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  • Open Access

Generalized neutrino isocurvature

Christopher Gerlach1,*, Wolfram Ratzinger2,†, and Pedro Schwaller1,‡

  • *Contact author: cgerlach@uni-mainz.de
  • †Contact author: wolfram.ratzinger@weizmann.ac.il
  • ‡Contact author: pedro.schwaller@uni-mainz.de
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Phys. Rev. D 113, 083526 – Published 21 April, 2026

DOI: https://doi.org/10.1103/9wh7-9d7h

Abstract

Searches for neutrino isocurvature usually constrain a specific linear combination of isocurvature perturbations. In this work, we discuss realistic cosmological scenarios giving rise to neutrino isocurvature. We show that in general both neutrino and matter isocurvature perturbations are generated, whose ratio we parametrize by a newly introduced mixing angle. We obtain the first limits on this new mixing angle from PLANCK data, and discuss novel insights into the early Universe that could be provided by future measurements.

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Outline

Information

Phys. Rev. D 113, 083526– Published 21 April, 2026
  • Received 16 May 2025
  • Accepted 25 March 2026
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