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latentcorpse
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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!
http://www.damtp.cam.ac.uk/user/tong/qft/qft.pdf
Thank you!
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.
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.
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.
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.
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.