Constraining the Symmetron Model with the HUST-2020 Torsion Pendulum Experiment

The search for dynamically screening the coupling between the scalar field and matter in high-density environment is achievable with the symmetron model. The high-accuracy and short-range gravity experiment is proposed to test the symmetron model. In this Letter, the data of the HUST-2020 torsion pendulum experiment testing the inverse-square law at submillimeter range is analyzed to constrain the symmetron model. The results show that the HUST-2020 experiment is uniquely sensitive to probe the symmetron model with a mass scale of $\mu =7.2\times {10}^{-3}\mathrm{eV}$, and the self-coupling parameter $\lambda \lesssim 105$ is excluded at mass scale $M=0.3\mathrm{TeV}$. Especially, at the dark energy scale $\mu =2.4\times {10}^{-3}\mathrm{eV}$, the constraint at $M=1.3\mathrm{TeV}$ is improved by about 10 times the previous constraints on the torsion pendulum experiment.

Figure 1

Diagram of the HUST-2020 torsion pendulum experiment [31].

Figure 2

Sketch of symmetron field profiles for the two-plate model (a) and the three-plate model (b). The densities of the tungsten, glass, foil, and vacuum regions are expressed as ${\rho }_w$, ${\rho }_b$, ${\rho }_s$, and ${\rho }_v$, respectively.

Figure 3

The influence of the foil on symmetron torque difference. The dots and lines represent the results of numerical and semianalytical calculations, respectively. Here, the self-coupling $\lambda =1$, and $m_0^2={\rho }_s/M^2-{\mu }^2$.

Figure 4

The constraint of the torsion pendulum experiment on symmetron model. For the HUST-2020 experiment, the yellow and green regions are excluded, respectively, for $\mu =7.2\times {10}^{-3}\mathrm{eV}$ and $\mu =2.4\times {10}^{-3}\mathrm{eV}$; a combination of the blue (solid) and purple (both solid and dashed) curves gives lower bounds on $\lambda$ for $\mu =4.8\times {10}^{-3}\mathrm{eV}$. The gray shaded region surrounded by black curve is excluded for $\mu =2.4\times {10}^{-3}\mathrm{eV}$ by Eöt-Wash experiment [30].