Search for New Dielectron Resonances and Randall-Sundrum Gravitons at the Collider Detector at Fermilab

A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of $5.7{\mathrm{fb}}^{-1}$ is presented. No significant excess over the expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed ($960\mathrm{GeV}/c^2$) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the $5.4{\mathrm{fb}}^{-1}$ diphoton analysis, the RS-graviton lower-mass limit for the coupling $k/{\overline{M}}_{\mathrm{Pl}}=0.1$ is $1058\mathrm{GeV}/c^2$, making it the strongest limit to date.

Figure 1

(a) The dielectron-mass distribution for the SM background (stacked histograms of DY, QCD, diboson, and $t\overline{t}$) and the CDF data. The QCD background is derived from CDF data. The electroweak backgrounds are estimated using MC normalized to the data luminosity times theoretical cross sections, without fitting to any part of the dielectron data distribution. (b) The dielectron-mass distribution between 200 and $600\mathrm{GeV}/c^2$.

Figure 2

The $p$ value as a function of the dielectron mass. The $1\mathrm{\text{−}}\sigma$ range of expected minimum $p$ value seen at any bin is shown.

Figure 3

(a) The 95% C.L. upper limit on the lightest RS-graviton production cross section from the dielectron analysis, as a function of the graviton’s mass. (b) The respective cross section and mass limits for the combination of the dielectron and diphoton analyses.

Figure 4

The area excluded in the $k/{\overline{M}}_{\mathrm{Pl}}$ vs $m_1$ RS-model parameter space by the $5.7{\mathrm{fb}}^{-1}$ dielectron analysis (area above long-dashed line), the $5.4{\mathrm{fb}}^{-1}$ diphoton analysis (area above short-dashed line), and their combination (area above solid line).