Search For Nonpointing And Delayed Photons In The Diphoton And Missing Transverse Momentum Final State In 8 Tev Math Display

Search for Nonpointing and Delayed Photons in the Diphoton and Missing Transverse Momentum Final State in 8 TeV [math Display

We performed a search, using the full 20.3 fb1 data sample of 8 TeV proton-proton collisions collected in 2012 with the ATLAS detector at the LHC, for photons originating from a displaced vertex due to the decay of a neutral long-lived particle into a photon and an invisible particle. The analysis investigates the diphoton plus missing transverse momentum final state, and is therefore most sensitive to pair production of long-lived particles. The analysis technique exploits the capabilities of the ATLAS electromagnetic calorimeter to make precise measurements of the flight direction, as well as the time of flight, of photons. No excess is observed over the Standard Model predictions for background. Lastly, exclusion limits are set within the context of gauge mediated supersymmetry breaking models, with the lightest neutralino being the next-to-lightest supersymmetric particle and decaying into a photon and gravitino with a lifetime in the range from 250 ps to about 100 ns.

Search for Non-Pointing Photons in the Diphoton and Missing Transverse Energy Final State in 7 TeV Pp Collisions Using the ATLAS Detector

The gravitinos escape the detector, giving rise to missing energy, while the photons can appear not to originate from the primary vertex of the event, and are measured with a delay with respect to the collision time. No excess was observed above the background expected from Standard Model processes. The results were used to set exclusion limits at 95% CL in the two-dimensional parameter space defined by the supersymmetry breaking scale and the lifetime of the lightest neutralino.

Search for Non-prompt Photons in a Diphoton and Large Missing Transverse Momentum Final State at the ATLAS Detector