Search for long-lived particles decaying into electron or photon pairs with the D0 detector

Understand

In this Letter we report on a search for long-lived particles that decay into final states with two electrons or photons.

• Such long-lived particles arise in a variety of theoretical models, like hidden valleys and supersymmetry with gauge-mediated breaking.
• By precisely reconstructing the direction of the electromagnetic shower we are able to probe much longer lifetimes than previously explored.
• We see no evidence of the existence of such long-lived particles and interpret this search as a quasi model-independent limit on their production cross section, as well as a limit on a long-lived fourth generation quark.