Combined Test of Lorentz Symmetry in Short-Range Gravity

Tests of the Newtonian inverse square law at short range provide sensitive probes of Lorentz symmetry, violations of which can result in forces varying as the inverse sixth power of distance. We describe a recent search for Lorentz symmetry violation using the short-range experiments at the Huazhong University of Science and Technology (HUST) and Indiana University (IU) [1]. The HUST experiment consists of a torsion pendulum with a rotary source mass and dual compensation to reduce the Newtonian force. The IU experiment uses planar, 1 kHz mechanical oscillators with a stiff conducting shield in between them to suppress backgrounds. After over 2000 total hours of data collected with the former experiment and 40 hours with the latter, no evidence of signals above backgrounds are observed. These results imply constraints on the coefficients of Lorentz violation in the Standard Model Extension at the level of 10^-12 m⁴.

[1] C.-G. Shao, et al., Phys. Rev. Lett. 122 011102 (2019).