I am talking about perturbative quantum field theory. When calculating elements of correlation functions(which then I use to calculate S-matrix elements) one always comes up with connected and disconnected diagrams. These disconnected diagrams are usually dropped from the calculation and I...
Hello, I am currently studying spontaneous symmetry breaking in qft. Several textbooks I've read prove Goldstone's theorem under supposing that
1) There exists a continuous global symmetry under which the Lagrangian is invariant.
2) The vacuum state is not annihilated by the conserved...
Hello all. I was thinking about the famous cat thought experiment. I was wondering if anyone could explain to me(or point me in the right direction) what the various interpretations of quantum mechanics(copenhagen, many-worlds) say about this thought experiment from the cat's point of view...
Pressure as a single value is only well defined for a system in equilibrium, because if the system were not in equilibrium then the pressure would generally vary throughout the system. So unless you are studying non-equilibrium thermodynamics you will only compare pressures of systems in equilibrium
No I'm sorry if I wasn't clear. I understand the value of
\int \delta'(x)g(x)dx
I'm asking the value of
\int \delta'(g(x))\phi(x)dx
Where \phi(x) is the test function. Here it is not immediately obvious to me how to integrate by parts. I thought about this(but I am unsure of whether it is...
Hello I'm trying to figure out how to evaluate(in the distribution sense)
\delta'(g(x)). Where \delta(x) is the dirac delta function. Please notice that what I want to evaluate is not \frac{d}{dx}(\delta(g(x))) but the derivative of the delta function calculated in g(x).
If anyone could post...
I`ve read that the universes expansion is accelerating. To explain this we have introduced concept of Dark matter and energy.
However, Hubble's law: v = H*d means that a speed that separates two points is proportional to their distance. But since they are moving apart the distance becomes...
Please Correct me if I`m wrong, but isn't the E=mc^2 formula a way to say that matter and energy are essentially the same thing? By measuring time and distance in another system of units we could have c=1. This would make sense since it is a constant of the universe. If c=1 then E=m. So aren't...