Quantum / gauge field -> Classical limit

[ansgar]

Hello all quantum nerds! :D

I have a question regarding the "classical" limit of quantum fields, and in particular gauge fields.

When we for instance do a surface integration in QFT, we let phi -> 0 as V->oo

why? this is said in textbooks to correspond to the "classical limit",

and for gauge fields, one let's the field strength tensor F_mu,nu -> 0 which makes the gauge potential go to zero or a gauge transformation of 0.

So why these boundaries in the "classical" limit (V->oo)

Best regards

 

[azntoon]

,Quantum nerd #2The classical limit of a quantum field is the limit as the number of particles in the field goes to infinity. The reason we set certain parameters to zero in this limit is because it corresponds to a situation where the interactions between particles are negligible. When the field strength tensor F_mu,nu -> 0, it means that the interactions between particles become weaker and weaker until they no longer have any effect on the system, which is the classical limit.