A method for identifying H -> tau tau -> e mu pTmiss at the CERN LHC

TL;DR

This work analyzes the identification of H→ττ→eμ/ pTmiss in weak-boson fusion at the LHC for $M_H$ in the $100-150$ GeV range, using forward tagging jets, lepton isolation, tau-pair mass reconstruction, and a central minijet veto to suppress backgrounds. A parton-level Monte Carlo with full tree-level matrix elements and detector smearing demonstrates that a clean signal can be observed with about $60~\mathrm{fb}^{-1}$ in most of this mass range, and a No-Lose Theorem shows MSSM coverage with as little as $40~\mathrm{fb}^{-1}$. The study highlights a robust channel for measuring the Higgs-fermion coupling and for probing MSSM Higgs sectors, with potential calibration via $Zjj$ processes for minijet-veto efficiencies. Overall, weak-boson fusion provides a low-background, high-signal-channel for Higgs physics at the LHC.

Abstract

Weak boson fusion promises to be a copious source of intermediate mass Higgs bosons at the LHC. The additional very energetic forward jets in these events provide for powerful background suppression tools. We analyze the subsequent H -> tau tau -> e mu pTmiss decay for Higgs boson masses in the 100-150 GeV range. A parton level analysis of the dominant backgrounds demonstrates that this channel allows the observation of H -> tau tau in a low-background environment, yielding a significant Higgs boson signal with an integrated luminosity of order 60 fb^-1 or less, over most of the mass range. We also restate a No-Lose Theorem for observation of at least one of the CP-even neutral Higgs bosons in the MSSM, which requires an integrated luminosity of only 40 fb^-1.

Figures (10)

• Figure 1: Upper: Normalized $/\!\!\!p_T$ distribution for the signal (red) and various backgrounds: $t\bar{t} + jets$ (solid blue), $b\bar{b}jj$ (dashed blue), QCD $WWjj$ (solid green), EW $WWjj$ (dashed green), QCD $\tau\tau jj$ (solid magenta) and EW $\tau\tau jj$ (dashed magenta). The cuts of Eqs. (\ref{['eq:basic']})-(\ref{['eq:bveto']}) are imposed. Lower: The same for the normalized $p_T$ distribution of the reconstructed Higgs boson, except that QCD and EW $WWjj$ contributions have been combined (solid green).
• Figure 2: Normalized invariant mass distribution of the two tagging jets for the signal and the various backgrounds as in Fig. \ref{['fig:ptmiss']}. The cuts of Eqs. (\ref{['eq:basic']})-(\ref{['eq:bveto']}) are imposed. (The distributions are essentially unchanged after imposing the additional cut of Eq. \ref{['eq:ptmiss']}.)
• Figure 3: Scatter plots of $x_{\tau_1}$ v. $x_{\tau_2}$ with the cuts of Eqs.(\ref{['eq:basic']})-(\ref{['eq:cosphi']}), for the 120 GeV $Hjj$ signal, $b\bar{b}jj$, $WWjj$ and $t\bar{t} + jets$ reducible backgrounds. The number of points in each plot is arbitrary and corresponds to significantly higher integrated luminosities than expected for the LHC. The solid lines indicate the cuts of Eq. (\ref{['eq:xtau']}).
• Figure 4: Reconstructed tau-pair mass distribution for $WWjj$ and $t\bar{t}+jets$ events (solid blue), $b\bar{b}jj$ events (dashed blue) and QCD+EW $Zjj$ events (magenta). The combined curves are also shown (black). The cuts of Eqs. (\ref{['eq:basic']})-(\ref{['eq:cosphi']}) are imposed.
• Figure 5: Normalized angular distributions of the charged leptons: a) azimuthal opening angle and b) separation in the lego plot. Results are shown for Higgs boson masses of 100 and 150 GeV (solid and dashed red lines, respectively) and for the various backgrounds: $t\bar{t} + jets$ (solid blue), $b\bar{b}jj$ (dashed blue), combined QCD and EW $WWjj$ (solid green), QCD $\tau\tau jj$ (solid magenta) and EW $\tau\tau jj$ (dashed magenta). The cuts of Eqs. (\ref{['eq:basic']})-(\ref{['eq:xtau']}),(\ref{['eq:taumass']}) are imposed.