Cosmological production of dark nuclei

Abstract

We study the formation of Dark Matter nuclei in scenarios where DM particles are baryons of a new confining gauge force. The dark nucleosynthesis is analogous to the formation of light elements in the SM and requires as a first step the formation of dark deuterium. We compute this process from first principles, using the formalism of pion-less effective theory for nucleon-nucleon interactions. This controlled effective field theory expansion allows us to systematically compute the cross sections for generic SM representations under the assumption of shallow bound states. In the context of vector-like confinement models we find that, for nucleon masses in the TeV range, baryonic DM made of electro-weak constituents can form a significant fraction of dark deuterium and a much smaller fraction of dark tritium. Formation of dark nuclei can also lead to monochromatic photon lines in indirect detection. Models with singlets do not undergo nucleosynthesis unless a dark photon is added to the theory.

Tev-scale thermal WIMPs: Unitarity and its consequences

“…In the case of heavy, multi-TeV DM, the low number density makes hydrogen-like recombination very inefficient [81]. Thus if heavy DM is an atom, it is formed by a non-abelian confining gauge force.…”

Indirect detection of composite asymmetric dark matter

“…[15]. The cross section for the formation of an s-wave bound state through a magnetic transition reads [10]…”

“…(2) allow for s-wave transitions in isospin channels 1 0 ↔ 3 1 and 3 1 ↔ 5 0 . Cosmological production of bound states being typically small for DM masses in the TeV range [10], we will take DM today to be composed entirely of neutral nucleons, V 0 . The antisymmetry of its wave function implies that an s-wave initial state must have spin 0.…”

“…The gray (red) region is the exclusion due to γ-ray lines from FERMI [19] (HESS [20]) in our Galactic Center. subsequently decay to the ground state through a magnetic transition with rate Γ ∼ κ 2 α ffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi [10], leading to a second monochromatic photon signal with energy E γ ¼ E B 1 − E B 3 . Multiple photon lines with equal rate would be a smoking gun signature for boundstate formation in the dark sector, allowing us to easily discriminate it from signals due to DM annihilation.…”

“…The cosmological production of dark nuclei was studied in [10]; here we consider observational implications. At DM velocities relevant for indirect detection, dark deuterium is produced essentially at rest through emission of a quantum of energy E B .…”