Symmetron Dark Energy in Laboratory Experiments

The symmetron scalar field is a matter-coupled dark energy candidate which effectively decouples from matter in high-density regions through a symmetry restoration. We consider a previously unexplored regime, in which the vacuum mass $\mu \sim 2.4\times {10}^{-3}\mathrm{eV}$ of the symmetron is near the dark energy scale, and the matter coupling parameter $M\sim 1\mathrm{TeV}$ is just beyond standard model energies. Such a field will give rise to a fifth force at submillimeter distances which can be probed by short-range gravity experiments. We show that a torsion pendulum experiment such as Eöt-Wash can exclude symmetrons in this regime for all self-couplings $\lambda \lesssim 7.5$.

Figure 1

Estimated torque in the apparatus of [19] for several symmetron models. $\lambda =1$ for all models shown; $M=500\mathrm{GeV}$ for $\mu ={10}^{-2}\mathrm{eV}$ and $M=1\mathrm{TeV}$ otherwise.

Figure 2

Estimated constraints on symmetron dark energy. The light-green shaded region is excluded for $\mu =M_{\Lambda }=2.4\times {10}^{-3}\mathrm{eV}$, while models in the black shaded region are unscreened. The solid red, dashed blue, and dotted purple curves show lower bounds on $\lambda$ for $\mu ={10}^{-4}$, ${10}^{-3}$, and ${10}^{-2}\mathrm{eV}$, respectively.