Search for New Physics in High $p_T$ Like-Sign Dilepton Events at CDF II

We present a search for new physics in events with two high $p_T$ leptons of the same electric charge, using data with an integrated luminosity of $6.1{\mathrm{fb}}^{-1}$. The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly charged scalars decaying to like-sign dileptons, $m_{H^{\pm \pm }}>190–245\mathrm{GeV}/c^2$, assuming 100% BR to $ee$, $\mu \mu$ or $e\mu$.

Figure 1

Distribution of jet multiplicity, missing transverse momentum, leading lepton $p_T$, and subleading lepton $p_T$ in observed like-sign dilepton events and expected backgrounds. The $VV$ contribution includes $WW$, $WZ$, $ZZ$, and $W\gamma$.

Figure 2

The observed and expected standard model spectra in the $ee$, $\mu \mu$, and $e\mu$ channels. The doubly charged Higgs boson signal is shown for a range of masses. The $VV$ contribution includes $WW$, $WZ$, $ZZ$, and $W\gamma$.

Figure 3

Observed upper limits at 95% C.L. on the production cross section for a doubly charged Higgs boson times the branching fraction to $ee$, $\mu \mu$ or $e\mu$ exclusively, compared to results from D0 [9]. Also shown are next-to-leading-order theoretical calculations of the cross section, assuming the Higgs boson is a member of a singlet, doublet, or triplet.