title: Hypercharged dark matter and direct detection as a probe of reheating.
abstract: The lack of new physics at the LHC so far weakens the argument for TeV scale thermal dark matter. On the other hand, heavier, nonthermal dark matter is generally difficult to test experimentally. Here we consider the interesting and generic case of hypercharged dark matter, which can allow for heavy dark matter masses without spoiling testability. Planned direct detection experiments will be able to see a signal for masses up to an incredible 1010  GeV, and this can further serve to probe the reheating temperature up to about 109  GeV, as determined by the nonthermal dark matter relic abundance. The Z-mediated nature of the dark matter scattering may be determined in principle by comparing scattering rates on different detector nuclei, which in turn can reveal the dark matter mass. We will discuss the extent to which future experiments may be able to make such a determination.
authors.affiliation: Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom and Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8568, Japan.
authors.forename: Brian
authors.initials: B
authors.lastname: Feldstein
authors.affiliation: Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8568, Japan and ICRR, University of Tokyo, Kashiwa 277-8582, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ibe
authors.affiliation: Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8568, Japan.
authors.forename: Tsutomu T
authors.initials: TT
authors.lastname: Yanagida