Measurement of the associated production of a Higgs boson decaying into $b$-quarks with a vector boson at high transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

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Measurement of the associated production of a Higgs boson decaying into $b$-quarks with a vector boson at high transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector 4 August 2020
Contact: ATLAS Higgs conveners
e-print arXiv:2008.02508, Physics Briefing	pdf from arXiv
Inspire record	-
Figures Tables Auxiliary Material	-
Abstract
The associated production of a Higgs boson with a $W$ or $Z$ boson decaying into leptons and where the Higgs boson decays to a $b\bar{b}$ pair is measured in the high vector-boson transverse momentum regime, above 250 GeV, with the ATLAS detector. The analysed data, corresponding to an integrated luminosity of 139 fb$^{-1}$, were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is $0.72 ^{+0.39}_{-0.36}$ corresponding to an observed (expected) significance of 2.1 (2.7) standard deviations. Cross-sections of associated production of a Higgs boson decaying into $b$ quark pairs with a $W$ or $Z$ gauge boson, decaying into leptons, are measured in two exclusive transverse momentum regions, 250-400 GeV and above 400 GeV, and interpreted as constraints on anomalous couplings in the framework of a Standard Model effective field theory.
Figures
Figure 01a: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (138kB) pdf (19kB)
Figure 01b: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (145kB) pdf (20kB)
Figure 01c: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (128kB) pdf (19kB)
Figure 01d: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (142kB) pdf (20kB)
Figure 01e: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (127kB) pdf (18kB)
Figure 01f: The m_J post-fit distributions in (a, b) the 0-lepton, (c, d) 1-lepton and (e, f) 2-lepton signal regions for 2-b-tagged events for (a, c, e) 250 GeV<p_T^V<400 GeV and (b, d, f) p_T^V ≥ 400 GeV. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels are merged in this figure. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (132kB) pdf (19kB)
Figure 02a: The m_J post-fit distributions in the tt̄ control region for (a, b) the 0-lepton channel and the 1-lepton channel for 250 GeV<p_T^V<400 GeV and (c, d) the 0-lepton channel and the 1-lepton channel for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 2. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (128kB) pdf (18kB)
Figure 02b: The m_J post-fit distributions in the tt̄ control region for (a, b) the 0-lepton channel and the 1-lepton channel for 250 GeV<p_T^V<400 GeV and (c, d) the 0-lepton channel and the 1-lepton channel for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 2. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (133kB) pdf (20kB)
Figure 02c: The m_J post-fit distributions in the tt̄ control region for (a, b) the 0-lepton channel and the 1-lepton channel for 250 GeV<p_T^V<400 GeV and (c, d) the 0-lepton channel and the 1-lepton channel for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 2. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (127kB) pdf (18kB)
Figure 02d: The m_J post-fit distributions in the tt̄ control region for (a, b) the 0-lepton channel and the 1-lepton channel for 250 GeV<p_T^V<400 GeV and (c, d) the 0-lepton channel and the 1-lepton channel for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 2. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal and background is shown in the lower panel. png (129kB) pdf (20kB)
Figure 03a: (a) m_J distribution in data after subtraction of all backgrounds except for the WZ and ZZ diboson processes. The contributions from all lepton channels and signal regions are summed and weighted by their respective values of the ratio of fitted Higgs boson signal and background yields. The expected contribution of the associated WH and ZH production of a SM Higgs boson with m_H = 125 GeV is shown scaled by the measured combined signal strength (μ_VH^bb=0.72). The diboson contribution is normalised to its best-fit value of μ_VZ^bb=0.91. The size of the combined statistical and systematic uncertainty is indicated by the hatched band. This error band is computed from a full signal-plus-background fit including all the systematic uncertainties defined in Section 7, except for the VH/VZ experimental and theory uncertainties. (b) Fitted values of the Higgs boson signal strength parameter, μ_VH^bb, for mH=125 GeV for the 0-, 1- and 2-lepton channels in different p_T^V regions separately and for various combinations. png (73kB) pdf (16kB)
Figure 03b: (a) m_J distribution in data after subtraction of all backgrounds except for the WZ and ZZ diboson processes. The contributions from all lepton channels and signal regions are summed and weighted by their respective values of the ratio of fitted Higgs boson signal and background yields. The expected contribution of the associated WH and ZH production of a SM Higgs boson with m_H = 125 GeV is shown scaled by the measured combined signal strength (μ_VH^bb=0.72). The diboson contribution is normalised to its best-fit value of μ_VZ^bb=0.91. The size of the combined statistical and systematic uncertainty is indicated by the hatched band. This error band is computed from a full signal-plus-background fit including all the systematic uncertainties defined in Section 7, except for the VH/VZ experimental and theory uncertainties. (b) Fitted values of the Higgs boson signal strength parameter, μ_VH^bb, for mH=125 GeV for the 0-, 1- and 2-lepton channels in different p_T^V regions separately and for various combinations. png (78kB) pdf (16kB)
Figure 04: Measured VH reduced stage-1.2 simplified template cross-sections times the H → bb̄ and V → leptons branching fractions. png (95kB) pdf (16kB)
Figure 05: Summary of the observed individual confidence interval at 68% (solid lines) and 95% (dashed lines) CL for the c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\| Wilson coefficients from a fit of the STXS, using a linear-only parameterisation (in blue) and including quadratic terms (in orange). png (43kB) pdf (14kB)
Figure 06: The impact of the measured +1σ (solid) and -1σ (dashed) variations of the four eigenvectors on the reduced STXS bins. png (55kB) pdf (15kB)
Figure 07a: The negative log-likelihood profile as a function of the variations of single Wilson coefficients c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\|. Wilson coefficients of all other operators are set to zero. The fits are performed using a linear-only parametrisation of the VH production cross section and the Higgs decay branching fraction (blue lines), and using a parametrisation that includes both linear and quadratic terms into account (orange lines). Observed results are drawn in thick solid lines, thin dashed lines indicate expected results. The 68% and 95% CL lines are also indicated. png (170kB) pdf (17kB)
Figure 07b: The negative log-likelihood profile as a function of the variations of single Wilson coefficients c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\|. Wilson coefficients of all other operators are set to zero. The fits are performed using a linear-only parametrisation of the VH production cross section and the Higgs decay branching fraction (blue lines), and using a parametrisation that includes both linear and quadratic terms into account (orange lines). Observed results are drawn in thick solid lines, thin dashed lines indicate expected results. The 68% and 95% CL lines are also indicated. png (158kB) pdf (16kB)
Figure 07c: The negative log-likelihood profile as a function of the variations of single Wilson coefficients c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\|. Wilson coefficients of all other operators are set to zero. The fits are performed using a linear-only parametrisation of the VH production cross section and the Higgs decay branching fraction (blue lines), and using a parametrisation that includes both linear and quadratic terms into account (orange lines). Observed results are drawn in thick solid lines, thin dashed lines indicate expected results. The 68% and 95% CL lines are also indicated. png (165kB) pdf (17kB)
Figure 07d: The negative log-likelihood profile as a function of the variations of single Wilson coefficients c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\|. Wilson coefficients of all other operators are set to zero. The fits are performed using a linear-only parametrisation of the VH production cross section and the Higgs decay branching fraction (blue lines), and using a parametrisation that includes both linear and quadratic terms into account (orange lines). Observed results are drawn in thick solid lines, thin dashed lines indicate expected results. The 68% and 95% CL lines are also indicated. png (149kB) pdf (18kB)
Figure 07e: The negative log-likelihood profile as a function of the variations of single Wilson coefficients c_Hq⁽³⁾, c_Hu, c_HW, c_HWB and \|c_dH\|. Wilson coefficients of all other operators are set to zero. The fits are performed using a linear-only parametrisation of the VH production cross section and the Higgs decay branching fraction (blue lines), and using a parametrisation that includes both linear and quadratic terms into account (orange lines). Observed results are drawn in thick solid lines, thin dashed lines indicate expected results. The 68% and 95% CL lines are also indicated. png (169kB) pdf (19kB)
Tables
Table 01: Signal and background processes with the corresponding generators used for the nominal samples. If not specified, the order of the cross-section calculation refers to the expansion in the strong coupling constant (α_S). (star) The events were generated using the first PDF in the NNPDF3.0NLO set and subsequently reweighted to the PDF4LHC15NLO set [31] using the internal algorithm in Powheg-Box v2. (†) The NNLO(QCD)+NLO(EW) cross-section calculation for the pp → ZH process already includes the gg→ ZH contribution. The qq→ ZH process is normalised using the cross-section for the pp → ZH process, after subtracting the gg→ ZH contribution. An additional scale factor is applied to the qq → VH processes as a function of the transverse momentum of the vector boson, to account for electroweak (EW) corrections at NLO. This makes use of the VH differential cross-section computed with Hawk [32,33]. png (48kB) pdf (72kB)
Table 02: Event selection requirements for the boosted VH, H→ bb̄ analysis channels and sub-channels. png (55kB) pdf (77kB)
Table 03: Summary of the definition of the analysis regions. Signal enriched regions are marked with the label SR. There are regions with relatively large signal purity (HP SR) and with low purity (LP SR). Background enriched regions are marked with the label CR. The shorthand "add" stands for additional small-R jets, i.e. number of small-R jets not matched to the Higgs-jet candidate.Summary of the definition of the analysis regions. Signal enriched regions are marked with the label SR. There are regions with relatively large signal purity (HP SR) and with low purity (LP SR). Background enriched regions are marked with the label CR. The shorthand "add" stands for additional small-R jets, i.e. number of small-R jets not matched to the Higgs-jet candidate. png (20kB) pdf (53kB)
Table 04: Breakdown of the absolute contributions to the uncertainty in μ_VH^bb inclusive in p_T^V. The sum in quadrature of the systematic uncertainties attached to the categories differs from the total systematic uncertainty due to correlations. The reported values represent the average between the positive and negative uncertainties on μ_VH^bb. png (34kB) pdf (44kB)
Table 05: Measured and predicted VH, V → leptons reduced stage-1.2 simplified template cross sections times the H → bb̄ and V → leptons branching fractions with corresponding uncertainties. All possible Z decays into neutral and charged leptons are considered. png (26kB) pdf (59kB)
Table 06: Wilson coefficients and their corresponding dimension-6 operators in the Warsaw formulation considered in this analysis [101,104]. png (22kB) pdf (57kB)
Table 07: Linear combinations of Wilson coefficients corresponding to the principal component decomposition eigenvectors (coefficients less than 0.10 have been omitted for better readability). The corresponding eigenvalues, representing in the Gaussian approximation the squared inverse uncertainty of the measured eigenvector, is also indicated. png (21kB) pdf (48kB)
Table 08: Expected and observed best-fit values and associated uncertainties (68% CL) from a simultaneous fit of the four coefficients corresponding to the eigenvector combinations. png (10kB) pdf (52kB)
Auxiliary figures and tables
Figure 01: The VH associated production process and the H → bb̄ final state, where the off-shell (V^*) and on-shell (V) vector bosons are W- or Z-bosons subsequently decaying to leptons denoted ℓ representing electrons, muons and/or neutrinos. png (131kB) pdf (16kB)
Figure 02a: Large-R jet mass comparison as additional corrections are applied to the jet energy scale for the signal in the 2-lepton channel and (a) 250 GeV ≤ p_T^V < 400 GeV and (b) p_T^V ≥ 400 GeV regions for the dominant qqZH contribution. The distributions are fit with a Bukin function (arXiv: 0711.4449) and the resolution values, σ, correspond to the width of the fitted function. png (161kB) eps (30kB)
Figure 02b: Large-R jet mass comparison as additional corrections are applied to the jet energy scale for the signal in the 2-lepton channel and (a) 250 GeV ≤ p_T^V < 400 GeV and (b) p_T^V ≥ 400 GeV regions for the dominant qqZH contribution. The distributions are fit with a Bukin function (arXiv: 0711.4449) and the resolution values, σ, correspond to the width of the fitted function. png (163kB) eps (31kB)
Figure 03a: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for 250 GeV<p_T^V<400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (136kB) pdf (19kB)
Figure 03b: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for 250 GeV<p_T^V<400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (132kB) pdf (19kB)
Figure 03c: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for 250 GeV<p_T^V<400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (135kB) pdf (19kB)
Figure 03d: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for 250 GeV<p_T^V<400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (137kB) pdf (20kB)
Figure 04a: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (141kB) pdf (20kB)
Figure 04b: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (143kB) pdf (21kB)
Figure 04c: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (143kB) pdf (20kB)
Figure 04d: The large-R jet mass post-fit distributions in the 0-lepton channel (a) high-purity and (b) low-purity SRs and in the 1-lepton channel (c) high-purity and (d) low-purity SRs for p_T^V>400 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (142kB) pdf (21kB)
Figure 05a: p_T^V postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs and for the (d) 0-lepton and (e) 1-lepton top CRs for 2-b-tagged events for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of ten for (a, b, c) and 100 for (d, e). The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (114kB) pdf (69kB)
Figure 05b: p_T^V postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs and for the (d) 0-lepton and (e) 1-lepton top CRs for 2-b-tagged events for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of ten for (a, b, c) and 100 for (d, e). The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (116kB) pdf (70kB)
Figure 05c: p_T^V postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs and for the (d) 0-lepton and (e) 1-lepton top CRs for 2-b-tagged events for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of ten for (a, b, c) and 100 for (d, e). The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (64kB) pdf (66kB)
Figure 05d: p_T^V postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs and for the (d) 0-lepton and (e) 1-lepton top CRs for 2-b-tagged events for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of ten for (a, b, c) and 100 for (d, e). The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (117kB) pdf (70kB)
Figure 05e: p_T^V postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs and for the (d) 0-lepton and (e) 1-lepton top CRs for 2-b-tagged events for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of ten for (a, b, c) and 100 for (d, e). The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (118kB) pdf (71kB)
Figure 06a: Number of small-R jets non-matched to the Higgs candidate large-R jet postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of five. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (114kB) pdf (16kB)
Figure 06b: Number of small-R jets non-matched to the Higgs candidate large-R jet postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of five. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (120kB) pdf (16kB)
Figure 06c: Number of small-R jets non-matched to the Higgs candidate large-R jet postfit distribution in (a) 0-lepton, (b) 1-lepton and (c) 2-lepton SRs for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of five. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (112kB) pdf (16kB)
Figure 07a: Number of additional b-tagged VR track-jets non-matched to the Higgs candidate large-R jet in the event postfit distribution in (a) 0-lepton and (b) 1-lepton for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 20. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (62kB) pdf (15kB)
Figure 07b: Number of additional b-tagged VR track-jets non-matched to the Higgs candidate large-R jet in the event postfit distribution in (a) 0-lepton and (b) 1-lepton for p_T^V>250 GeV. The background contributions after the likelihood fit are shown as filled histograms. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram on top of the fitted backgrounds normalised to the signal yield extracted from data (μ_VH^bb=0.72), and unstacked as an unfilled histogram, scaled by the SM prediction times a factor of 20. The size of the combined statistical and systematic uncertainty for the sum of the fitted signal and background is indicated by the hatched band. The highest bin in the distributions contains the overflow. The ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (101kB) pdf (15kB)
Figure 08a: Large-R jet mass distribution combining all three lepton channels and signal regions by (a) stacking them and (b) after background subtraction except for the WZ and ZZ diboson processes. The contributions were not weighted by their respective values of the ratio of fitted Higgs boson signal and background yields. In (a) the size of the combined statistical and systematic uncertainty for the fitted signal and background is indicated by the hatched band, while in (b) the hatched band shows the background only uncertainty. The highest bin in the distributions contains the overflow. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram in red color normalised to the signal yield extracted from data (μ_VH^bb=0.72), and in (a) is also shown unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. In (a) the background contributions after the likelihood fit are shown as filled histograms and the ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (130kB) pdf (18kB)
Figure 08b: Large-R jet mass distribution combining all three lepton channels and signal regions by (a) stacking them and (b) after background subtraction except for the WZ and ZZ diboson processes. The contributions were not weighted by their respective values of the ratio of fitted Higgs boson signal and background yields. In (a) the size of the combined statistical and systematic uncertainty for the fitted signal and background is indicated by the hatched band, while in (b) the hatched band shows the background only uncertainty. The highest bin in the distributions contains the overflow. The Higgs boson signal (m_H = 125 GeV) is shown as a filled histogram in red color normalised to the signal yield extracted from data (μ_VH^bb=0.72), and in (a) is also shown unstacked as an unfilled histogram, scaled by the SM prediction times a factor of two. In (a) the background contributions after the likelihood fit are shown as filled histograms and the ratio of the data to the sum of the fitted signal (μ_VH^bb=0.72) and background is shown in the lower panel. png (71kB) pdf (15kB)
Figure 09: Observed contours at 68% and 95% confidence level (CL) in the (μ_VH^bb, μ_VZ^bb) plane. The cross indicates the best-fit value and the star the SM prediction. The correlation between μ_VH^bb and μ_VZ^bb is 11%. png (55kB) pdf (27kB)
Figure 10: Fitted values of the VZ signal strength parameter, μ_VZ^bb for the 0-, 1- and 2-lepton channels in different p_T^V regions and their combination. The individual μ_VZ^bb values for the lepton channels are obtained from a simultaneous fit with the signal strength parameter for each of the lepton channels floating independently. png (78kB) pdf (16kB)
Figure 11a: The acceptance (in per cent, including the efficiency of the experimental selection) for (a) VH, V→leptons and H→ bb̄ events of each reconstructed-event category (y-axis) for each STXS signal region (x-axis), in percent; (b) the fraction of signal (in percent) from each STXS signal region (x-axis) in every reconstructed-event category (y-axis). Events with ≥ 0 jets are considered. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels have been merged in this figure. Entries with acceptance times efficiency below 0.01% or signal fractions below 0.1% are not shown. png (133kB) pdf (19kB)
Figure 11b: The acceptance (in per cent, including the efficiency of the experimental selection) for (a) VH, V→leptons and H→ bb̄ events of each reconstructed-event category (y-axis) for each STXS signal region (x-axis), in percent; (b) the fraction of signal (in percent) from each STXS signal region (x-axis) in every reconstructed-event category (y-axis). Events with ≥ 0 jets are considered. The low-purity and high-purity categories in the case of the 0-lepton and 1-lepton channels have been merged in this figure. Entries with acceptance times efficiency below 0.01% or signal fractions below 0.1% are not shown. png (133kB) pdf (19kB)
Figure 12a: The acceptance (in per cent, including the efficiency of the experimental selection) for (a) VH, V→leptons and H→ bb̄ events of each reconstructed-event category (y-axis) for each STXS signal region (x-axis), in percent; (b) the fraction of signal (in percent) from each STXS signal region (x-axis) in every reconstructed-event category (y-axis). Numbers are provided separately for events with 0 and ≥ 1 jets. Entries with acceptance times efficiency below 0.01% or signal fractions below 0.1% are not shown. png (166kB) pdf (20kB)
Figure 12b: The acceptance (in per cent, including the efficiency of the experimental selection) for (a) VH, V→leptons and H→ bb̄ events of each reconstructed-event category (y-axis) for each STXS signal region (x-axis), in percent; (b) the fraction of signal (in percent) from each STXS signal region (x-axis) in every reconstructed-event category (y-axis). Numbers are provided separately for events with 0 and ≥ 1 jets. Entries with acceptance times efficiency below 0.01% or signal fractions below 0.1% are not shown. png (174kB) pdf (20kB)
Figure 13: Measured values of the reduced stage-1.2 simplified template VH, H→ bb̄ cross sections, normalised to the Standard Model predictions. The grey error bands correspond to the theoretical uncertainty on the normalised σ × B. png (59kB) pdf (15kB)
Figure 14: Observed correlations between the measured reduced stage-1.2 simplified template VH, V→leptons and H→ bb̄ cross sections, including both the statistical and systematic uncertainties. The colour indicates the size of the correlation. png (109kB) pdf (20kB)
Figure 15: Fitted values of the Higgs boson signal strength parameter μ_VH^bb for the WH and ZH production modes separately, for m_H = 125 GeV. png (45kB) pdf (14kB)
Figure 16: Fitted values of the Higgs boson signal strength parameter μ_VZ^bb for the WZ and ZZ production modes separately, for m_H = 125 GeV. png (45kB) pdf (14kB)
Figure 17: Candidate event for the process WH→ μν bb (Run 338349, Event 616525246). An isolated muon is shown as the lower red track producing hits in the endcap-muon chambers; it has a transverse momentum of 196 GeV and a pseudorapidity of 1.16. The missing transverse momentum is identified by a white dashed line and it has a magnitude of 832 GeV; the transverse momentum (mass) of the muon-E_T^miss system is 1.03 TeV (112 GeV). The Higgs-boson candidate is reconstructed as a single large-radius (R=1.0) jet (blue cone) containing two b-tagged sub-jets built from tracking information. The jet has a transverse momentum of 973 GeV and a mass of 116 GeV. A clear two-prong structure is visible as energy deposits in both the electromagnetic (green) and hadronic (yellow) calorimeters. A second muon (upper red track), shown with hits in the barrel muon chambers, is found within Δ R=1.0 of the Higgs-boson candidate. png (1MB)
Figure 18a: Observed confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients. Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown in blue, including quadratic terms gives rise to the results plotted in orange. The best-fit point is marked by a cross. png (61kB) pdf (29kB)
Figure 18b: Observed confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients. Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown in blue, including quadratic terms gives rise to the results plotted in orange. The best-fit point is marked by a cross. png (57kB) pdf (28kB)
Figure 19a: Expected confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients. Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown in blue, including quadratic terms gives rise to the results plotted in orange. The best-fit point is marked by a cross. png (61kB) pdf (30kB)
Figure 19b: Expected confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients. Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown in blue, including quadratic terms gives rise to the results plotted in orange. The best-fit point is marked by a cross. png (56kB) pdf (28kB)
Figure 20: Summary of the expected (orange) and observed (blue) individual confidence interval at 68% (solid lines) and 95% (dashed lines) CL for the four eigenvectors. png (37kB) pdf (14kB)
Figure 21: The impact of the expected +1σ (solid) and -1σ (dashed) variations of the four eigenvectors on the reduced STXS bins. png (54kB) pdf (15kB)
Figure 22: Summary of the observed 68% (solid lines) and 95% (dashed lines) CL for the Wilson coefficients of Warsaw-basis operators [101] from a fit of the STXSs, using a linear-only parameterisation in blue and including quadratic terms in orange. In addition, the constraint on modifications of the branching ratio Δ BR/BR_SM is included. By definition, this observable has a linear impact. Coefficients are varied individually. png (79kB) pdf (16kB)
Figure 23: Expected results for the negative log-likelihood as a function of a single Wilson coefficient c_Hq⁽³⁾ is shown using the two p_T^V bins in the analysis (solid lines) and using a single bin of p_T^V>250 GeV (dashed lines). Wilson coefficients of all other operators are set to zero, nuisance parameters are profiled out. The blue curves are valid when using a linear parameterisation of the VH production cross section and the Higgs decay branching fraction, while the orange lines also include quadratic terms in the parameterisation. png (164kB) pdf (17kB)
Figure 24a: Expected confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients are shown using the two p_T^V bins in the analysis (blue lines) and using a single bin of p_T^V>250 GeV (orange lines). Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown on the left, including quadratic terms gives rise to the results plotted on the right. The best-fit point is marked by a cross. png (60kB) pdf (27kB)
Figure 24b: Expected confidence interval at 68% (dashed lines) and 95% (solid lines) CL on pairs of Wilson coefficients are shown using the two p_T^V bins in the analysis (blue lines) and using a single bin of p_T^V>250 GeV (orange lines). Limits obtained from a linear parameterisation of the VH production cross section and the partial and total Higgs decay widths are shown on the left, including quadratic terms gives rise to the results plotted on the right. The best-fit point is marked by a cross. png (64kB) pdf (28kB)
Table 01: Post-fit yields in the 0-lepton channel in the high- and low-purity signal regions and in the control regions. The uncertainties are statistical and systematic combined. "-" indicates yields smaller than 0.1. Yields have been computed after propagating the result of the combined fit to all the channels. png (51kB) pdf (48kB)
Table 02: Post-fit yields in the 1-lepton channel in the high- and low-purity signal regions and in the control regions. The uncertainties are statistical and systematic combined. "-" indicates yields smaller than 0.1. Yields have been computed after propagating the result of the combined fit to all the channels. png (53kB) pdf (49kB)
Table 03: Post-fit yields in the 2-lepton channel. The uncertainties are statistical and systematic combined. "-" indicates yields smaller than 0.1. Yields have been computed after propagating the result of the combined fit to all the channels. png (22kB) pdf (46kB)
Table 04: Expected and observed significance for the measured XS in the four STXS bins. The results are obtained from a simultaneous extraction of the four parameters. png (14kB) pdf (32kB)
Table 05: Expected and observed significance for the 0L, 1L and 2L sub-channels and for the WH and ZH production modes separately. png (12kB) pdf (24kB)
Table 06: Observed one-dimensional confidence intervals for all 17 dimension-6 Wilson coefficients of Warsaw-basis operators [101] that affect the signal process at LO, at 68% and 95% CL. Coefficients are varied individually. Numbers are shown for linear-only and linear + quadratic parameterisations. Additionally, the linearized branching ratio parameter Δ BR/BR_SM is shown. png (68kB) pdf (50kB)
Table 07: Expected one-dimensional confidence intervals for all 17 dimension-6 Wilson coefficients of Warsaw-basis operators [101] that affect the signal process at LO, at 68% and 95% CL. Coefficients are varied individually. Numbers are shown for linear-only and linear + quadratic parameterisations. Additionally, the linearized branching ratio parameter Δ BR/BR_SM is shown. png (62kB) pdf (50kB)
Table 08: Linear combinations of Wilson coefficients corresponding to the principal component decomposition eigenvectors. The corresponding eigenvalues, representing in the Gaussian approximation the inverse uncertainty square of the measured eigenvector, is also indicated. png (51kB) pdf (49kB)

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2020-12-11 00:20:41