Updated Combination of CDF and D0 Searches for Standard Model Higgs Boson Production with up to 10.0 fb-1 of Data

TL;DR

This paper reports an updated, comprehensive combination of SM Higgs boson searches from the CDF and D0 collaborations at the Tevatron, synthesizing data across multiple production modes and decay channels with refined analysis techniques. Using up to ~10 fb^-1 per experiment and two independent statistical frameworks, the study achieves extended exclusion ranges and reveals a local excess near m_H ~ 120–130 GeV/c^2, driven predominantly by H→bb channels, with a global significance around 2.5σ after accounting for the look-elsewhere effect. The results provide a holistic assessment of Higgs production in pp̄ collisions at 1.96 TeV, and demonstrate improved sensitivity through expanded datasets, additional final states, and sophisticated treatment of systematics and correlations. The work highlights the complementary sensitivity of H→bb and H→WW channels and informs subsequent Higgs searches at higher-energy colliders.

Abstract

We combine results from the CDF and D0 Collaborations on direct searches for the standard model (SM) Higgs boson (H) in ppbar collisions at the Fermilab Tevatron at sqrt(s)=1.96 TeV. Compared to the previous Tevatron Higgs boson search combination, more data have been included, additional channels have been incorporated, and some previously used channels have been reanalyzed to gain sensitivity. Searches are carried out for hypothesized Higgs boson masses between 100 and 200 GeV/c^2. With up to 10 fb-1 of luminosity analyzed, the 95% C.L. median expected upper limits on Higgs boson production are factors of 0.89, 1.08, and 0.48 times the values of the SM cross section for Higgs bosons of mass m_H=115 GeV/c^2, 125 GeV/c^2, and 165 GeV/c^2, respectively. In the absence of signal, we expect to exclude the regions 100<m_{H}<120 GeV/c^2 and 139<m_H<184 GeV/c^2. We exclude, at the 95% CL, two regions: 100<m_H<103 GeV/c^2, and 147<m_H<180 GeV/c^2. There is a significant excess of data events with respect to the background estimation in the mass range 115<m_H<140 GeV/c^2, which causes our observed limits to not be as stringent as expected. At m_H=120 GeV/c^2, the p-value for a background fluctuation to produce this excess is \sim1.5x10^-3, corresponding to a local significance of 3.0 standard deviations. The global significance for such an excess anywhere in the full mass range investigated is approximately 2.5 standard deviations. We also combine separately searches for H to bb and H to WW. We find that the excess is concentrated in the H to bb channel, appearing in the searches over a broad range of m_H. The maximum local significance of 3.2 standard deviations corresponds to a global significance of approximately 2.9 standard deviations. Our results in the H to WW channels are also consistent with the possible presence of a low-mass Higgs boson.

Figures (29)

• Figure 1: Distributions of $\log_{10}(s/b)$, for the data from all contributing channels from CDF and D0, for Higgs boson masses of 115, 125, 135, and 165 GeV/$c^2$. The data are shown with points, and the expected signal is shown stacked on top of the backgrounds, which have been fit to the data within their systematic uncertainties. Underflows and overflows are collected into the leftmost and rightmost bins, respectively.
• Figure 2: Integrated distributions of $s/b$, starting at the high $s/b$ side, for Higgs boson masses of 115, 125, 135, and 165 GeV/$c^2$. The total signal+background and background-only integrals are shown separately, along with the data sums. Data are only shown for bins that have data events in them. Only the statistical errors, which are correlated point-to-point, are shown.
• Figure 3: Background-subtracted data distributions for all channels, summed in bins of $s/b$, for Higgs boson masses of 115, 125, 135, and 165 GeV/$c^2$. The background has been fit, within its systematic uncertainties and assuming no Higgs boson signal is present, to the data. The points with error bars indicate the background-subtracted data; the sizes of the error bars are the square roots of the predicted background in each bin. The unshaded (blue-outline) histogram shows the systematic uncertainty on the best-fit background model, and the shaded histogram shows the expected signal for a standard model Higgs boson.
• Figure 4: Distributions of $\log_{10}(s/b)$, for the data from the $WH\rightarrow \ell\nu b\bar{b}$, $ZH\rightarrow \nu\bar{\nu} b\bar{b}$, and $ZH\rightarrow \ell^+ \ell^- b\bar{b}$ searches from CDF and D0, for Higgs boson masses of 115, 125, 130, and 135 GeV/$c^2$. The data are shown with points, and the expected signal is shown stacked on top of the backgrounds, which have been fit to the data within their systematic uncertainties. Underflows and overflows are collected into the leftmost and rightmost bins, respectively.
• Figure 5: Integrated distributions of $s/b$, starting at the high $s/b$ side, for Higgs boson masses of 115, 125, 130, and 135 GeV/$c^2$, for the CDF and D0 $WH\rightarrow \ell\nu b\bar{b}$, $ZH\rightarrow \nu\bar{\nu} b\bar{b}$, and $ZH\rightarrow \ell^+ \ell^- b\bar{b}$ searches. The total signal+background and background-only integrals are shown separately, along with the data sums. Data are only shown for bins that have data events in them. Only the statistical errors, which are correlated point-to-point, are shown.