# Tag Info

## New answers tagged field-theory

Accepted

### Invariance of general equations under Lorentz Transformation

I'll try to answer this. It might be inadequate but maybe a little useful. If there is an equation $A^\mu = B^\mu$ then the equation holds true in any frame, which is a postulate of special relativity....
• 196

### How to calculate the Hodge dual of a two-form defined in self-dual BF theory?

I found the solution thanks to the comments. There seems to be a factor of $\frac{1}{2}$ missing from the second term in the reference as well. Adding this factor will resolve the issue. \begin{align}\...
• 21
1 vote

### Does the Wigner little group classification of particles have consequences for classical field theory?

Depending on how you look at quantization, you could say there are consequences for classical field theory; whether there was first classical fields then they get quantized, or they were quantum all ...
• 817
1 vote

### How does Diagonalizing Mass Terms Affect the Lagrangian?

This is a response to the first part of your question, not related to the neutrino physics specifically. Suppose we start with a generic Lagrangian with $N$ scalar fields where both the kinetic and ...
• 49.8k

### Difference in definition of conserved current in Quantum Field Theory

Comparing the two resulting currents you see that they only differ by the addition of the $-F^\mu$ term. (The replacement of $X_a$ by $\delta \phi / \delta \alpha$ is only due to a different ...
• 1,039
Accepted

### Was the singularity a boson?

No. Within our best theories, this is incorrect. In general relativity, a singularity is a hole in spacetime (which is properly defined by means of geodesic incompleteness). It is not a particle and ...
• 21.3k

### Theorem in mechanics relating energy flow and momentum

It comes from the theory of relativity, not Newtonian mechanics, and it is not a theorem, but more of a generalization of what holds for energy and momentum of ordinary matter and EM field, to other ...
• 38.1k

### Theorem in mechanics relating energy flow and momentum

It is simply the statement that in General relativity the energy-momentum tensor $T^{\mu\nu}$ is symmetric: $T^{\mu\nu}=T^{\nu\mu}$. The quantity $T^{0\mu}$ is the density of the $\mu$-th ...
• 53.8k

### Conjugate momenta in field theory

TL;DR: The EOM of classical field theory are not those of classical mechanics because a field is a function of both space and time coordinates. Also, in field theory, space and time should be treated ...

• 24.5k