Inclusive Search for Anomalous Production of High-$p_T$ Like-Sign Lepton Pairs in $p\overline{p}$ Collisions at $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with $p_T>11\mathrm{G}\mathrm{e}\mathrm{V}/c$ using a $107\mathrm{p}{\mathrm{b}}^{\mathrm{-}\mathrm{1}}$ sample of 1.8 TeV $p\overline{p}$ collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of ${0.63}_{-0.07}^{+0.84}$ events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity ($\tan \beta =3$) model.

Figure 1

(a)  and (b)  show the energy in the $IS{O}_{\Delta R=0.4}$ cone for electrons and muons, respectively, in the $Z$ dilepton data set (points) and jet background data set (histogram). Errors shown are statistical only. (c)  and (d)  show $ϵ$ for electrons and muons, respectively, as a function of jet background $ϵ$ for original $ISO$ (solid line) and new $ISO$ (dashed line). The markers indicate the position of the nominal original and new $ISO$ cuts on the $ϵ$ curves.

Figure 2

Observed events in kinematical regions adjacent to the signal region; see Table 1.

Figure 3

The 95% confidence level limit on the cross section for “$WZ$-like” production as a function of the $W$-like particle mass, for two representative masses of the $Z$-like particle.

Figure 4

The 95% confidence level limit on the parameters $m_0$ and $m_{1/2}$ in the mSUGRA framework for $\tan \beta =3$, $\mu <0$, and $A_0=0$ (hatched region). The shaded region is theoretically excluded. The dip near $75\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ results from the loss of sensitivity to the ${\tilde{\chi }}_1^{\pm }{\tilde{\chi }}_2^0$ signal due to decays of ${\tilde{\chi }}_1^{\pm }$ and ${\tilde{\chi }}_2^0$ to sneutrinos. At lower $m_0$, the limit is regained due to sensitivity to $\tilde{q}$ and $\tilde{g}$ production [20].