The Heavy Photon Search Experiment: Searching for a Hidden Sector with Strongly-Interacting-Massive-Particles (SIMPS)

Dark Matter (DM) is one of the biggest fundamental mysteries of our universe, but the current Standard Model (SM) of particle physics fails to provide any viable candidates that can describe the DM abundance we observe today. This inability to account for roughly 85% of the mass in our Universe motivates searching for new physics beyond the SM (BSM). Some well-motivated BSM scenarios suggest that DM belongs to a Hidden Sector (HS) of particles that is secluded from SM forces, but that interacts indirectly with the SM through new force carriers. One of these scenarios that is particularly interesting is a HS of strongly-interacting-massive-particles (SIMPs). The QCD-like SU(3) symmetry gives rise to dark pions (π_D) and dark vector mesons (V_D) analogous to SM QCD, where π_D constitute DM. The U(1) light gauge boson role is assigned to the well-motivated heavy (or dark) photon A', which kinetically mixes with the SM photon with coupling strength ε. Under certain mass hierarchy and parameter constraints, the SIMP model achieves the correct thermal DM relic abundance for m_πD ~ 0.01 - 1 GeV and ε ~ 10^-6 - 10^-2. The Heavy Photon Search Experiment (HPS) at the Thomas Jefferson National Accelerator Facility (JLAB) can probe this model through the electro-production of heavy photons, which subsequently decay to a π_DV_D pair, where the V_D is long-lived, and decays through a virtual A' to a resonant e⁺e^- pair. In this presentation, I will describe the on-going search for displaced V_D decays in 1096.27 nb^-1 of data taken by HPS in 2016.