Search for new heavy particles decaying toZ0Z0→eeeeinpp¯co

Abstract

We report the results of a search for the anomalous production of a massive particle decaying to four electrons via two Z 0 bosons in 1:1 fb À1 of p " p collisions at ffiffi ffi s p ¼ 1:96 TeV collected by the CDF II detector at Fermilab. We employ optimized electron identification criteria to maximize acceptance and efficiency. We estimate the backgrounds in the invariant mass range 500-1000 GeV=c 2 to be 0:028 AE 0:009ðstatÞ AE 0:011ðsystÞ events. We observe zero events in this search region. Assuming a Randall-Sundrum graviton production model, we set 95% C.L. limits on  BFðG ! Z 0 Z 0 Þ < 4-6 pb, depending on the graviton mass.

Search for New Heavy Particles Decaying to Z0 Z0 to llll, lljj in p pbar Collisions at Sqrt(s) = 1.96 TeV

“…20 shows the resultant limits along with the k/M P l = 0.1 Randall-Sundrum (RS1) graviton cross-section from herwig. The present search improves the O(4 pb) limit of the earlier eeee search [9] by an order of magnitude.…”

“…The electron criteria listed in Tables I through II are nearly identical to the previous eeee analysis [9]. The double Z boson mass peak signature admits little background, allowing appreciably more efficient electron criteria than those used for many other CDF analyses (for example, Ref.…”

“…In part because much of the data were collected with the CMUP trigger and during periods with measured cross-sections in good agreement with expectation, and because two of the six analysis channels do not involve muons, this systematic uncertainty over-covers the observed variation in cross section and is the dominant uncertainty for the analysis. Nevertheless, the final sensitivity of the analysis improves substantially on the earlier eeee search [9].…”

“…The LEP data place only indirect constraints on heavier, resonant ZZ diboson production [8], however, and direct production constraints at high ZZ diboson masses must be probed at hadron colliders. To the pre-viously published CDF search for four-electron production via X → ZZ → eeee with data corresponding to 1.1 fb −1 of integrated luminosity [9], we now add the dijet channels eejj and µµjj, which improve sensitivity at very high X masses where their background is negligible, and the four-electron or -muon channels eeµµ and µµµµ, which contribute sensitivity to new physics at intermediate masses where the Z + jet(s) backgrounds are larger.…”