Search for Long-Lived Parents of the Z Boson
  We present the results of a search for new particles with long lifetime that decay to a Z boson. A long-lived parent of the Z is predicted by several models in addition to being an experimentally clean channel. We vertex dimuons with invariant mass near the Z peak and study the decay length distribution. No evidence of a long-lived component is found, and cross-section limits are presented on a fourth generation quark model. 
Adam L. Scott, representing the CDF Collaboration