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arXiv · 2607.28321

Systematic derivation of the Boltzmann equation for electroweak baryogenesis

Motoi Endo·Yushi Mura·Tenta Tsuji
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Abstract

We derive the Boltzmann equation for electroweak baryogenesis within a field-theoretical framework. We first algebraically solve the Kadanoff--Baym equations by incorporating the effects of gradients of the CP-violating bubble-wall background order by order. We then apply approximations and assumptions appropriate for electroweak baryogenesis and identify the on-shell parts of the solutions, which describe quasiparticle states propagating in a plasma. Using these on-shell solutions, we derive the Boltzmann equations for flavor-diagonal quasiparticle modes, while neglecting the off-diagonal components describing quantum coherence between different flavor modes. Our derivation generalizes previous field-theoretical treatments by retaining self-energy corrections, and our results are consistent with the known Boltzmann equations when these corrections are neglected. This framework provides a systematic and transparent derivation applicable to multi-flavor bosonic and fermionic systems.

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Motoi Endo, Yushi Mura, Tenta Tsuji. 2026-07-30. Systematic derivation of the Boltzmann equation for electroweak baryogenesis. https://arxiv.org/abs/2607.28321

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