Dark matter annihilation to neutrinos

We review the annihilation of dark matter into neutrinos over a range of dark\nmatter masses from MeV$/c^2$ to ZeV$/c^2$. Thermally-produced models of dark\nmatter are expected to self-annihilate to standard model products. As no such\nsignal has yet been detected, we turn to neutrino detectors to constrain the\n``most invisible channel.'' We review the experimental techniques that are used\nto detect neutrinos, and revisit the expected contributions to the neutrino\nflux at current and upcoming neutrino experiments. We place updated constraints\non the dark matter self-annhilation cross section to neutrinos $\\langle \\sigma\nv \\rangle$ using the most recently available data, and forecast the sensitivity\nof upcoming experiments such as Hyper-Kamiokande, DUNE, and IceCube Gen-2.\nWhere possible, limits and projections are scaled to a single set of dark\nmatter halo parameters for consistent comparison. We consider Galactic and\nextragalactic signals of $s$, $p$, and $d$-wave annihilation processes directly\ninto neutrino pairs, yielding constraints that range from $\\langle \\sigma v\n\\rangle \\sim 2.5\\times10^{-26}~{\\rm cm}^3 {\\rm s}^{-1}$ at 30 MeV$/c^2$ to\n$10^{-17}~{\\rm cm}^3{\\rm s}^{-1}$ at 10$^{11}$ GeV$/c^2$. Experiments that\nreport directional and energy information of their events provide much stronger\nconstraints, outlining the importance of making such data public.\n