Vacuum to vacuum transition amplitude
131091
Srednicki's Path Integrals: Ground-State to Ground-State Transition Amplitude in the Presence of a Perturbation
11181
Counting degrees of freedom of gauge bosons
80596
Ambiguities in the energy-momentum tensor
26817
Quantum Field Theory from a mathematical point of view
155043
Substitution $\partial_\mu \to D_\mu \equiv \partial_\mu + ieA_\mu$ allows the introduction of electromagnetic interactions
6888
How to implement Einstein summation convention with differential operators
82894
Why cannot fermions have non-zero vacuum expectation value?
39244
References on the non-compositeness of the known elementary particles
5247
Physical meaning of non-trivial solutions of vacuum Einstein's field equations
150283
Prerequisites and introduction to string theory
31390
What prevents photons from getting mass from higher order Feynman diagrams
21186
Why is the second order perturbative correction to the ground state energy always down?
87914
Contradictory result for scalar-field propagator from Feynman rules and LSZ formula
89295
The interpretation of mass in quantum field theories
55412
Macroscopic quantum phenomena and tunneling
17414
Lagrangian of an effective potential
102564
Energy-momentum tensor transformation