# Questions tagged [quantum-field-theory]

Quantum Field Theory (QFT) is the theoretical framework describing the quantisation of classical fields which allows a Lorentz-invariant formulation of quantum mechanics. QFT is used both in high energy physics as well as condensed matter physics and closely related to statistical field theory. Use this tag for many-body quantum-mechanical problems and the theory of [tag:particle-physics]. Don’t combine with [tag:quantum-mechanics].

7,929 questions
Filter by
Sorted by
Tagged with
66 views

### Observables labelling one-particle states in Quantum Field Theory

I'm studying introductory QFT using the first volume of Weinberg's series, and i'm having problems in understanding how single particle states of the free theory are labelled, i.e. what observables ...
30 views

### How to calculate the effective potential of two interacting scalar field in QFT?

for the potential: $V=\lambda_h(h^2-v^2)^2+\lambda_s(s^2-w^2)^2+\lambda_{hs}h^2s^2$, where h and s are two real scalar fields and v and w are the vacuum expectation values of the two fields. The ...
37 views

71 views

### Tadpole diagrams in 1-loop massive scalar amplitudes?

Consider a massive scalar diagram such as or The loop momentum enters and exits the tadpole vertex, so that in the first diagram the momentum in the propagator connecting the two vertices is zero ...
91 views

63 views

### Why is the Jacobian factor for fermionic variables different from that for bosonic ones?

In Srednicki's textbook Quantum Field Theory, Section 77 discusses anomalies and the path integral for fermions. The path integral over the Dirac field is defined to be Z(A) \equiv \...
83 views

### Normal ordering by contour integral in CFT

In chapter 6 of Di Francesco, they introduce the normal ordering $$(AB)(w) = \oint_w \frac{ dz }{ 2\pi i (z-w) }A(z) B(w)\ .\tag{6.130}$$ So far so good. But then starting eq (6.139)  \oint_w \...
37 views

### Why is zero-point energy idolized as a good source of energy? [closed]

I've really only seen it in like liquid helium and I don't understand how it can hold the potential portrayed in the incredible movie by the main villian
100 views

### In relativistic QFT, is it ever possible that the bare mass be finite and equal to the physical mass?

In renormalization, one follows the philosophy that the bare mass is unobservable and could be infinite, and the physical mass comes from the pole of the two-point function. Is it possible that in any ...