Signatures of gravity-mediated dark matter interaction in theories with large extra dimensions

Abstract

Dark matter particles that couple to the Standard Model only through gravity are usually regarded as inaccessible to laboratory detection. This expectation can change in theories with $n$ extra spatial dimensions, where gravity is enhanced at short distances and the potential scales as $1/r^{1+n}$. We reconsider the gravity-mediated dark matter (DM) interactions in Arkani-Hamed-Dimopoulos-Dvali (ADD) models with $n$ large extra dimensions. The cumulative exchange of the gravitational Kaluza-Klein (KK) modes leads to the effective strength of interactions with the Standard Model nucleons that scales as $m_p{m}_{\chi }{M}_{\ast }^{-4}$, where $m_{\chi }$ is the mass of DM and $M_{\ast }$ is the fundamental $4+n$ dimensional mass scale. We confront this interaction with sensitivity achieved in the large Xe-based underground direct detection experiments and derive bounds on the $\{m_{\chi },M_{\ast }\}$ parameter space that stretches all the way to $M_{\ast }\sim$ few TeV. We also address the indirect detection of scalar $\chi$ that can resonantly annihilate via the on-shell KK modes into the SM particles $W^{\pm },Z,h$. The annihilation cross section for the process scales as $⟨\sigma v⟩\sim m_{\chi }^n{M}_{\ast }^{-n-2}$, and stringent limits on the same parameter space can be derived from observations of high-energy galactic $\gamma$ rays.

Comments: 8 pages, 3 figures