Brane-World Dark Matter

We show that, in the context of brane-world scenarios with low tension $\tau =f^4$, massive brane fluctuations (branons) are natural dark matter candidates. We calculate the present abundances for both hot (warm) and cold branons in terms of the branon mass $M$ and the tension scale $f$. The results are compared with the current experimental bounds on these parameters. We also study the prospects for their detection in direct search experiments and comment on their characteristic signals in the indirect ones.

Figure 1

Relic abundance for a model with one branon $N=1$. The line on the left is the ${\Omega }_{Br}{h}^2=0.129-0.095$ curve for hot-warm relics. The line on the right corresponds to cold relics. The lower striped area is the estimated excluded region by single-photon processes at CERN $e^{+}{e}^{-}$ collider LEP-II [9] and the upper area is also excluded by branon overproduction.

Figure 2

Elastic branon-nucleon cross section ${\sigma }_n$ in terms of the branon mass. The two thick lines correspond to the ${\Omega }_{Br}{h}^2=0.129-0.095$ curve for cold branons in Fig. 1 with $N=1$ (left) and $N=7$ (right). The shaded areas on the left are the previous LEP-II exclusion regions [9], also for $N=1,7$. The solid lines correspond to the current limits on the spin-independent cross section from direct detection experiments: ZEPLIN1 [14], DAMA [15], and EDELWEISS [16]. The discontinuous lines are the projected limits for CRESST [17], GEDEON [18], CDMS [19], ZEPLIN4 [20], and GENIUS [21] (limits obtained from 22).