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Seminars/Colloquia
Symmetry-improved CJT Effective Action
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Europe/Berlin
1141 (Hilbertraum) (Physik Department)
1141 (Hilbertraum)
Physik Department
East Side, Basement Floor
Description
The formalism introduced by Cornwall, Jackiw and Tomboulis (CJT) provides a systematic approach to consistently resumming non-perturbative effects in Quantum Field Theory (QFT). The CJT effective action has proven to be an extremely useful theoretical tool in thermal QFT, providing, among other things, the starting point for consistent descriptions of non-equilibrium phenomena.
One major limitation of the CJT effective action is that its loopwise expansion introduces residual violations of possible global symmetries, thus giving rise to massive Goldstone bosons in the spontaneously broken phase of the theory. We develop a novel symmetry-improved CJT formalism for consistently encoding global symmetries in a loopwise expansion. In our formalism, the extremal solutions of the fields and propagators are subject to additional constraints given by the Ward Identities.
We show that, unlike the existing approaches, our formalism satisfies a number of important field-theoretic properties, concerning phase transitions, absorptive effects and the effective potential. As an application of the symmetry-improved CJT formalism, we study the issue of infrared divergences of the Standard Model (SM) effective potential due to Goldstone bosons, which may affect the stability analyses of the SM, presenting some preliminary comparisons with partial diagrammatic resummations recently developed to address this problem.
One major limitation of the CJT effective action is that its loopwise expansion introduces residual violations of possible global symmetries, thus giving rise to massive Goldstone bosons in the spontaneously broken phase of the theory. We develop a novel symmetry-improved CJT formalism for consistently encoding global symmetries in a loopwise expansion. In our formalism, the extremal solutions of the fields and propagators are subject to additional constraints given by the Ward Identities.
We show that, unlike the existing approaches, our formalism satisfies a number of important field-theoretic properties, concerning phase transitions, absorptive effects and the effective potential. As an application of the symmetry-improved CJT formalism, we study the issue of infrared divergences of the Standard Model (SM) effective potential due to Goldstone bosons, which may affect the stability analyses of the SM, presenting some preliminary comparisons with partial diagrammatic resummations recently developed to address this problem.