Dilatonic dark matter and its experimental detection

Assuming that the dilaton is the dark matter of the Universe, we propose an experiment to detect the relic dilaton using the electromagnetic resonant cavity, based on the dilaton-photon conversion in strong electromagnetic background. We calculate the density of the relic dilaton, and estimate the dilaton mass for which the dilaton becomes the dark matter of the Universe. With this we calculate the dilaton detection power in the resonant cavity, and compare it with the axion detection power in a similar resonant cavity experiment.

Figure 1

The dilaton mass density $\rho (\mu )$ denoted by ${\rho }_d$ (with respect to the critical density ${\rho }_c$) versus the dilaton mass $\mu$, obtained with $g_1\simeq g_2\simeq 1$.

Figure 2

The allowed mass $\mu$ of dilaton (unshaded region), where we leave $\beta ={\alpha }_5/{\alpha }_g$ arbitrary. The shaded region marked by ($-$) is the excluded region, and the dotted line represents the mass of the heavy dilaton whose daughter particles overclose the Universe.