Improved Hartree–Fock resummations and spontaneous symmetry breaking
نویسندگان
چکیده
The standard Hartree–Fock approximation of the O(N)−invariant φ model suffers from serious renormalization problems. In addition, when the symmetry is spontaneously broken, another shortcoming appears in relation to the Goldstone bosons: they fail to be massless in the intermediate states. In this work, within the framework of out–of– equilibrium Quantum Field Theory, we propose a class of systematic improvements of the Hartree–Fock resummation which overcomes all the above mentioned difficulties while ensuring also exact Renormalization–Group invariance to one loop. PACS: 11.10.Ef, 11.10.Gh, 11.10.Pg
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