To solve bound state problems in Quantum Field Theory (QFT), particularly for systems like electron-positron atoms, one must address the limitations of Fock space and the conventional definitions of wave functions and potentials. The recommended approach involves fitting an interaction potential that aligns with QFT-calculated scattering amplitudes, as outlined in Berestetskii, Lifgarbagez, and Pitaevskii's "Quantum Electrodynamics," specifically sections 83 and 84. This fitting process includes a combination of Coulomb, spin-orbit, and other relativistic corrections, which effectively reproduces bound states in the second perturbation order. Further insights can be gained from chapter 10 of the referenced arXiv paper.
PREREQUISITESPhysicists, particularly those specializing in Quantum Field Theory and quantum electrodynamics, as well as researchers working on bound state problems in particle physics.
Prathyush said:How does one solve bound state problems in QFT(like an electron positron atom)? How does one identify the space of states. The Fock space seems to lose it definition when a bound state problem is discussed. There is also no meaning to wave functions or potentials that are used in standard quantum mechanics.