Heavy Higgsino Dark Matter With Low Reheating in View of the LZ High-Recoil Event

Abstract

We show that a heavy higgsino $\tilde h$ with mass $m_{\tilde h}\sim0.1~{\rm PeV}$, which can be made consistent with the recent LUX-ZEPLIN event avoiding constraints from direct and indirect detection, can account for the present cold dark matter abundance of the universe, if the reheating temperature is bounded as $T_{\rm rh}\lesssim 595~{\rm GeV}$. These values can be achieved by a possible out-of-equilibrium decay of a modulus $ϕ$ with mass $m_ϕ\gg m_{\tilde h}$ and a non-vanishing branching ratio into $\tilde h$'s which plays a decisive role in reducing $T_{\rm rh}$ below its upper limit via the non-thermal $\tilde h$ production. The modulus $ϕ$ can be identified with the scalar component of the goldstino superfield which is involved in the generation of the $μ$ parameter of MSSM (with $μ\simeq m_{\tilde h}$) via the Giudice-Masiero mechanism.