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Constraints on New Vector Boson Mediated Electron-Nucleus Interactions from Spectroscopy Data of Polar Diatomic Molecules

Konstantin Gaul1,2,3,*, Lei Cong1,2,3,†, and Dmitry Budker1,2,3,4

  • *Contact author: konstantin.gaul@uni-mainz.de
  • †Contact author: conglei1@uni-mainz.de
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Phys. Rev. Lett. 136, 181805 – Published 6 May, 2026

DOI: https://doi.org/10.1103/d19m-s856

Abstract

A measurement of parity violation in the hyperfine structure of Ba138F19 [E. Altuntaş et al. Phys. Rev. Lett. 120, 142501 (2018)] is reinterpreted with electronic structure calculations in terms of beyond standard model vector boson mediated electron-nucleus interactions. Our results set constraints on previously unexplored, new boson mediated axial vector-vector nucleus-electron interactions. Similar bounds are obtained by analyzing the atomic parity violation experiment with Cs133. Moreover, we show that future experiments with cold heavy diatomic molecules like BaF137 or RaF225 can improve the present sensitivity to axial vector-vector nucleus-electron and nucleon-nucleus interactions by at least 2 orders of magnitude for large boson masses.

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Phys. Rev. Lett. 136, 181805– Published 6 May, 2026
  • Received 1 April 2025
  • Revised 17 March 2026
  • Accepted 30 March 2026
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