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Toward First Detection of the Solar Mikheyev-Smirnov-Wolfenstein Transition with JUNO

Obada Nairat1,2,*, John F. Beacom1,2,3,†, Kevin J. Kelly4,‡, and Shirley Weishi Li5,§

  • *Contact author: nairat.2@osu.edu
  • †Contact author: beacom.7@osu.edu
  • ‡Contact author: kjkelly@tamu.edu
  • §Contact author: shirley.li@uci.edu
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Phys. Rev. Lett. 137, 081801 – Published 19 August, 2026

DOI: https://doi.org/10.1103/qhr8-qhhp

Abstract

Matter-induced neutrino flavor mixing (the Mikheyev-Smirnov-Wolfenstein, or MSW, effect) is a central prediction of the neutrino mixing framework, but it has not been conclusively observed. Direct observation of the energy-dependent MSW transition in the solar electron-neutrino survival probability would solve this, but backgrounds have been prohibitive. We show that our new technique for suppressing muon-induced spallation backgrounds will allow JUNO to measure the MSW transition at >4σ significance in 10 years. This would strongly support upcoming multibillion-dollar next-generation experiments and their goals in cementing the neutrino mixing framework.

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New spallation background rejection techniques to greatly improve the solar neutrino sensitivity of JUNO

Obada Nairat, John F. Beacom, and Shirley Weishi Li
Phys. Rev. D 114, 043047 (2026)

Article Text

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Phys. Rev. Lett. 137, 081801– Published 19 August, 2026
  • Received 31 January 2026
  • Revised 18 June 2026
  • Accepted 14 July 2026
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