantum Field Theory). What is the best introductory book and/or introductory article on QFT? Thanks Here are some I've heard of: Articles "[URL Model: An Introduction Authors...

The in the preface to his quantum field theory book, Srednicki mentions that there is a set of lectures by Ed Witten on quantum field theory for mathematicians that is available online. Does anyone know where this is?

Quantum Field Theory -- variational principle In non-relativistic quantum mechanics, the ground state energy (and wavefunction) can be found via the variational principle, where you take a function of the n particle positions and try to minimize the expectation value of that function with the...

Hi, I was looking for a book that would explain classical field theory in a Hamiltonian setting. What I mean by this is that there be no *actions* around, no *Lagrangians* and *Legendre transforms* to define the Hamiltonian and so on. What I'm looking fo is an exposition of (classical) field...

I know that the classical picture of QED is Coulomb interaction, magnetic interaction etc. But what does the classical phi^4 theory look like? In particular, do particles attract or repel each other in this theory? P.S. I'm surprised that my field theory books never discuss this. (At least in...

This may be a very basic question, but I've had now some background on the quantum theory, and I think I am missing something. Roughly speaking, I feel like the main difference is that quantizing involves going from field amplitudes to counting operators, implying that a quantum process involves...

What is the reasoning for saying that the scattering matrix in quantum field theory is unitary? Take the initial state to be an electron and a positron. All sorts of crazy products can result in the final state, from photons to Z's to Higgs to an electron/positron with different momenta, to...

Hi, I just created a wikipedia entry for group field theory here http://en.wikipedia.org/wiki/Group_field_theory I wrote "Group field theory is a theory of quantum gravity. It is closely related to background independent quantum gravity approaches such as loop quantum gravity and spin foam and...

Homework Statement Here is equation (2.68) (M^{ij})_{ab} = -i(\delta^i_a\delta^j_b - \delta^j_a\delta^i_b) Here is equation (2.69) (abbreviated) [M^{ij},M^{lm}]_{ab} = +i\delta^{jl}(M^{im})_{ab} +- ... The problem is to show that (2.68) implies (2.69) Homework Equations The...

At least one of us at this discussion board has expressed an interest in fractal modeling of spacetime, or of dynamics.* This paper by Calcagni may be suggestive of what form such an approach could take. http://arxiv.org/abs/1001.0571 Quantum field theory, gravity and cosmology in a fractal...

i have been given a problem for writing s matrix in second order perturbative theory for an interaction hamiltonian with phi 4 and phi 3 contributions. it is also given that our initial state is of 2 particles and final state is of three particles. now in solving that i have to take time...

If I take the massless limit of a massive field theory (e.g. considering cross-sections or other observables), do I always obtain the "right" massless theory?

I've been sick with mono for the past month and am trying to catch up in my Algebra class, but being so far behind I'm having a lot of trouble trying to grasp so much in so little time. Currently, I'm trying to get my head around field theory. Here are are few problems I've been working on. Is...

I've been sick with mono for the past month and am trying to catch up in my Algebra class, but being so far behind I'm having a lot of trouble trying to grasp so much in so little time. Currently, I'm trying to get my head around field theory. Here are are few problems I've been working on...

When people give the rules for the operator product expansion of fields in CFT, they always give the rule for the OPE of a product of two fields. But let's say that we have three fields. To be specific, consider the OPE of T(z_1) T(z_2) \Phi(z_3) where T is the energy-momentum tensor and \Phi...

Hi, Can someone briefly explain Field theory to me? Ie, in this book, it says that 1+1 = 0 when field : F (subscript 2) And you can create a finite field for any prime number p. I don't understand this lol. I also got this table: + 0 1 2 3 0 0 1 2 3 1 1 0 3 2 2 2 3 0 1 3 3 2 1 0...

Research in relativistic quantum mechanics proves, through a series of no-go theorems, that localized three (or four) dimensional particles cannot be the basic elements of reality. It is claimed that a field ontology can explain the appearance of three dimensional particles, but this new idea...

Hi there, I am currently studying Quantum Field Theory (well, for about 3 weeks isch), and it's really interesting and good fun! However, I would like to know how QFT relates Integrable QFT... I don't really know what it is. Can anyone tell me (i) The theoretical background of Integrable...

Hi there, I am currently studying Quantum Field Theory (well, for about 3 weeks isch), and it's really good fun! I would like to know how QFT relates Integrable QFT... I don't really know what it is. Can anyone tell me (i) The theoretical background of Integrable QFT (ii) The...

Hey everybody, since the previous thread got locked I thought I would open this thread as a place to discuss rigorous issues in quantum field theory, be it on the constructive or axiomatic side of things. I apologize if one is not supposed to start a discussion with posts from old threads...

Hi there, Can anyone explain to me what Conformal Field Theory really is in brief summary? I do not mind if anyone wants to go into technical details as I have some basic knowledge of quantum field theory already. Thank you

I have a theoretical question. When doing canonical quantization, and writing the equation for he time evolution of operator in Heisenberg picture, we make use of the statement that the external potential commutes with the field variables [V(\phi), \phi] = 0 This is obviously true if...

http://arxiv.org/abs/0905.3772 Group field theory renormalization - the 3d case: power counting of divergences Laurent Freidel, Razvan Gurau, Daniele Oriti "A 3D GFT graph G is a fat graph" http://arxiv.org/abs/hep-th/9306153 2D Gravity and Random Matrices P. Di Francesco, P. Ginsparg...

i need references on the topics. thanx

I don't understand the physical meaning of one of my dimensions/variables. Let there be a gravitational potential \phi (x_a), a=1,2,3. Equation of motions of a freely falling particle is: \frac{d^2 x_a}{d t} = - \frac{\partial \phi}{\partial x_a}. If there are 2 particles falling, family of...

I'm interested in reading Feynman's calculation for the perihelion advance of mercury that used quantum field theory calculations of graviton interactions. Anyone know where it's published or a good source on the web? Of course I've googled physics forums and haven't found an answer.

I have a few questions about this. My understanding is this: In the canonical approach to QFT there is an ambiguity in the order in which we write operators when calculating matrix elements. The different choices just correspond to different vacuum energies, which we are free to ignore since...

Hello Anyone got some introductory notes / books on Conformal Field Theory for someone who know Quantum Field Theory at the level of Peskin's book? cheers

I'm not sure if this is the right place for this question, so feel free to move it. Anyway, my question is, is there any good reason why the following field theory should be Weyl invariant in an arbitrary dimension d>1: S = \int d^d x \sqrt{g} \left( g^{\mu \nu} \partial_\mu \phi \partial_\nu...

What are some good books for non physicists on quantum field theory?

What is group field theory, and its relation LQG, CDT? There's no wiki article on gft. I am aware of the numerous articles on arix, could someone summarize what these articles mean?

For free quantum fields, there are two types of observables indexed by wave-number, \tilde{\hat{\phi}}(k), the Fourier transform of the local field, which can be written as a(-k)+a^\dagger(k), and projection operators such as a(k)^\dagger\left|0\right>\left<0\right|a(k), a(k_1)^\dagger...

Please let me know what lecture I have to previously take. I already took undergraduate level lecture of quantum mechanics and mathematical physics. And I also want to know that perturbation and scattering theory is hardly important on studying QFT..I'm so worry about that I didn't study...

Can anyone tell me if this is the basic concept behind effective field theories: 1) You begin with your original Lagrangian, and you want to construct an effective Lagrangian out of it. 2) You redefine your coupling constants in your original Lagrangian so that they include the integral...

Hi all, I bought a book recently of this title. I wanted this one to compliment the field theory book I have already (Peskin and Schroeder) because I find the latter a little hard to follow on my own (I am currently taking Relativistic Quantum Mechanics and will be taking QFT course at some...

I have a fairly good background in mathematics (algebra, analysis, topology, differential geometry)... and a good physics background (till QM, general relativity). I am looking to study Quantum Field Theory on my own. I do not intend to master QFT completely and all its techniques, but want to...

Sifting through ArXiv and other sources, I've found many documents on the topic of String Field Theory, perhaps the most extensive being by Thorn, 1989*. This brings up the question: Will String Field Theory evolve in popularity and perhaps outshine the more traditional String Theories? With...

I have a question about an equation in Maggiore's Modern Introd. to Quantum Field Theory p.52: \delta x^\mu = w^\mu_\nu x^\mu = \sum_{\rho < \sigma} A^\mu_{(\rho \sigma)} w^{\rho \sigma} where the A is defined as A^\mu_{(\rho \sigma)}=\delta^{\mu}_{\rho}x_\sigma - \delta^\mu_\sigma x_\rho...

Does anyone know if M-Theory is that same as Superstring Field Theory?

Hi everyone, This is my first post and I hope to get some better understanding of something that has been bugging me. I understand (global) gauge invariance in the sense that |\psi\rangle denotes the same (physical) state as e^{i\varphi}|\psi\rangle, or more generally, the physical state...

In quantum field theory a field is described by a multiparticles state? And, a single particle is itself a field?

Hi there people. Just wanted to bring up the idea of unified field theory and see what you think about it and so forth... create a dialogue or even a tryalogue. Is it or is it not the general crown jewels of science to find a theory that can be applied to any system and therefore predict...

I'm not sure if this post should go here or into the quantum physics forum, but I figure this can't be a bad place to put it. I have a few questions about canonical quantization and quantum field theories with interactions that I hope someone can answer. 1. I've been told that in Klein-Gordon...