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  • Open Access

Torsion Balance Experiments Enable Direct Detection of Sub-eV Dark Matter

Shigeki Matsumoto1,*, Jie Sheng1,2,†, Chuan-Yang Xing3,‡, and Lin Zhu4,§

  • *Contact author: shigeki.matsumoto@ipmu.jp
  • †Contact author: jie.sheng@ipmu.jp
  • ‡Contact author: cyxing@upc.edu.cn
  • §Contact author: zhulin36@mail.hust.edu.cn
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Phys. Rev. Lett. 136, 121803 – Published 26 March, 2026

DOI: https://doi.org/10.1103/8lbh-lblh

Abstract

Light dark matter with sub-eV masses has a high number density in our Galaxy, and its scattering cross section with macroscopic objects can be significantly enhanced by coherence effects. Repeated scattering with a target object can induce a measurable acceleration. Torsion balance experiments with geometric asymmetry are, in principle, capable of detecting such signals. Our analysis shows that existing torsion balances designed to test the equivalence principle already place the most stringent constraints on DM-nucleon scattering in the (10−2,1)  eV mass range.

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Outline

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Phys. Rev. Lett. 136, 121803– Published 26 March, 2026
  • Received 24 June 2025
  • Revised 9 February 2026
  • Accepted 11 March 2026
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