What is Quantum field theory: Definition and 571 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.
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...
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...
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...
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...
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...
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...
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...
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...
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...
Hi all,
I have a question about the formulation of quantum field theories in curved spacetime. I'm still learning, and so I might not articulate this very well, but I'm wondering:
If a region of spacetime can warp and curve, dynamically changing its shape in response to changes in energy...
Hello Physics Forum
I will be taking a quantum field theory course next semester. I bought Mandl's book and Zee's
book and looked them a bit. I have also been talking to others that have taken the class in
previous semesters. I have a general idea of the failings of nonrelativistic...
\frac{1}{x-i\epsilon}=\frac{x}{x²+a²}+\frac{ia}{x²+a²}= P \frac{1}{x}+i pi \delta(x)
P means the principal value, a is possibly infinitesimal (?), i is the imaginary unit
Where does the pi, Dirac delta come from? What principal value?
It is from a quantum field theory book.
The question is as follows;
'A free quantum field theory is related to an infinite number of quantum mechanical harmonic oscillators as unit mass particles on springs with spring constants k, where k takes all values. Now imagine the following scenario: these particles also have non-zero...
I will be applying for grad school this Winter, but from January 2009-September 2009, I will be done with any course work and will not have any money to commute to my school to continue to do research. So I figured it would be a good opportunity to go further in my mathematics and physics...
When I read the security report from Cern (not that I am too worried), I came to something, which I do not fully understand:
As we all know, we are save from micro black holes created at the LHC because of Hawking radiation (for one of many reasons). The Cern people push this argument further...
Hi
I was wondering if anyone has a good introductory article about QFT applied to condensed matter physics.
I know a bit about condensed matter physics, and a bit of QFT applied to particle physics.
thanx
i've read that quantum field theory can be applied to condensed matter physics but i don't understand how: quantum field theory is the union of SR with QM but how is SR related to condensed matter physics? i understand that quantum field theory would be useful because it can describe...
"FIELDS"
by: WARREN SIEGEL
C. N. Yang Institute for Theoretical Physics
State University of New York at Stony Brook
Stony Brook, New York 11794-3840 USA
http://insti.physics.sunysb.edu/~siegel/Fields3.pdf
[SOLVED] Quantum Field Theory: Field Operators and Lorentz invariance
Hi there,
I am currently working my way through a book an QFT (Aitchison/Hey) and am a bit stuck on an important step in the derivation of the Feynman Propagator. My problem is obviously that I am not a hard core expert...
Non Commutative Cross-Section
hello, this is my first post here,
i have searched the web but i didnt find what i am looking for,so i hope i find it here.
i am looking for the formula of the cross section of compton scattring in the non commutative space-time .
I am to produce a research presentation for a class of Masters' physics students on the casimir force, going via a detailed treatment of the vacuum effects in conducting cavities, going on to explain some real phenomena and applications. What I am after is a good introductory text on quantum...
Homework Statement
A. Zee Quantum Field theory in a nutshell, p. 31. There is painfully little explanation on this page.
I'm okay with the action:
S(A) = \int d^4 x \mathcal{L} = \int d^4 x\{ \frac{1}{2}A_\mu [(\partial^2 +m^2)g^{\mu \nu}-\partial^\mu\partial^\nu]A_\nu + A_\mu J^\mu \}...
Quantum field theory or particle physics what first?
Hi at present I am confused whether i should try obtining a firm conceptual understanding of QFT before jumping to particle physics or whether aa very brief overview of QFT is enough ?
Since I'm very interested in General Relativity and Quantum field theory, I'd like to start a doctoral program abroad after my master study (I'm studying in Switzerland and will get my master degree in approximately 1.5 years).
I was surfing around in the internet and found for example the...
I was wondering what to read for quantum field theory and in what order if applicable: I have "qft in a nutshell" by zee, "intro to qft" by peskin, "qft" by rydern, and "advanced qft" by sakurai.
Hi,
I am curious about the following and I aim these questions to the people who do general relativity and uantum field theory over there.
What is the difference between field theory of general relativity and field theory of quantum field theory? Is the former only for study of gravitation...
I was wondering if anybody knew any good books that give an easy to understand quantum field theory. I am talking from a view point of a person who has read the third volume of the feynman lectures and quantum mechanics demystified. if this is not enough to even start a easy to understand...
I know that the vacuum in Quantum Field theory is not empty, but sometimes I find some people say that the particles are created from nothing because they are created from the vacuum , are those people expression a misleading?
On this forum, quantum field theory (QFT) is a part of this subforum (Quantum Physics), while particle physics is a subject of another forum. These two topics - QFT and particle physics - are clearly separated.
On the other hand, most textbooks on QFT are also textbooks on particle physics...
In my recent paper
http://xxx.lanl.gov/abs/0705.3542
entitled
"Is quantum field theory a genuine quantum theory? Foundational insights on particles and strings"
I argue the following:
Practically measurable quantities resulting from quantum field theory are not described by hermitian...
http://sites.google.com/site/winitzki/" a draft of an introductory textbook on quantum field theory in curved spacetime - free quantum fields in expanding universe, Unruh effect, Hawking radiation, also Casimir effect and some basic stuff on path integrals and effective action. The book is not...
I don't understand how Peskin & Schroeder can evaluate the integral on page 27 by having the real axis wrapping around branch cuts just like that. The picture of the contours are on page 28.
Hi all. I'm running a thread in the Philosophy section about rules of the universe etc but I'm stuck on a fundamental question which probably only a current quantum mechanics expert can answer.
In essence do the most current iterations of QF theory maintain that the ultimate and irreducible...
Hi,there! I want to study Quantum Field Theory but I don't know what book to use! I have a rather good background in quantum mechanics and electrodynamics, and I probably can gain access on the following books:
Brown L.S. : "Quantum Field Theory"
Peskin and Schroeder : "Introduction to Quantum...
I'm interested in teaching myself QFT. My BSc is in Mathematics and Physics, so I probably have a stronger mathematical background than the average physics graduate.
However, I'm assuming it's almost certainly not good enough.
What I am looking for is a way of sensibly teaching myself the...