Joint collider and direct-detection reach for a B−L portal consistent with WIMP baryogenesis

Determine whether there exists parameter space in a gauged U(1)_{B−L} portal—specified by the mediator mass M_{\hat{Z}} and coupling g_{B−L}—that simultaneously yields observable dark-matter direct-detection signals near the neutrino floor and an observable collider portal to the dark sector, while preserving the baryon-parent χ WIMP freezeout required for WIMP baryogenesis.

Background

The authors consider a massive abelian U(1)_{B−L} gauge boson \hat{Z} that couples to both visible and dark sectors and can mediate dark-matter nuclear scattering and collider production of dark states. They present benchmarks showing either near-current direct-detection sensitivity with weak coupling and light \hat{Z}, or potential collider accessibility with heavy \hat{Z} and stronger coupling—each with trade-offs.

However, ensuring that \hat{Z}-mediated interactions do not spoil the χ freezeout dynamics that underpin WIMP baryogenesis constrains the portal. The authors could not find parameter points achieving both goals simultaneously within their minimal setup, suggesting the need to explore alternative WIMP baryogenesis regimes or extended model-building to resolve this tension.