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A Search for Ultra-Light Vector Dark Matter with a Rotating Torsion Balance

M. P. Ross, E. A. Shaw, C. Gettings, S. K. Apple, I. A. Paulson, J. H. Gundlach

Abstract

We search for ultra-light vector dark matter interacting with a rotating torsion balance with a baryon minus lepton number composition dipole. Our search spans candidate masses in the ultra-low mass range from 1.3~$\times10^{-22}$ to 1.9~$\times10^{-18}$ eV. We set limits on the coupling strength to baryon minus lepton number for each dark matter candidate reaching a peak sensitivity of $g_{B-L} \leq 9 \times 10^{-26}$.

A Search for Ultra-Light Vector Dark Matter with a Rotating Torsion Balance

Abstract

We search for ultra-light vector dark matter interacting with a rotating torsion balance with a baryon minus lepton number composition dipole. Our search spans candidate masses in the ultra-low mass range from 1.3~ to 1.9~ eV. We set limits on the coupling strength to baryon minus lepton number for each dark matter candidate reaching a peak sensitivity of .
Paper Structure (3 equations, 4 figures, 1 table)

This paper contains 3 equations, 4 figures, 1 table.

Figures (4)

  • Figure 1: Diagram of the experiment showing the rotating torsion balance on the rotating Earth which is embedded in an ULDM field of unknown direction. The Z-component of the ULDM signal is modulated by the field's characteristic frequency and the rotation of the turntable while the X and Y components are additionally modulated by the Earth's rotation. Adapted from Reto Stöckli, Nazmi El Saleous, and Marit Jentoft-Nilsen, NASA GSFC.
  • Figure 2: Schematic of the rotating torsion balance apparatus. The torsion pendulum, vacuum system, and angular readout are mounted on a rotating air-bearing turntable. The tilt of the apparatus is measured by a pair of co-rotating tilt sensors and controlled by thermal expansion feet that the turntable rests on. Thermal gradients and changes of the temperature, magnetic field, and gravity gradients are controlled, shielded, and compensated for, respectively. Reprinted from Ref. ross2025probing.
  • Figure 3: Measured once per revolution torque amplitude over time. The zero time is set to January 1, 2024. Nearby construction activity and hardware failures caused many days of data to be dropped. However, at times when the construction activity was paused (weekends, holidays, etc.) the instrument was thermal noise limited.
  • Figure 4: Our 95%-confidence upper limits on the coupling constant of ULDM to B-L, $g_{B-L}$, along with previous limits set by MICROSCOPE frerick2024riding, shaw2022torsion, PhysRevLett.134.151001, LISA Pathfinder frerick2024riding, and the combined best direct detection limits.