A Novel Technique to Reconstruct the Z mass in WZ/ZZ Events with Lepton(s), Missing Transverse Energy and Three Jets at CDFII

Observing WZ/ZZ production at the Tevatron in a final state with a lepton, missing transverse energy and jets is extremely difficult because of the low signal rate and the huge background. In an attempt to increase the acceptance we study the sample where three high-energy jets are reconstructed, where about 1/3 of the diboson signal events are expected to end. Rather than choosing the two ET-leading jets to detect a Z signal, we make use of the information carried by all jets. To qualify the potential of our method, we estimate the probability of observing an inclusive diboson signal at the three standard deviations level (P3σ) to be about four times larger than when using the two leading jets only. Aiming at applying the method to the search for the exclusive WZ/ZZ → (ell)νq(bar q) channel in the three jets sample, we analyzed separately the sample with at least one b-tagged jet and the sample with no tags. In WZ/ZZ → (ell)νb(bar b) search, we observe a modest improvement in sensitivity over the option of building the Z-mass from the two leading jets in ET. Studies for improving the method further are on-going.