Closing in on mass-degenerate dark matter scenarios with antiprotons and
  direct detection
  Over the last years both cosmic-ray antiproton measurements and direct dark
matter searches have proved particularly effective in constraining the nature
of dark matter candidates. The present work focusses on these two types of
constraints in a minimal framework which features a Majorana fermion as the
dark matter particle and a scalar that mediates the coupling to quarks.
Considering a wide range of coupling schemes, we derive antiproton and direct
detection constraints using the latest data and paying close attention to
astrophysical and nuclear uncertainties. Both signals are strongly enhanced in
the presence of degenerate dark matter and scalar masses, but we show that the
effect is especially dramatic in direct detection. Accordingly, the latest
direct detection limits take the lead over antiprotons. We find that antiproton
and direct detection data set stringent lower limits on the mass splitting,
reaching 19% at a 300 GeV dark matter mass for a unity coupling. Interestingly,
these limits are orthogonal to ongoing collider searches at the Large Hadron
Collider, making it feasible to close in on degenerate dark matter scenarios
within the next years.
