Searching for scalar field dark matter with short-range gravity experiments

The nature of dark matter remains a mystery, although enormous efforts have been made to search for dark matter candidate particles. Scalar field dark matter is one of the most prominent options that is being explored by the various precision experiments, such as gravitational-wave detectors, atomic clocks and gravity experiments. We describe a direct search for scalar field dark matter using the short-range gravity experiments, in which we investigate the possible influences of scalar field dark matter as a function of its mass. By analyzing the torque signals in the torsion pendulum experiments of the HUST-18 and HUST-20, we set new constraints on the large mass regions of scalar field dark matter parameter space. Based on the maximum reach analysis (MRA) method, the constraints on the photon coupling parameter $\Lambda_{\gamma}$ and electron coupling parameter $\Lambda_{\text{e}}$ improve on limits from previous direct searches in interferometer experiments by more than four orders of magnitude. Further combining the HUST-18 and HUST-20 experiments, we also present the exclusion limits that are not dependent on MRA approximation. This work paves the way for dark-matter search in future HUST experiments, and the projected constraints can be competitive with those limits produced by the MRA method.