Recent content by masteralien

But when you have an electron and positron collide they can either annihilate or scatter which one happens then. How would this initial quantum state evolve if its not in a superposition and could you elaborate a bit more on why superpositions are not possible.

In QFT one important calculation is the Scattering amplitude the overlap between an initial state and a final state due to an interaction. For example the S Matrix element for electron electron scattering is the overlap between an initial 2 electron state in the far past and a 2 electron state...

Also one more question can the Propagator G_2(x1-x2) be thought of as the Probability amplitude for a Particle to be found at spacetime point x1 created by a delta function source at spacetime point x2

What about expectation values for states which aren’t the vacuum like particle states can all those be computed with the n point functions

I see also is it true in principle any expectation value can be computed with the n point functions

In QFT the objects of interest are the n point Correlation functions which contain all the information about the theory and can be used to compute any expectation value in principle. However I cant figure out how to compute the vacuum energy from the correlation functions alone and cant find any...

What do you mean QFT is still a work in progress I thought we have the Standard Model and QED all sorted out? Could you elaborate a bit on why and how QFT is a work in progress I thought we had it figured out?

I understand its silly just was curious to see, as QFT has the Bethe Salpeter Equation for Hydrogen Bound States does String Theory have something similar. Also even if its inappropriate it can maybe be an interesting exercise. Also you say we dont have a complete String Theory how comes I...

Interesting is this solvable analytically

Yes I would like an A level answer

What about the Hydrogen Atom can that be modeled with String Theory

What about Bound States in String Theory also does String Theory have a notion of a “position space probability density” or some kind of equivalent

Idk have other things to do at the moment and thought I could ask this question to get a basic idea

Sure but I was asking more so about observables and quantities you compute like how in QFT you compute correlation functions with Feynman Diagrams. Is there a similar thing in String Theory. Also does String Theory have a notion like a one particle density or position space probability density...

I gave A because the question is advanced level as it involves String Theory