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| CMS-HIG-25-003 ; CERN-EP-2026-201 | ||
| Off-shell Higgs boson measurements: Yukawa couplings, self-coupling, compositeness, and width | ||
| CMS Collaboration | ||
| 25 July 2026 | ||
| Submitted to Physical Review D | ||
| Abstract: Measurements of Higgs boson production in the off-shell region are presented, using the four-lepton decay channel. Data from proton-proton collisions at the CERN LHC, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb$ ^{-1} $ at a center-of-mass energy of 13 TeV, are utilized. The first direct test of composite Higgs boson models is performed, with a lower limit on the compositeness scale $ \Lambda_\mathrm{H} $ set at 870 GeV at the 95% confidence level. Tests of gluon-fusion production within the standard model effective field theory framework are performed. The first constraint on the Higgs boson self-coupling in the off-shell region is obtained. By combining on- and off-shell measurements, the analysis sets the tightest constraints to date on light-quark Yukawa couplings, while relaxing assumptions such as the bound on the Higgs boson coupling to vector bosons, thereby providing more model-independent results. Constraints on the Higgs boson width are provided while accounting for a range of beyond-the-standard-model effects, including both light and heavy particles in the gluon-fusion production loop, as well as modified couplings to vector bosons. A combined analysis of the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ and $ \mathrm{H}\to\mathrm{W}\mathrm{W} $ channels is performed to improve sensitivity to the Higgs boson width, yielding $ \Gamma_{\mathrm{H}}= $ 5.1 $ ^{+2.0}_{-1.8} $ MeV. The scenario of no off-shell Higgs boson production is excluded at a confidence level exceeding 5 standard deviations. | ||
| Links: e-print arXiv:2607.23352 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Leading-order Feynman diagrams for the Higgs boson production processes considered in the off-shell region: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). |
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Figure 1-a:
Leading-order Feynman diagrams for the Higgs boson production processes considered in the off-shell region: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). |
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Figure 1-b:
Leading-order Feynman diagrams for the Higgs boson production processes considered in the off-shell region: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). |
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Figure 1-c:
Leading-order Feynman diagrams for the Higgs boson production processes considered in the off-shell region: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). |
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Figure 1-d:
Leading-order Feynman diagrams for the Higgs boson production processes considered in the off-shell region: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). |
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Figure 2:
The leading-order Feynman diagram illustrating the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $ decay process. |
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Figure 3:
The pre-fit $ m_{4\ell} $ distributions (left) and the combined discriminants (right) in the off-shell region are shown for the untagged (upper), $ \mathrm{VBF} $-tagged (middle), and VH-tagged (lower) categories, divided by the bin width. The legend shows the expected signal, background, or their combined yield with interference for the various processes. The ratio of observation to expectation is displayed in the subpanel below the main plot with a ${\pm}$1 standard deviation uncertainty band in yellow. The dashed curve labeled ``Without H'' denotes the no-off-shell-H-production hypothesis. |
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Figure 3-a:
The pre-fit $ m_{4\ell} $ distributions (left) and the combined discriminants (right) in the off-shell region are shown for the untagged (upper), $ \mathrm{VBF} $-tagged (middle), and VH-tagged (lower) categories, divided by the bin width. The legend shows the expected signal, background, or their combined yield with interference for the various processes. The ratio of observation to expectation is displayed in the subpanel below the main plot with a ${\pm}$1 standard deviation uncertainty band in yellow. The dashed curve labeled ``Without H'' denotes the no-off-shell-H-production hypothesis. |
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Figure 3-b:
The pre-fit $ m_{4\ell} $ distributions (left) and the combined discriminants (right) in the off-shell region are shown for the untagged (upper), $ \mathrm{VBF} $-tagged (middle), and VH-tagged (lower) categories, divided by the bin width. The legend shows the expected signal, background, or their combined yield with interference for the various processes. The ratio of observation to expectation is displayed in the subpanel below the main plot with a ${\pm}$1 standard deviation uncertainty band in yellow. The dashed curve labeled ``Without H'' denotes the no-off-shell-H-production hypothesis. |
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Figure 3-c:
The pre-fit $ m_{4\ell} $ distributions (left) and the combined discriminants (right) in the off-shell region are shown for the untagged (upper), $ \mathrm{VBF} $-tagged (middle), and VH-tagged (lower) categories, divided by the bin width. The legend shows the expected signal, background, or their combined yield with interference for the various processes. The ratio of observation to expectation is displayed in the subpanel below the main plot with a ${\pm}$1 standard deviation uncertainty band in yellow. The dashed curve labeled ``Without H'' denotes the no-off-shell-H-production hypothesis. |
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Figure 4:
Evolution of EW production of the Higgs boson as a function of $ m_{4\ell} $ for selected values of the compositeness scale $ \Lambda_{\mathrm{H}} $: H-only production (left) and the combined four-lepton distribution including Higgs boson signal, background, and interference (right). The background-only scenario (``Without H'') is indicated by the dashed line on the right. |
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Figure 4-a:
Evolution of EW production of the Higgs boson as a function of $ m_{4\ell} $ for selected values of the compositeness scale $ \Lambda_{\mathrm{H}} $: H-only production (left) and the combined four-lepton distribution including Higgs boson signal, background, and interference (right). The background-only scenario (``Without H'') is indicated by the dashed line on the right. |
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Figure 4-b:
Evolution of EW production of the Higgs boson as a function of $ m_{4\ell} $ for selected values of the compositeness scale $ \Lambda_{\mathrm{H}} $: H-only production (left) and the combined four-lepton distribution including Higgs boson signal, background, and interference (right). The background-only scenario (``Without H'') is indicated by the dashed line on the right. |
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Figure 5:
Observed (solid) and expected (dashed) profile-likelihood scans for $ \Lambda_{\mathrm{H}} $ from fits using off-shell production only (blue squares) and combined on- and off-shell production (red circles). Markers indicate the discrete $ \Lambda_{\mathrm{H}} $ points profiled. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 6:
Observed (solid) and expected (dashed) scans for the couplings $ \kappa_{\mathrm{t}} $ (upper left), $ \kappa_{Q} $ (upper right), $ \widetilde{\kappa}_{\mathrm{t}} $ (lower left), and $ \widetilde{\kappa}_{Q} $ (lower right), obtained from the combined on- and off-shell fit. All four couplings, together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $, are allowed to vary simultaneously. The horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 6-a:
Observed (solid) and expected (dashed) scans for the couplings $ \kappa_{\mathrm{t}} $ (upper left), $ \kappa_{Q} $ (upper right), $ \widetilde{\kappa}_{\mathrm{t}} $ (lower left), and $ \widetilde{\kappa}_{Q} $ (lower right), obtained from the combined on- and off-shell fit. All four couplings, together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $, are allowed to vary simultaneously. The horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 6-b:
Observed (solid) and expected (dashed) scans for the couplings $ \kappa_{\mathrm{t}} $ (upper left), $ \kappa_{Q} $ (upper right), $ \widetilde{\kappa}_{\mathrm{t}} $ (lower left), and $ \widetilde{\kappa}_{Q} $ (lower right), obtained from the combined on- and off-shell fit. All four couplings, together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $, are allowed to vary simultaneously. The horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 6-c:
Observed (solid) and expected (dashed) scans for the couplings $ \kappa_{\mathrm{t}} $ (upper left), $ \kappa_{Q} $ (upper right), $ \widetilde{\kappa}_{\mathrm{t}} $ (lower left), and $ \widetilde{\kappa}_{Q} $ (lower right), obtained from the combined on- and off-shell fit. All four couplings, together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $, are allowed to vary simultaneously. The horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 6-d:
Observed (solid) and expected (dashed) scans for the couplings $ \kappa_{\mathrm{t}} $ (upper left), $ \kappa_{Q} $ (upper right), $ \widetilde{\kappa}_{\mathrm{t}} $ (lower left), and $ \widetilde{\kappa}_{Q} $ (lower right), obtained from the combined on- and off-shell fit. All four couplings, together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $, are allowed to vary simultaneously. The horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 7:
Leading-order Feynman diagram illustrating the direct quark-antiquark annihilation channel for Higgs boson production. |
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Figure 8:
Observed (solid) and expected (dashed) profile scans of the Higgs boson coupling modifiers to the light quarks: $ \kappa_{\mathrm{u}} $ (up, upper left), $ \kappa_{\mathrm{d}} $ (down, upper right), $ \kappa_{\mathrm{s}} $ (strange, lower left), and $ \kappa_{\mathrm{c}} $ (charm, lower right), shown for four analysis configurations: on-shell only or combined on- and off-shell production, and with or without the assumptions $ |\kappa_{\mathrm{Z}}|\leq $ 1 and $ \kappa_{\mathrm{Z}}=\kappa_{\mathrm{W}} $. In each scan the other light-quark couplings are profiled simultaneously. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 8-a:
Observed (solid) and expected (dashed) profile scans of the Higgs boson coupling modifiers to the light quarks: $ \kappa_{\mathrm{u}} $ (up, upper left), $ \kappa_{\mathrm{d}} $ (down, upper right), $ \kappa_{\mathrm{s}} $ (strange, lower left), and $ \kappa_{\mathrm{c}} $ (charm, lower right), shown for four analysis configurations: on-shell only or combined on- and off-shell production, and with or without the assumptions $ |\kappa_{\mathrm{Z}}|\leq $ 1 and $ \kappa_{\mathrm{Z}}=\kappa_{\mathrm{W}} $. In each scan the other light-quark couplings are profiled simultaneously. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 8-b:
Observed (solid) and expected (dashed) profile scans of the Higgs boson coupling modifiers to the light quarks: $ \kappa_{\mathrm{u}} $ (up, upper left), $ \kappa_{\mathrm{d}} $ (down, upper right), $ \kappa_{\mathrm{s}} $ (strange, lower left), and $ \kappa_{\mathrm{c}} $ (charm, lower right), shown for four analysis configurations: on-shell only or combined on- and off-shell production, and with or without the assumptions $ |\kappa_{\mathrm{Z}}|\leq $ 1 and $ \kappa_{\mathrm{Z}}=\kappa_{\mathrm{W}} $. In each scan the other light-quark couplings are profiled simultaneously. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 8-c:
Observed (solid) and expected (dashed) profile scans of the Higgs boson coupling modifiers to the light quarks: $ \kappa_{\mathrm{u}} $ (up, upper left), $ \kappa_{\mathrm{d}} $ (down, upper right), $ \kappa_{\mathrm{s}} $ (strange, lower left), and $ \kappa_{\mathrm{c}} $ (charm, lower right), shown for four analysis configurations: on-shell only or combined on- and off-shell production, and with or without the assumptions $ |\kappa_{\mathrm{Z}}|\leq $ 1 and $ \kappa_{\mathrm{Z}}=\kappa_{\mathrm{W}} $. In each scan the other light-quark couplings are profiled simultaneously. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 8-d:
Observed (solid) and expected (dashed) profile scans of the Higgs boson coupling modifiers to the light quarks: $ \kappa_{\mathrm{u}} $ (up, upper left), $ \kappa_{\mathrm{d}} $ (down, upper right), $ \kappa_{\mathrm{s}} $ (strange, lower left), and $ \kappa_{\mathrm{c}} $ (charm, lower right), shown for four analysis configurations: on-shell only or combined on- and off-shell production, and with or without the assumptions $ |\kappa_{\mathrm{Z}}|\leq $ 1 and $ \kappa_{\mathrm{Z}}=\kappa_{\mathrm{W}} $. In each scan the other light-quark couplings are profiled simultaneously. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 9:
Feynman diagrams illustrating the loop-induced correction from the Higgs boson self-interaction in the propagator (upper) and in the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ decay (lower). Here, the black square represents the triple Higgs boson vertex. |
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Figure 9-a:
Feynman diagrams illustrating the loop-induced correction from the Higgs boson self-interaction in the propagator (upper) and in the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ decay (lower). Here, the black square represents the triple Higgs boson vertex. |
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Figure 9-b:
Feynman diagrams illustrating the loop-induced correction from the Higgs boson self-interaction in the propagator (upper) and in the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ decay (lower). Here, the black square represents the triple Higgs boson vertex. |
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Figure 10:
Feynman diagrams illustrating the correction from the Higgs boson self-interaction in the production processes considered in Fig. 1: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). Here, the black square represents the triple Higgs boson vertex. |
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Figure 10-a:
Feynman diagrams illustrating the correction from the Higgs boson self-interaction in the production processes considered in Fig. 1: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). Here, the black square represents the triple Higgs boson vertex. |
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Figure 10-b:
Feynman diagrams illustrating the correction from the Higgs boson self-interaction in the production processes considered in Fig. 1: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). Here, the black square represents the triple Higgs boson vertex. |
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Figure 10-c:
Feynman diagrams illustrating the correction from the Higgs boson self-interaction in the production processes considered in Fig. 1: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). Here, the black square represents the triple Higgs boson vertex. |
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Figure 10-d:
Feynman diagrams illustrating the correction from the Higgs boson self-interaction in the production processes considered in Fig. 1: $ \mathrm{g}\mathrm{g}\mathrm{H} $ (upper left), VH associated production (upper right), $ s $-channel VBF (lower left), and $ t $-channel VBF (lower right). Here, the black square represents the triple Higgs boson vertex. |
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Figure 11:
Distributions of $ m_{4\ell} $ in simulation showing the background (black), the absolute value of the interference between the SM signal and background (gray), and the signal for various $ \kappa_{\lambda} $ values: $ \kappa_{\lambda}= $ 1 (red), 10 (blue), 20 (orange), and 30 (brown). |
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Figure 12:
Observed (solid) and expected (dashed) profile likelihood scans from the fit for $ \kappa_{\lambda} $. The black horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 13:
Observed (solid) and expected (dashed) scans of $ \Gamma_{\mathrm{H}} $ for $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $ under the five progressively inclusive BSM scenarios described in the text. The black horizontal dashed lines indicate the 68 and 95% CL thresholds. |
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Figure 14:
Left: Observed (solid) and expected (dashed) scans of $ \Gamma_\mathrm{H} $ for on- and off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $, and in combination with off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to2\ell2\nu $, and with on- and off-shell $ \mathrm{H}\to\mathrm{W}\mathrm{W}\to2\ell2\nu $. Right: The off-shell signal strength, $ \mu^{\text{off}} $. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 14-a:
Left: Observed (solid) and expected (dashed) scans of $ \Gamma_\mathrm{H} $ for on- and off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $, and in combination with off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to2\ell2\nu $, and with on- and off-shell $ \mathrm{H}\to\mathrm{W}\mathrm{W}\to2\ell2\nu $. Right: The off-shell signal strength, $ \mu^{\text{off}} $. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
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Figure 14-b:
Left: Observed (solid) and expected (dashed) scans of $ \Gamma_\mathrm{H} $ for on- and off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $, and in combination with off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to2\ell2\nu $, and with on- and off-shell $ \mathrm{H}\to\mathrm{W}\mathrm{W}\to2\ell2\nu $. Right: The off-shell signal strength, $ \mu^{\text{off}} $. The black horizontal dashed lines mark the 68 and 95% CL thresholds. |
| Tables | |
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Table 1:
Summary of the observed and expected constraints on the parameters describing Higgs boson substructure, $ \Lambda_{\mathrm{H}} $ and $ d $, obtained from $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $. For each parameter the table lists the central value together with the 68 and 95% CL intervals. The hyphens at the 95% CL indicate that none of the tested hypotheses can be excluded. |
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Table 2:
Summary of the heavy-quark Yukawa coupling measurements for $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $, showing central values with 68% CL uncertainties and 95% CL intervals (in square brackets), obtained from the combined on- and off-shell fit in which all heavy-quark couplings are allowed to vary simultaneously together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $. |
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Table 3:
Summary of the light-quark Yukawa coupling measurements for the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $ channel, showing central values with 68% CL uncertainties and 95% CL intervals (in square brackets). Results are obtained with all other light-quark couplings profiled simultaneously together with $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $. |
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Table 4:
Summary of the light-quark Yukawa coupling measurements using the parameters $ \overline{\kappa}_{\mathrm{q}}=\kappa_{\mathrm{q}} m_{\mathrm{q}}/m_{\mathrm{b}} $, where the values for $ \kappa_{\mathrm{q}} $ are taken from Table. 3, showing central values with 68% CL uncertainties and 95% CL intervals (in square brackets) for the $ PH\to\mathrm{Z}\mathrm{Z}\to4\ell $ channel. Results are obtained with all other light-quark couplings and $ \kappa_{\mathrm{Z}} $ and $ \kappa_{\mathrm{W}} $ profiled. |
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Table 5:
Summary of the $ \kappa_\lambda $ measurements, showing the 68% CL (central values with uncertainties) and 95% CL (in square brackets) intervals for the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $. |
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Table 6:
Summary of the measurements of the total $ \Gamma_\mathrm{H} $, showing the 68 and 95% CL intervals for $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $ under the five progressively more inclusive BSM scenarios discussed in text. |
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Table 7:
Summary of the measurements of the total $ \Gamma_\mathrm{H} $, showing the 68 and 95% CL intervals for on- and off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $, combination with off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to2\ell2\nu $, and with on- and off-shell $ \mathrm{H}\to\mathrm{W}\mathrm{W}\to2\ell2\nu $. |
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Table 8:
Summary of the combined measurement for $ \mu^\text{off} $, showing the 68 and 95% CL intervals for on- and off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to4\ell $ in combination with off-shell $ \mathrm{H}\to\mathrm{Z}\mathrm{Z}\to2\ell2\nu $ and on- and off-shell $ \mathrm{H}\to\mathrm{W}\mathrm{W}\to2\ell2\nu $. |
| Summary |
| Using a data set of proton-proton collisions at $ \sqrt{s}= $ 13 TeV, corresponding to an integrated luminosity of 138 fb$ ^{-1} $, and improved observables, a unified study of Higgs boson production that exploits both on-shell and off-shell regions in $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ decays was performed. The off-shell region provides distinctive shape information that complements rate measurements, and combining on- and off-shell data allows for a range of physics scenarios with reduced model dependence to be probed. Four classes of effects were tested. First, Higgs boson compositeness was probed through a $ q^{2} $-dependent form factor (where $ q^{2} $ is the squared four-momentum transfer of the Higgs boson), and a lower limit of $ \Lambda_{\mathrm{H}} > $ 870 GeV was set on the compositeness scale at 95% confidence level. Second, possible heavy colored states in the gluon-fusion loop were tested by fitting $ CP $-even and $ CP $-odd modifications of the top and a generic heavy quark ($ \kappa_{\mathrm{t}},\kappa_{\PQQ},\widetilde{\kappa}_{\mathrm{t}},\widetilde{\kappa}_{\PQQ} $). These limits can be presented as direct bounds on the couplings to the Higgs boson or translated into constraints on the corresponding standard model effective field theory (SMEFT) Wilson coefficients. Third, by combining on- and off-shell measurements, $ CP $-even deviations of the light-quark Yukawa couplings ($ \kappa_{\mathrm{u}},\kappa_{\mathrm{d}},\kappa_{\mathrm{s}},\kappa_{\mathrm{c}} $) were constrained, where the off-shell information is crucial because it allows for relaxed on-shell assumptions (for example $ |\kappa_\mathrm{V}|\leq $ 1) while retaining meaningful bounds. Fourth, off-shell kinematic information was utilized to probe the Higgs boson trilinear coupling $ \kappa_{\lambda} $ via the SMEFT operator $ \mathcal{O}_{6}=(H^{\dagger}H)^{3} $. The limits are complementary to on-shell and double-H searches because they exploit different kinematic shape signatures. Finally, the total Higgs boson width $ \Gamma_\mathrm{H} $ was investigated under progressively more general BSM hypotheses: relaxing custodial symmetry, profiling the heavy- and light-sector couplings separately, and then profiling all parameters. The off-shell method was found to be robust: introducing additional BSM degrees of freedom either reveals a direct BSM signature or leaves a strong constraint on $ \Gamma_{\mathrm{H}} $ with only modest loss of precision. A new $ \sqrt{s}= $ 13 TeV combination including the $ \mathrm{H}\to\mathrm{Z}\mathrm{Z} $ and $ \mathrm{H}\to\mathrm{W}\mathrm{W} $ channels was performed to maximize sensitivity to $ \Gamma_{\mathrm{H}} $, yielding $ \Gamma_{\mathrm{H}}= $ 5.1 $ ^{+2.0}_{-1.8} $ MeV and a 95% confidence-level interval of 1.7 to 9.4 MeV. The hypothesis of no off-shell Higgs boson production was excluded at the 5 standard deviation level. Taken together, these measurements showed that off-shell analyses substantially broaden the Higgs boson program: they deliver shape-based sensitivity to substructure, loop effects, light-quark Yukawa couplings, and the self-coupling, and they produce a BSM-aware and precise combined constraint on the total width of the Higgs boson. |
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