A testable scenario of WIMPZILLA with Dark Radiation

Understand

As the electromagnetic gauge symmetry makes the electron stable, a new abelian gauge symmetry may be responsible for the stability of superheavy dark matter.

• The gauge boson associated with the new gauge symmetry naturally plays the role of dark radiation and contributes to the effective number of `neutrino species', which has been recently measured by Planck.
• We estimate the contribution of dark radiation from the radiative decay of a scalar particle induced by the WIMPZILLA in the loop.
• The scalar particle may affect the invisible decay of the Higgs boson by the Higgs portal type coupling.