Resonant Production of Vector DM States Characterized by Monophoton ISR at High-Energy Colliders

Dark matter research, aimed at unraveling astrophysical enigmas, faces the challenge of lacking concrete evidence connecting dark matter with the observable universe in both experimental and theoretical particle physics. Our study investigates a simplified extension to the Standard Model (SM) where SM fermion interacts with a hypothetical vector dark matter (DM) particle in high-energy collisions, mediated by a proposed massive spin-1 particle, \(Z^{\prime }\) $Z^{\prime }$ . We specifically explore vector DM pair production through fermion annihilation in this mediator, focusing on a near-resonance condition ( \(m_{\chi }\sim M_{Z^{\prime }}/2\) $m_{\chi }\sim M_{Z^{\prime }}/2$ ). This includes examining monophoton production, a SM signal, as a result of initial-state radiation. We also calibrate the coupling constants between DM and SM particles relative to Planck satellite thermal relic density data, particularly near a resonance where traditional models anticipate more relic density suppression. Our findings, consistent with expected relic density at resonance regimes, suggest mass ranges and coupling constants for these DM particles that align with collider and astrophysical limits, to be validated in CLIC and LHC settings.