Four Taus at the Tevatron

TL;DR

The paper addresses nonstandard Higgs decays in extended Higgs sectors, focusing on a light electroweak axion $a^0$ that mediates $h^0\to a^0 a^0\to 4\tau$ decays. Using NMSSM couplings and current limits, the authors assess the Tevatron's ability to observe these signals via gluon-gluon fusion and associated production, with $6$ fb$^{-1}$ of data and $m_h$ around $100$--$110$ GeV. They estimate lepton efficiencies, propose discriminants like a "quiet" event variable to suppress heavy-flavor backgrounds, and discuss multiple channels including tri-leptons and $e\mu$ topologies. The results indicate possible excesses in several channels, motivating targeted searches at the Tevatron and informing LHC search strategies for tau-rich Higgs decays.

Abstract

We study extensions of the Standard Model where the Higgs boson dominantly decays via a cascade to four tau leptons, and discuss whether this decay is visible at the Tevatron. We find that with an integrated luminosity of 6 fb^-1, there can be excesses in multi-lepton events in several channels for a Higgs boson of a mass = 110 GeV.

Figures (4)

• Figure 1: The $p_T$ distribution of the leptons in tri-lepton events coming from $h^0\rightarrow a^0a^0\rightarrow 4\tau$. We have imposed cuts of $\eta_\ell < 2.0$, and $p_{T}^{\ell} > 3.0$ GeV, as well as rudimentary isolation cuts as described in the text.
• Figure 2: The $\Delta R \equiv \sqrt{ \Delta \phi^{2} + \Delta \eta ^{2}}$ of the e-$\mu$ pair. Note that a substantial portion of the signal lies in the region $\Delta R < 0.4$, which might be eliminated by a naive isolation cut. The opening angle is controlled by the ratio $m_a/m_{h}$. Here, $m_{h}=100$ GeV and $m_{a^{0}}$=8 GeV.
• Figure 3: The $p_T$ distribution of the close e-$\mu$ pair. Events are selected where there is a e-$\mu$ pair with a $\Delta R < 1.0$.
• Figure 4: One possible discriminant between opposite flavor, opposite charge di-lepton events and $j \tau\tau$ events. The discrimant, $M$, described in the text versus $\Delta \phi_{e\mu}$. Notice that the four tau opposite flavor events are clustered at small $M$ close to $\Delta \phi_{e\mu} =0, \pi$ whereas the jet di-tau events have much higher $M$'s, thus providing a clean discriminant between the two types of events.