Search for the Higgs boson in lepton, tau, and jets final states

We present a search for the standard model Higgs boson in final states with an electron or muon and a hadronically decaying tau lepton in association with two or more jets using $9.7{\mathrm{fb}}^{-1}$ of Run II Fermilab Tevatron Collider data collected with the D0 detector. The analysis is sensitive to Higgs boson production via gluon fusion, associated vector boson production, and vector boson fusion, followed by the Higgs boson decay to tau lepton pairs or to $W$ boson pairs. The ratios of 95% C.L. upper limits on the cross section times branching ratio to those predicted by the standard model are obtained for orthogonal subsamples that are enriched in either $H\to \tau \tau$ decays or $H\to WW$ decays, and for the combination of these subsample limits. The observed and expected limit ratios for the combined subsamples at a Higgs boson mass of 125 GeV are 11.3 and 9.0, respectively.

Figure 1

The ${\mathrm{NN}}_{\tau }$ distribution for (a) type 1 taus, (b) type 2 taus, (c) type 3 taus, using data taken from a sample of $Z\to \tau \tau$ events with no requirements on the number of associated jets, and (d) the ${\mathrm{NN}}_{\tau /e}$ distribution for tau type 2 from a sample of $e\tau jj$ events.

Figure 2

Input variables for the $\mu \tau jj$ BDT training, (a) $\Delta \eta (j_1,j_2)$, (b) $M(j1j2)$, (c) $M(\tau \tau )$, and for the $e\tau jj$ BDT training, (d) $p_T(j_1)$, (e) $M_T({\mathrm{E̸}}_T,\ell \tau )$, (f) $N_{\mathrm{soln}}(\tau \tau )$.

Figure 3

${\mathrm{BDT}}_{\mathrm{TW}}$ outputs from the training of $H\to \tau \tau$ vs. $H\to WW$ for (a) the $\mu \tau jj$ analysis and (b) the $e\tau jj$ analysis. The solid (dashed) lines show the sum of all production processes with $H\to \tau \tau$ ($H\to WW$) decays at $M_H=125\mathrm{GeV}$. Events near ${\mathrm{BDT}}_{\mathrm{TW}}=-1$ are dominantly $H\to WW$ and those near $+1$ are mainly $H\to \tau \tau$.

Figure 4

Final discriminant distributions for the $\mu \tau jj$ analysis for (a) the T subsample at $M_H=125\mathrm{GeV}$ and (b) the W subsample at $M_H=145\mathrm{GeV}$.

Figure 5

Final discriminant distributions for the $e\tau jj$ analysis for (a) the T subsample at $M_H=125\mathrm{GeV}$ and (b) the W subsample at $M_H=145\mathrm{GeV}$.

Figure 6

LLR distributions for (a) the T subsample, (b) the W subsample, and (c) the sum of the combined T and W subsamples. The $\mu \tau jj$ and $e\tau jj$ analyses are combined. The black dashed line shows the expected LLR for the background-only hypothesis and the red dash-dotted line shows the expected LLR for the signal-plus-background hypothesis. The solid black line indicates the observed LLR. The green (yellow) shaded bands indicate the $\pm 1\mathrm{s}.\mathrm{d}.$ ($\pm 2\mathrm{s}.\mathrm{d}.$) uncertainties on the expected background-only LLR.

Figure 7

The ratio of 95% C.L. upper limits on Higgs boson production for the (a) T subsample, (b) W subsample, and (c) the sum of the T and W subsamples. The $\mu \tau jj$ and $e\tau jj$ analyses are combined. The green (yellow) shaded bands indicate the $\pm 1\mathrm{s}.\mathrm{d}.$ ($\pm 2\mathrm{s}.\mathrm{d}.$) uncertainties on the expected limit ratios.