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Fate of θ12 under μ−τ reflection symmetry in light of the first JUNO results

Ranjeet Kumar*

  • *Contact author: kumarranjeet.drk@gmail.com
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Phys. Rev. D 113, 095012 – Published 6 May, 2026

DOI: https://doi.org/10.1103/1x8b-p916

Abstract

The recent Jiangmen Underground Neutrino Observatory (JUNO) measurements of θ12 and Δm212 open a new avenue for probing flavor symmetric structures in the lepton sector. Motivated by this, we study a model in which μ−τ reflection symmetry naturally emerges from an underlying A4 flavor symmetry within a type-II seesaw framework. Beyond its standard predictions of θ23=45° and δCP=±π/2, the framework yields testable predictions for θ12 that can be probed by JUNO. Two viable scenarios arise, one predicting sin2θ12≳0.335, which is strongly disfavored by the latest JUNO results. Correlations between θ12 and model parameters further enhance the model’s predictivity. Future measurements at DUNE and T2HK will provide complementary tests of this scenario.

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Phys. Rev. D 113, 095012– Published 6 May, 2026
  • Received 23 February 2026
  • Accepted 13 April 2026
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