Heidelberg 2022 – scientific programme
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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik
MP 7: Quantum field theory
MP 7.5: Talk
Wednesday, March 23, 2022, 18:05–18:25, MP-H5
Dyson series approach for understanding quadratic interactions — •Ayush Paliwal1 and Karl Henning Rehren2 — 1Institut für Theoretische Physik, Universität Göttingen — 2Institut für Theoretische Physik, Universität Göttingen
We analyze for general quadratic interactions whether, and in which sense, the two point function of the perturbed field, written in terms of the unperturbed field as a Dyson expansion, taken in the vacuum state of the unperturbed field, converges to the vacuum state of the perturbed field when the adiabatic limit is taken. The answer is affirmative in a number of simple cases, where the perturbed field is explicitly known. The result is not in conflict with Haag's theorem. It suggests to use the same method to compute the two-point function in some cases of interest where the perturbed field is not known.