A question about a derivation in QFT

Thread starter latentcorpse
Start date Dec 14, 2010
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Derivation Qft

In summary, a derivation in QFT is a mathematical process used to obtain equations of motion for fields and particles in quantum field theory. It involves taking the functional derivative of the action with respect to the fields. Derivations are important in QFT as they allow us to describe the dynamics of particles at the quantum level and make predictions about their behavior. The difference between classical and quantum derivations lies in the use of functional derivatives, which consider the quantum nature of particles. While derivations are a powerful tool, there are limitations to their use, such as in extreme conditions or when further refinements are needed to accurately describe particle behavior.

Dec 14, 2010

latentcorpse

How do we go from the first line in 6.17 to the second in these notes?
http://www.damtp.cam.ac.uk/user/tong/qft/qft.pdf
Thank you!

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Dec 14, 2010

betel

You will get it if you use 6.5. and 6.6.

1. What is a derivation in QFT?

A derivation in QFT refers to a mathematical process used to obtain equations of motion for fields in quantum field theory. This involves taking the functional derivative of the action with respect to the fields, which leads to the equations of motion for the fields.

2. Why is a derivation important in QFT?

Derivations are important in QFT because they allow us to describe the dynamics of fields and particles at the quantum level. By obtaining the equations of motion, we can understand how fields interact with each other and how particles behave in different quantum states.

3. What is the difference between a classical derivation and a quantum derivation in QFT?

In classical physics, derivations involve taking the partial derivative of a function with respect to its variables. However, in QFT, we use functional derivatives, which take into account the quantum nature of fields and particles. This allows us to describe the behavior of particles at the quantum level.

4. How do we use derivations in QFT to make predictions?

By using derivations, we can obtain the equations of motion for fields and particles in QFT. These equations can then be used to make predictions about the behavior of particles in different energy states and in various interactions. These predictions can be tested through experiments and compared to observational data.

5. Are there any limitations to using derivations in QFT?

While derivations are a powerful tool in QFT, there are limitations to their use. For example, they may not be applicable in certain extreme conditions, such as near a black hole or at very high energies. Additionally, the equations obtained through derivations may not always accurately describe the behavior of particles, and further refinements may be necessary.