Search for Doubly Charged Higgs Bosons with Lepton-Flavor-Violating Decays Involving $\tau$ Leptons

We search for pair production of doubly charged Higgs particles ($H^{\pm \pm }$) followed by decays into electron-tau ($e\tau$) and muon-tau ($\mu \tau$) pairs using data ($350{\mathrm{pb}}^{-1}$) collected from $\overline{p}p$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ by the CDF II experiment. We search separately for cases where three or four final-state leptons are detected, and combine results for exclusive decays to left-handed $e\tau$ ($\mu \tau$) pairs. We set an $H^{\pm \pm }$ lower mass limit of $114(112)\mathrm{GeV}/c^2$ at the 95% confidence level.

Figure 1

Theoretical production cross sections for the pair production of left-handed $H^{\pm \pm }$, and 95% C.L. limit curves for $\sigma (p\overline{p}\to H^{++}{H}^{--}\to )\times B^2({\ell }^{+}{\tau }^{+}{\ell }^{-}{\tau }^{-})$, for $I=e$ (solid), $\mu$ (dashed). The vertical dashed line corresponds to limits from experiments at LEP2 for exclusive $H_L^{\pm \pm }$ decays to any one dilepton channel [9].