Signatures of large composite Dark Matter states

Edward Hardy, Robert Lasenby, John March-Russell, Stephen M. West

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We investigate the interactions of large composite dark matter (DM) states with the Standard Model sector. Elastic scattering with SM nuclei can be coherently enhanced by factors as large as A squared, where A is the number of constituents in the composite state. This enhancement, for a given direct detection event rate, weakens the expected signals at colliders by up to 1/A. Moreover, the spatially extended nature of the DM states leads to an additional, characteristic, form factor modifying the momentum dependence of scattering processes, altering the recoil energy spectra in direct detection experiments. In particular, energy recoil spectra with peaks and troughs are possible, and such features could be confirmed with only O(50) events, independently of the assumed halo velocity distribution. Large composite states also generically give rise to low-energy collective excitations potentially relevant to direct detection and indirect detection phenomenology. We compute the form factor for a generic class of such excitations—quantised surface modes—finding that they can lead to coherently-enhanced, but generally sub-dominant, inelastic scattering in direct detection experiments. Finally, we study the modifications to capture rates in astrophysical objects that follow from the elastic form factor, as well as the effects of inelastic interactions between DM states once captured. We argue that inelastic interactions may lead to the DM collapsing to a dense configuration at the centre of the object.
Original languageEnglish
Number of pages31
JournalJournal of High Energy Physics
Issue number133
Early online date24 Jul 2015
Publication statusPublished - Jul 2015


  • Beyond Standard Model
  • Cosmology of Theories beyond the SM

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