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arXiv · 2604.05548

Cosmological collider signals of modular spontaneous CP breaking

Shuntaro Aoki·Alessandro Strumia
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Abstract

We consider a modular-invariant extension of the Standard Model. Assuming that the modulus is the inflaton, the CP-violating phases of the Yukawa couplings evolve during inflation. This dynamics favours a Higgs condensate, so that Standard Model fermions mediate a one-loop cosmological collider signal enhanced by chemical potentials. The effect appears too small for next-generation experiments. We provide precise expressions for Dirac fermions with chemical potentials in de Sitter.

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Shuntaro Aoki, Alessandro Strumia. 2026-04-07. Cosmological collider signals of modular spontaneous CP breaking. https://arxiv.org/abs/2604.05548

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