Superheavy WIMP dark matter from incomplete thermalization

TL;DR

This paper explores the viability of superheavy WIMP dark matter with vector Z-boson coupling, showing it can match observed dark matter abundance if reheating temperature is appropriately tuned, despite null results in direct detection.

Contribution

It demonstrates that superheavy WIMP dark matter can account for observed abundance under specific reheating conditions, challenging previous assumptions about direct detection constraints.

Findings

Superheavy WIMPs with mass > 10^9 GeV remain viable dark matter candidates.

Reheating temperature around one thirtieth of the WIMP mass reproduces observed abundance.

Direct inflaton decay into dark matter is negligible or forbidden in the model.

Abstract

Although it is usually thought that a class of weakly interacting massive particle (WIMP) dark matters (DMs), which have the vector coupling with the $Z$ boson, is denied by null results of the direct DM searches, such WIMP DMs are still viable if they are superheavy with the mass of $m_{DM} \gtrsim 10^9$ GeV. In the future, the superheavy WIMP DMs can be searched up to $m_{DM} \simeq 10^{12}$ GeV, which corresponds to the so-called neutrino floor limit. We show that the observed abundance of $\Omega_\mathrm{DM}h^2 \simeq 0.1$ for a superheavy WIMP DM can be reproduced by a suitable reheating temperature of $T_R \simeq m_{DM}/29$ after inflation, if the direct inflaton decay into DM is negligible or kinematically forbidden.