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arXiv · 2606.02039

Tachyonic particle production: quantum 2PI formalism with momentum exchanging collisions

Kimmo Kainulainen·Sami Nurmi·Olli Väisänen
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Abstract

Oscillating spacetime curvature can drive particle production during reheating, whose accurate modeling requires the use of non-perturbative out-of-equilibrium methods. Tachyonic instabilities have previously been studied using 2-Particle Irreducible (2PI) formalism in the Hartree approximation, which however misses important momentum exchanging interactions. We present a self-consistent approximation scheme for reducing the non-local next-to-leading order 2PI equations of motion to local quantum kinetic equations, which can be solved with standard methods. We pay special attention to interactions involving unstable modes during tachyonic instabilities.

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Kimmo Kainulainen, Sami Nurmi, Olli Väisänen. 2026-06-01. Tachyonic particle production: quantum 2PI formalism with momentum exchanging collisions. https://arxiv.org/abs/2606.02039

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