Search for a Higgs boson multiplet in the lepton+jets channel at CDF

A. Truong1, A. Johnstone1, K. Rao1, D. Whiteson1, N. Goldschmidt2, J. Adelman3

1 University of California, Irvine
2 Florida, SLAC
3 Yale



for the CDF Collaboration

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Abstract


We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson ($H^0$), a lighter charged Higgs boson ($H^\pm$), and an even-lighter Higgs boson $h^0$, with decays leading to a $W$-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ collected by the CDF II detector in proton-antiproton collisions at $\sqrt{s}=1.96$ TeV. We find the data to be consistent with standard model predictions and report the results in terms of a simplified Higgs-cascade-decay model, setting 95\% confidence level upper limits on the product of cross-section and branching fraction from 1.3 pb to 15 fb as a function of $H^0$ and $H^\pm$ masses for $m_h^{0}=126$ GeV$/c^2$.

Primary Result Plots/Tables

Distribution of reconstructed Higgs-boson masses in simulated events, $m_{h^0}=126$ GeV/$c^2$ reconstructed as $m_{bb}$. pdf
Distribution of reconstructed Higgs-boson masses in simulated events, $m_{H^\pm}$ as $m_{Wbb}$. pdf
Distribution of reconstructed Higgs-boson masses in simulated events, $m_{H^0}$ as $m_{WWbb}$. pdf
Distribution of events versus reconstructed $b\bar{b}$ invariant mass ($m_{b\bar{b}}$) for observed data and expected backgrounds in two control regions. Control region consisting of events with at least four jets, at least one $b$-tag and $m_{WWbb}<450$ GeV$/c^2$. The lower panels give the relative difference between the observed and expected distributions; the hatched areas show the combined statistical and systematic uncertainties of the expected background. The small dip near 80 GeV$/c^2$ is mainly due to the $W$-boson mass reconstruction. pdf
Distribution of events versus reconstructed $b\bar{b}$ invariant mass ($m_{b\bar{b}}$) for observed data and expected backgrounds in two control regions.Control region consisting of events with at least four jets, at least one $b$-tag and $m_{Wbb}<250$ GeV$/c^2$. The lower panels give the relative difference between the observed and expected distributions; the hatched areas show the combined statistical and systematic uncertainties of the expected background. The small dip near 80 GeV$/c^2$ is mainly due to the $W$-boson mass reconstruction. pdf
Distribution of events versus reconstructed $b\bar{b}$ invariant mass ($m_{b\bar{b}}$), for observed data and expected backgrounds in the signal region. A signal hypothesis is shown, assuming a total cross section of 250 fb, $m_{H^0}=500$ GeV$/c^2$, and $m_{H^\pm}=300$ GeV$/c^2$. pdf
Upper limits at 95\% C.L. on the cross section times branching fraction as a function of the Higgs-boson masses $m_{H^\pm}$ and $m_{H^0}$; $m_{h^0}$ is fixed to 126 GeV$/c^2$ in each case. Diamonds show the grid of probed masses; the intermediate values are interpolated. pdf

Supporting Results Plots and Tables

Signal region definitions and expected and observed 95\% C.L. upper limits on the production cross section times branching fraction for each Higgs-boson mass hypothesis.
Contributions to the systematic uncertainty on the expected numbers of events for the two main background processes, the total background yield, and an example $500$ GeV$/c^2$ Higgs-boson signal with an assumed total cross section of 1 pb.
Expected upper limits at 95\% C.L. on the cross section times branching fraction as a function of the Higgs-boson masses $m_{H^\pm}$ and $m_{H^0}$; $m_{h^0}$ is fixed to 126 GeV$/c^2$ in each case. Diamonds show the grid of probed masses; the intermediate values are interpolated.