Search for Higgs Bosons Predicted in Two-Higgs-Doublet Models via Decays to Tau Lepton Pairs in 1.96 TeV $p\overline{p}$ Collisions

We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using $1.8{\mathrm{fb}}^{-1}$ of integrated luminosity of $p\overline{p}$ collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of $\tan \beta$ versus $m_A$ (the ratio of the vacuum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).

Figure 1

Observed and predicted distributions of $m_{\mathrm{vis}}$ for the $e+\tau$ and $\mu +\tau$ channels (a) and $e+\mu$ channel (b). The predicted signal distribution (for $\varphi =h/A/H$) corresponds to that for the $m_A=140\mathrm{GeV}/c^2$ signal assuming a value of the cross section excluded at 95% C.L. Note that in each plot the last bin is an overflow bin. Here “Other EW” refers to all SM backgrounds other than $Z/{\gamma }^{*}\to \tau \tau$ and background arising from $\mathrm{\text{jet}}\to \tau$ misidentification.

Figure 2

Observed 95% C.L. upper limits on the cross section for $\varphi =h/A/H$ production as a function of $m_A$. The grey bands show the median expected limit under the null hypothesis, and indicate the $\pm 1$- and $\pm 2$-standard-deviation ranges.

Figure 3

Regions in the MSSM plane of $\tan \beta$ versus $m_A$ excluded at 95% C.L. assuming heavy ($\sim 1\mathrm{TeV}/c^2$) sfermions. The top panel shows excluded regions for Higgsino mass parameter $\mu >0$, and the bottom panel shows excluded regions for $\mu <0$. Each panel shows the slightly different excluded regions for two scalar top mixing scenarios. The solid and dashed curves show the previously published bounds [8].