Search for Heavy Long-Lived Particles that Decay to Photons at CDF II

We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of γ+jet+missing transverse energy events in pp̄ collisions at √s=1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb^-1 of collision data, we observe 2 events, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with χ₁⁰→γG and place the world-best 95% C.L. lower limit on the χ₁⁰ mass of 101 GeV/c² at τ_χ₁⁰=5 ns.