I Understanding Electrons: The Difference Between QFT and QED

[Philipsmett]

What different between QFT and QED? In QFT electron is field quanta, what is electron in QED?

 

[Drakkith]

QED is a type of quantum field theory. QFT is just a way of modeling quantum phenomenon and doesn't necessarily refer to a specific model. I believe there are several gauge theories that are also quantum field theories, but I could be mistaken.

 

[jtbell]

Yes, QED (for electromagnetic interactions) is an example of a QFT. Other examples of QFTs are quantum chromodynamics (QCD) for the strong interaction, and electroweak theory, sometimes called quantum flavordynamics (QFD) for the unified electromagnetic and weak interactions.

 

[Philipsmett]

QED is a type of quantum field theory. QFT is just a way of modeling quantum phenomenon and doesn't necessarily refer to a specific model. I believe there are several gauge theories that are also quantum field theories, but I could be mistaken.

What is electron in QED? Is it field quanta?

 

[PeterDonis]

What is electron in QED? Is it field quanta?

QED is a QFT, so an electron in QED is whatever it is in QFT. And you already said what it is in QFT in your first post.

 

[Philipsmett]

QED is a QFT, so an electron in QED is whatever it is in QFT. And you already said what it is in QFT in your first post.

Why did Feynman say that the electron is a particle and not a field quanta?

 

[PeterDonis]

Why did Feynman say that the electron is a particle and not a field quanta?

A particle is a field quantum.

 

[Philipsmett]

A particle is a field quantum.

that is, the electron in QED is the excitation in the field?

 

[weirdoguy]

Yes, it's the excitation of electron field. Excitations of electromagnetic fields are photons. Maybe what he meant is that electrons are not exscitations of electromagnetic field.

 

[PeterDonis]

the electron in QED is the excitation in the field?

It's an excitation of the electron field. As @weirdoguy said. QED contains two fields, the electron field and the electromagnetic field. Photons are excitations of the electromagnetic field.

 

[CSnowden]

FYI, Feynman came over to the field viewpoint later in life - see reference in Julian Schwinger's Climbing the Mountain.