Theory and Phenomenology of Planckian Interacting Massive Particles as
  Dark Matter
  Planckian Interacting Dark Matter (PIDM) is a minimal scenario of dark matter
assuming only gravitational interactions with the standard model and with only
one free parameter, the PIDM mass. PIDM can be successfully produced by
gravitational scattering in the thermal plasma of the Standard Model sector
after inflation in the PIDM mass range from TeV up to the GUT scale, if the
reheating temperature is sufficiently high. The minimal assumption of a GUT
scale PIDM mass can be tested in the future by measurements of the primordial
tensor-to-scalar ratio. While large primordial tensor modes would be in tension
with the QCD axion as dark matter in a large mass range, it would favour the
PIDM as a minimal alternative to WIMPs. Here we generalise the previously
studied scalar PIDM scenario to the case of fermion, vector and tensor PIDM
scenarios, and show that the phenomenology is nearly identical, independent of
the spin of the PIDM. We also consider the specific realisation of the PIDM as
the Kaluza Klein excitation of the graviton in orbifold compactifications of
string theory, as well as in models of monodromy inflation and in Higgs
inflation. Finally we discuss the possibility of indirect detection of PIDM
through non-perturbative decay.
