A search is presented for a heavy resonance decaying into a Z boson and a Higgs (H) boson. The analysis is based on data from proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$, recorded with the CMS experiment in the years 2016-2018. Resonance masses between 1.4 and 5 TeV are considered, resulting in large transverse momenta of the Z and H bosons. Final states that result from Z boson decays to pairs of electrons, muons, or neutrinos are considered. The H boson is reconstructed as a single large-radius jet, recoiling against the Z boson. Machine-learning flavour-tagging techniques are employed to identify decays of a Lorentz-boosted H boson into pairs of charm or bottom quarks, or into four quarks via the intermediate H $\to$ WW* and ZZ* decays. The analysis targets H boson decays that were not generally included in previous searches using the H $\to$$\mathrm{b\bar{b}}$ channel. Compared with previous analyses, the sensitivity for high resonance masses is improved significantly in the channel where at most one b quark is tagged.
The product of signal acceptance and efficiency for signal events as a function of $m_{Z'}$ for the charged-lepton and neutrino channels in the SR. The efficiency is calculated with respect to Z boson decays to charged leptons and neutrinos for the charged-lepton and neutrino channels, respectively. For comparison, the results from the $\leq$ 1 b category of the previous CMS search in the ZH channel are shown as dashed lines.
The product of signal acceptance and efficiency for signal events as a function of $m_{Z'}$ for the charged-lepton and neutrino channels in the SR. The efficiency is calculated with respect to Z boson decays to charged leptons and neutrinos for the charged-lepton and neutrino channels, respectively. For comparison, the results from the $\leq$ 1 b category of the previous CMS search in the ZH channel are shown as dashed lines.
Distributions in $m_{Z'}^{rec}$ for data in the SRs, together with fits of the background functions under the background-only hypothesis for the muon channel. The number of observed events in each bin is divided by the bin width. The signal predictions are shown for different Z' boson masses, normalized to an arbitrary cross section of 1 fb. In the panels below the distributions, the ratios of data to the background function are displayed. The shaded green areas represent the statistical uncertainty from the fit. The $\chi^2$ values per number of degrees of freedom ($\chi^2$/n.d.f.) and the corresponding $p$-values are provided for each fit.
The paper presents a search for supersymmetric particles produced in proton-proton collisions at $\sqrt{s}=$ 13 TeV and decaying into final states with missing transverse momentum and jets originating from charm quarks. The data were taken with the ATLAS detector at the Large Hadron Collider at CERN from 2015 to 2018 and correspond to an integrated luminosity of 139 fb$^{-1}$. No significant excess of events over the expected Standard Model background expectation is observed in optimized signal regions, and limits are set on the production cross-sections of the supersymmetric particles. Pair production of charm squarks or top squarks, each decaying into a charm quark and the lightest supersymmetric particle $\tilde{\chi}^0_1$, is excluded at 95% confidence level for squarks with masses up to 900 GeV for scenarios where the mass of $\tilde{\chi}^0_1$ is below 50 GeV. Additionally, the production of leptoquarks with masses up to 900 GeV is excluded for the scenario where up-type leptoquarks decay into a charm quark and a neutrino. Model-independent limits on cross-sections and event yields for processes beyond the Standard Model are also reported.
Summary of material in this HEPData record. <br/><br/> Truth Code snippets, SLHA files, Madgraph process cards and UFO files for the leptoquark models are available under "Additional Resources" (purple button on the left). <br/><br/> <b>Contours:</b> <ul> SUSY exclusion limits (best-expected SR combination) <ul> <a href="155678?version=1&table=Contour1">Expected</a> <a href="155678?version=1&table=Contour3">+1$\sigma$</a> <a href="155678?version=1&table=Contour2">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour4">Observed</a> <a href="155678?version=1&table=Contour5">+1$\sigma$</a> <a href="155678?version=1&table=Contour6">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (best-expected SR combination) as a function of $\Delta m(\tilde{t}_1,\tilde{\chi}_1^0)$ <ul> <a href="155678?version=1&table=Contour7">Expected</a> <a href="155678?version=1&table=Contour9">+1$\sigma$</a> <a href="155678?version=1&table=Contour8">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour10">Observed</a> <a href="155678?version=1&table=Contour11">+1$\sigma$</a> <a href="155678?version=1&table=Contour12">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-HM1) <ul> <a href="155678?version=1&table=Contour15">Expected</a> <a href="155678?version=1&table=Contour14">+1$\sigma$</a> <a href="155678?version=1&table=Contour13">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour18">Observed</a> <a href="155678?version=1&table=Contour16">+1$\sigma$</a> <a href="155678?version=1&table=Contour17">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-HM2) <ul> <a href="155678?version=1&table=Contour21">Expected</a> <a href="155678?version=1&table=Contour20">+1$\sigma$</a> <a href="155678?version=1&table=Contour19">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour24">Observed</a> <a href="155678?version=1&table=Contour22">+1$\sigma$</a> <a href="155678?version=1&table=Contour23">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-HM3) <ul> <a href="155678?version=1&table=Contour27">Expected</a> <a href="155678?version=1&table=Contour26">+1$\sigma$</a> <a href="155678?version=1&table=Contour25">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour30">Observed</a> <a href="155678?version=1&table=Contour28">+1$\sigma$</a> <a href="155678?version=1&table=Contour29">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-Comp1) <ul> <a href="155678?version=1&table=Contour33">Expected</a> <a href="155678?version=1&table=Contour32">+1$\sigma$</a> <a href="155678?version=1&table=Contour31">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour36">Observed</a> <a href="155678?version=1&table=Contour34">+1$\sigma$</a> <a href="155678?version=1&table=Contour35">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-Comp2) <ul> <a href="155678?version=1&table=Contour39">Expected</a> <a href="155678?version=1&table=Contour38">+1$\sigma$</a> <a href="155678?version=1&table=Contour37">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour42">Observed</a> <a href="155678?version=1&table=Contour40">+1$\sigma$</a> <a href="155678?version=1&table=Contour41">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-Comp3) <ul> <a href="155678?version=1&table=Contour45">Expected</a> <a href="155678?version=1&table=Contour44">+1$\sigma$</a> <a href="155678?version=1&table=Contour43">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour48">Observed</a> <a href="155678?version=1&table=Contour46">+1$\sigma$</a> <a href="155678?version=1&table=Contour47">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (SR-Comp-1c) <ul> <a href="155678?version=1&table=Contour50">Expected</a> <a href="155678?version=1&table=Contour49">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (scan over branching fraction for $m(\tilde{\chi}_1^0)=1$ GeV) <ul> <a href="155678?version=1&table=Contour51">Expected</a> <a href="155678?version=1&table=Contour53">+1$\sigma$</a> <a href="155678?version=1&table=Contour52">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour54">Observed</a> <a href="155678?version=1&table=Contour55">+1$\sigma$</a> <a href="155678?version=1&table=Contour56">-1$\sigma$</a> <br/> </ul> SUSY exclusion limits (scan over branching fraction for $m(\tilde{\chi}_1^0)=200$ GeV) <ul> <a href="155678?version=1&table=Contour57">Expected</a> <a href="155678?version=1&table=Contour59">+1$\sigma$</a> <a href="155678?version=1&table=Contour58">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour60">Observed</a> <a href="155678?version=1&table=Contour61">+1$\sigma$</a> <a href="155678?version=1&table=Contour62">-1$\sigma$</a> <br/> </ul> $\mathrm{LQ}^\mathrm{u}_{21}$ exclusion limits <ul> <a href="155678?version=1&table=Contour65">Expected</a> <a href="155678?version=1&table=Contour64">+1$\sigma$</a> <a href="155678?version=1&table=Contour63">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour68">Observed</a> <a href="155678?version=1&table=Contour66">+1$\sigma$</a> <a href="155678?version=1&table=Contour67">-1$\sigma$</a> <br/> </ul> $\mathrm{LQ}^\mathrm{u}_{22}$ exclusion limits <ul> <a href="155678?version=1&table=Contour71">Expected</a> <a href="155678?version=1&table=Contour70">+1$\sigma$</a> <a href="155678?version=1&table=Contour69">-1$\sigma$</a> <br/> <a href="155678?version=1&table=Contour74">Observed</a> <a href="155678?version=1&table=Contour72">+1$\sigma$</a> <a href="155678?version=1&table=Contour73">-1$\sigma$</a> <br/> </ul> </ul> <b>Cross-section upper limits:</b> <ul> SUSY signals (best-expected SR combination): <a href="155678?version=1&table=Cross-sectionupperlimit1">Observed</a> <br/> $\mathrm{LQ}^\mathrm{u}_{21}$ (combined High-Mass SRs): <a href="155678?version=1&table=Cross-sectionupperlimit2">Observed</a> <br/> $\mathrm{LQ}^\mathrm{u}_{22}$ (combined High-Mass SRs): <a href="155678?version=1&table=Cross-sectionupperlimit3">Observed</a> <br/> $U(1)$ pair (min) (combined High-Mass SRs): <a href="155678?version=1&table=Cross-sectionupperlimit6">Expected</a> <a href="155678?version=1&table=Cross-sectionupperlimit5">+1$\sigma$</a> <a href="155678?version=1&table=Cross-sectionupperlimit4">-1$\sigma$</a> <a href="155678?version=1&table=Cross-sectionupperlimit7">Observed</a> <br/> $U(1)$ pair (YM) (combined High-Mass SRs): <a href="155678?version=1&table=Cross-sectionupperlimit10">Expected</a> <a href="155678?version=1&table=Cross-sectionupperlimit9">+1$\sigma$</a> <a href="155678?version=1&table=Cross-sectionupperlimit8">-1$\sigma$</a> <a href="155678?version=1&table=Cross-sectionupperlimit11">Observed</a> <br/> </ul> <b>Signal region distributions:</b> <ul> <a href="155678?version=1&table=SRdistribution2">$E_\mathrm{T}^\mathrm{miss}$ Sig. in SR-HM1</a> <br/> <a href="155678?version=1&table=SRdistribution3">$m_\mathrm{T}^\mathrm{min}(c)$ in SR-HM2</a> <br/> <a href="155678?version=1&table=SRdistribution4">$R_\mathrm{ISR}$ in SR-Comp1</a> <br/> <a href="155678?version=1&table=SRdistribution5">$R_\mathrm{ISR}$ in SR-Comp2</a> <br/> <a href="155678?version=1&table=SRdistribution6">$R_\mathrm{ISR}$ in SR-Comp3</a> <br/> <a href="155678?version=1&table=SRdistribution1">$R_\mathrm{ISR}$ in SR-Comp-1c</a> <br/> </ul> <b>Acceptances:</b> <ul> SUSY signals: <a href="155678?version=1&table=Acceptance2">SR-HM1</a> <a href="155678?version=1&table=Acceptance3">SR-HM2</a> <a href="155678?version=1&table=Acceptance4">SR-HM3</a> <a href="155678?version=1&table=Acceptance5">SR-HM-Disc</a> <a href="155678?version=1&table=Acceptance6">SR-Comp1</a> <a href="155678?version=1&table=Acceptance7">SR-Comp2</a> <a href="155678?version=1&table=Acceptance8">SR-Comp3</a> <a href="155678?version=1&table=Acceptance1">SR-Comp-1c</a> <br/> $\mathrm{LQ}^\mathrm{u}_{21}$: <a href="155678?version=1&table=Acceptance9">SR-HM1</a> <a href="155678?version=1&table=Acceptance10">SR-HM2</a> <a href="155678?version=1&table=Acceptance11">SR-HM3</a> <a href="155678?version=1&table=Acceptance12">SR-HM-Disc</a> <br/> $\mathrm{LQ}^\mathrm{u}_{22}$: <a href="155678?version=1&table=Acceptance13">SR-HM1</a> <a href="155678?version=1&table=Acceptance14">SR-HM2</a> <a href="155678?version=1&table=Acceptance15">SR-HM3</a> <a href="155678?version=1&table=Acceptance16">SR-HM-Disc</a> <br/> $U(1)$ pair (min): <a href="155678?version=1&table=Acceptance17">SR-HM1</a> <a href="155678?version=1&table=Acceptance18">SR-HM2</a> <a href="155678?version=1&table=Acceptance19">SR-HM3</a> <a href="155678?version=1&table=Acceptance20">SR-HM-Disc</a> <br/> $U(1)$ pair (YM): <a href="155678?version=1&table=Acceptance21">SR-HM1</a> <a href="155678?version=1&table=Acceptance22">SR-HM2</a> <a href="155678?version=1&table=Acceptance23">SR-HM3</a> <a href="155678?version=1&table=Acceptance24">SR-HM-Disc</a> <br/> </ul> <b>Efficiencies:</b> <ul> $U(1)$ pair (min): <a href="155678?version=1&table=Efficiency1">SR-HM1</a> <a href="155678?version=1&table=Efficiency2">SR-HM2</a> <a href="155678?version=1&table=Efficiency3">SR-HM3</a> <a href="155678?version=1&table=Efficiency4">SR-HM-Disc</a> <br/> $U(1)$ pair (YM): <a href="155678?version=1&table=Efficiency5">SR-HM1</a> <a href="155678?version=1&table=Efficiency6">SR-HM2</a> <a href="155678?version=1&table=Efficiency7">SR-HM3</a> <a href="155678?version=1&table=Efficiency8">SR-HM-Disc</a> <br/> </ul> <b>Acceptance times efficiency:</b> <ul> SUSY signals: <a href="155678?version=1&table=Acceptancetimesefficiency2">SR-HM1</a> <a href="155678?version=1&table=Acceptancetimesefficiency3">SR-HM2</a> <a href="155678?version=1&table=Acceptancetimesefficiency4">SR-HM3</a> <a href="155678?version=1&table=Acceptancetimesefficiency5">SR-HM-Disc</a> <a href="155678?version=1&table=Acceptancetimesefficiency6">SR-Comp1</a> <a href="155678?version=1&table=Acceptancetimesefficiency7">SR-Comp2</a> <a href="155678?version=1&table=Acceptancetimesefficiency8">SR-Comp3</a> <a href="155678?version=1&table=Acceptancetimesefficiency1">SR-Comp-1c</a> <br/> $\mathrm{LQ}^\mathrm{u}_{21}$: <a href="155678?version=1&table=Acceptancetimesefficiency9">SR-HM1</a> <a href="155678?version=1&table=Acceptancetimesefficiency10">SR-HM2</a> <a href="155678?version=1&table=Acceptancetimesefficiency11">SR-HM3</a> <a href="155678?version=1&table=Acceptancetimesefficiency12">SR-HM-Disc</a> <br/> $\mathrm{LQ}^\mathrm{u}_{22}$: <a href="155678?version=1&table=Acceptancetimesefficiency13">SR-HM1</a> <a href="155678?version=1&table=Acceptancetimesefficiency14">SR-HM2</a> <a href="155678?version=1&table=Acceptancetimesefficiency15">SR-HM3</a> <a href="155678?version=1&table=Acceptancetimesefficiency16">SR-HM-Disc</a> <br/> $U(1)$ pair (min): <a href="155678?version=1&table=Acceptancetimesefficiency17">SR-HM1</a> <a href="155678?version=1&table=Acceptancetimesefficiency18">SR-HM2</a> <a href="155678?version=1&table=Acceptancetimesefficiency19">SR-HM3</a> <a href="155678?version=1&table=Acceptancetimesefficiency20">SR-HM-Disc</a> <br/> $U(1)$ pair (YM): <a href="155678?version=1&table=Acceptancetimesefficiency21">SR-HM1</a> <a href="155678?version=1&table=Acceptancetimesefficiency22">SR-HM2</a> <a href="155678?version=1&table=Acceptancetimesefficiency23">SR-HM3</a> <a href="155678?version=1&table=Acceptancetimesefficiency24">SR-HM-Disc</a> <br/> </ul> <b>Cutflow:</b> <ul> SUSY benchmarks: <a href="155678?version=1&table=Cutflow5">SR-HM1</a> <a href="155678?version=1&table=Cutflow6">SR-HM2</a> <a href="155678?version=1&table=Cutflow7">SR-HM3</a> <a href="155678?version=1&table=Cutflow8">SR-HM-Disc</a> <a href="155678?version=1&table=Cutflow2">SR-Comp1</a> <a href="155678?version=1&table=Cutflow3">SR-Comp2</a> <a href="155678?version=1&table=Cutflow4">SR-Comp3</a> <a href="155678?version=1&table=Cutflow1">SR-Comp-1c</a> <br/> LQ benchmarks: <a href="155678?version=1&table=Cutflow9">SR-HM1</a> <a href="155678?version=1&table=Cutflow10">SR-HM2</a> <a href="155678?version=1&table=Cutflow11">SR-HM3</a> <a href="155678?version=1&table=Cutflow12">SR-HM-Disc</a> <br/> </ul>
Expected exclusion limit at 95% CL for pair production of top squarks decaying to charm quarks and neutralinos.
Expected exclusion limit $(-1\sigma)$ at 95% CL for pair production of top squarks decaying to charm quarks and neutralinos.
This paper presents a search for supersymmetric particles in models with highly compressed mass spectra, in events consistent with being produced through vector boson fusion. The search uses 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the Large Hadron Collider. Events containing at least two jets with a large gap in pseudorapidity, large missing transverse momentum, and no reconstructed leptons are selected. A boosted decision tree is used to separate events consistent with the production of supersymmetric particles from those due to Standard Model backgrounds. The data are found to be consistent with Standard Model predictions. The results are interpreted using simplified models of $R$-parity-conserving supersymmetry in which the lightest supersymmetric partner is a bino-like neutralino with a mass similar to that of the lightest chargino and second-to-lightest neutralino, both of which are wino-like. Lower limits at 95% confidence level on the masses of next-to-lightest supersymmetric partners in this simplified model are established between 117 and 120 GeV when the lightest supersymmetric partners are within 1 GeV in mass.
Observed and predicted background distributions of the BDT score in $\text{SR}_\text{2j}$ after the exclusion fit. The nominal, pre-fit prediction of an example benchmark signal with $(m(\widetilde{\chi}_{2}^{0}/\widetilde{\chi}_{1}^{\pm}), \widetilde{\chi}_{1}^{0}) = (100, 99)$ GeV is shown in red. The 'Other' category contains rare backgrounds from diboson, triboson and top-quark production processes. The hatched band represents the post-fit experimental, theoretical, and statistical uncertainties in the total background. The bottom panel of each plot shows the ratio between the data and the post-fit background prediction.
Observed and predicted background distributions of the BDT score in $\text{SR}_{\geq3\text{j}}$ after the exclusion fit. The nominal, pre-fit prediction of an example benchmark signal with $(m(\widetilde{\chi}_{2}^{0}/\widetilde{\chi}_{1}^{\pm}), \widetilde{\chi}_{1}^{0}) = (100, 99)$ GeV is shown in red. The 'Other' category contains rare backgrounds from diboson, triboson and top-quark production processes. The hatched band represents the post-fit experimental, theoretical, and statistical uncertainties in the total background. The bottom panel of each plot shows the ratio between the data and the post-fit background prediction.
Expected (dashed black line) and observed (solid red line) 95% CL exclusion limits on the compressed SUSY simplified model with a bino-like LSP and wino-like NLSPs being considered. These are shown with $\pm1\sigma_\text{exp}$ (yellow band) from experimental systematic and statistical uncertainties, and with $\pm1\sigma^{\text{SUSY}}_{\text{theory}}$ (red dotted lines) from signal cross-section uncertainties, respectively. The limits set by the ATLAS searches using the soft lepton signature is illustrated by the blue region while the limit imposed by the LEP experiments is shown in grey.
A search for the production of top-quark pairs with the same electric charge ($tt$ or $\bar{t}\bar{t}$) is presented. The analysis uses proton-proton collision data at $\sqrt{s}=13$ TeV, recorded by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb$^{-1}$. Events with two same-charge leptons and at least two $b$-tagged jets are selected. Neural networks are employed to define two selections sensitive to additional couplings beyond the Standard Model that would enhance the production rate of same-sign top-quark pairs. No significant signal is observed, leading to an upper limit on the total production cross-section of same-sign top-quark pairs of 1.6 fb at 95$\%$ confidence level. Corresponding limits on the three Wilson coefficients associated with the ${\cal O}_{tu}^{(1)}$, ${\cal O}_{Qu}^{(1)}$, and ${\cal O}_{Qu}^{(8)}$ operators in the Standard Model Effective Field Theory framework are derived.
Distributions of the $\mathrm{NN^{SvsB}}$ output for data and the expected background after the likelihood fit in the $SR_{ctu ++}$ signal region. The post-fit background expectations are shown as filled histograms, the combined pre-fit background expectations are shown as dashed lines. The signal distribution using the Wilson coefficient values $c_{tu}^{(1)}=0.04$, $c_{Qu}^{(1)}=0.1$, $c_{Qu}^{(8)}=0.1$ is shown with a dotted line, normalized to the same number of events as the background.
Distributions of the $\mathrm{NN^{SvsB}}$ output for data and the expected background after the likelihood fit in the $SR_{ctu --}$ signal region. The post-fit background expectations are shown as filled histograms, the combined pre-fit background expectations are shown as dashed lines. The signal distribution using the Wilson coefficient values $c_{tu}^{(1)}=0.04$, $c_{Qu}^{(1)}=0.1$, $c_{Qu}^{(8)}=0.1$ is shown with a dotted line, normalized to the same number of events as the background.
Distributions of the $\mathrm{NN^{SvsB}}$ output for data and the expected background after the likelihood fit in the $SR_{cQu ++}$ signal region. The post-fit background expectations are shown as filled histograms, the combined pre-fit background expectations are shown as dashed lines. The signal distribution using the Wilson coefficient values $c_{tu}^{(1)}=0.04$, $c_{Qu}^{(1)}=0.1$, $c_{Qu}^{(8)}=0.1$ is shown with a dotted line, normalized to the same number of events as the background.
Differential measurements of Higgs boson production in the $\tau$-lepton-pair decay channel are presented in the gluon fusion, vector-boson fusion (VBF), $VH$ and $t\bar{t}H$ associated production modes, with particular focus on the VBF production mode. The data used to perform the measurements correspond to 140 fb$^{-1}$ of proton-proton collisions collected by the ATLAS experiment at the LHC. Two methods are used to perform the measurements: the Simplified Template Cross-Section (STXS) approach and an Unfolded Fiducial Differential measurement considering only the VBF phase space. For the STXS measurement, events are categorized by their production mode and kinematic properties such as the Higgs boson's transverse momentum ($p^{\text{H}}_\text{T}$), the number of jets produced in association with the Higgs boson, or the invariant mass of the two leading jets ($m_{jj}$). For the VBF production mode, the ratio of the measured cross-section to the Standard Model prediction for $m_{jj}>1.5$ TeV and $p^{\text{H}}_\text{T}>200$ GeV ($p^{\text{H}}_\text{T}<200$ GeV) is ${1.29}^{+0.39}_{-0.34}$ (${0.12}^{+0.34}_{-0.33}$). This is the first VBF measurement for the higher-$p^{\text{H}}_\text{T}$ criteria, and the most precise for the lower-$p^{\text{H}}_\text{T}$ criteria. The fiducial cross-section measurements, which only consider the kinematic properties of the event, are performed as functions of variables characterizing the VBF topology, such as the signed $\Delta\phi_{jj}$ between the two leading jets. The measurements have a precision of 30%-50% and agree well with the Standard Model predictions. These results are interpreted in the SMEFT framework, and place the strongest constraints to date on the CP-odd Wilson coefficient $c_{H\tilde{W}}$.
Distribution of the reconstructed $\tau\tau$ invariant mass ($m_{\tau\tau}$) for all events in the VBF_0 signal region for $p_{\text{T}}^{H}<200$ GeV. The observed Higgs boson signal corresponds to $(\sigma\times B)/(\sigma\times B)_{\text{SM}}\,=\,0.99$. Entries with values above the $x$-axis range are shown in the last bin of each distribution. The prediction for each sample is determined from the likelihood fit performed to measure the total $pp\rightarrow H\rightarrow\tau\tau$ cross-section.
Distribution of the reconstructed $\tau\tau$ invariant mass ($m_{\tau\tau}$) for all events in the VBF_0 signal region for $p_{\text{T}}^{H}>200$ GeV. The observed Higgs boson signal corresponds to $(\sigma\times B)/(\sigma\times B)_{\text{SM}}\,=\,0.99$. Entries with values above the $x$-axis range are shown in the last bin of each distribution. The prediction for each sample is determined from the likelihood fit performed to measure the total $pp\rightarrow H\rightarrow\tau\tau$ cross-section.
Distribution of the reconstructed $\tau\tau$ invariant mass ($m_{\tau\tau}$) for all events in the VBF_1 signal region for $p_{\text{T}}^{H}<200$ GeV. The observed Higgs boson signal corresponds to $(\sigma\times B)/(\sigma\times B)_{\text{SM}}\,=\,0.99$. Entries with values above the $x$-axis range are shown in the last bin of each distribution. The prediction for each sample is determined from the likelihood fit performed to measure the total $pp\rightarrow H\rightarrow\tau\tau$ cross-section.
A search for long-lived heavy neutral leptons (HNLs) using proton-proton collision data corresponding to an integrated luminosity of 138 fb$^{-1}$ collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC is presented. Events are selected with a charged lepton originating from the primary vertex associated with the proton-proton interaction, as well as a second charged lepton and a hadronic jet associated with a secondary vertex that corresponds to the semileptonic decay of a long-lived HNL. No excess of events above the standard model expectation is observed. Exclusion limits at 95% confidence level are evaluated for HNLs that mix with electron and/or muon neutrinos. Limits are presented in the mass range of 1-16.5 GeV, with excluded square mixing parameter values reaching as low as 2 $\times$ 10$^{-7}$. For masses above 11 GeV, the presented limits exceed all previous results in the semileptonic decay channel, and for some of the considered scenarios are the strongest to date.
The 95% CL limits on $|V_{Ne}|^2$ as a function of the HNL mass for a Majorana HNL. Values of $-1$ indicate that no limit is available for the mass point.
The 95% CL limits on $|V_{N\mu}|^2$ as a function of the HNL mass for a Majorana HNL. Values of $-1$ indicate that no limit is available for the mass point.
The 95% CL limits on mixed coupling as a function of the HNL mass for a Majorana HNL. Values of $-1$ indicate that no limit is available for the mass point.
An analysis of the production of a Higgs boson ($H$) in association with a top quark-antiquark pair ($\mathrm{t\bar{t}}H$) or a single top quark ($tH$) is presented. The Higgs boson decay into a bottom quark-antiquark pair ($H \to\mathrm{b\bar{b}}$) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016-2018, which correspond to an integrated luminosity of 138 fb$^{-1}$. The observed $\mathrm{t\bar{t}}H$ production rate relative to the standard model expectation is 0.33 $\pm$ 0.26 = 0.33 $\pm$ 0.17 (stat) $\pm$ 0.21 (syst). Additionally, the $\mathrm{t\bar{t}}H$ production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of 19.3 $^{+9.2}_{-6.0}$. Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the $\mathrm{t\bar{t}}H$ and $tH$ production rates, and the results are combined with those obtained in other Higgs boson decay channels.
Best fit results of the ttH signal-strength modifier in each channel, in each year, and in the combination of all channels and years. Uncertainties are correlated between the channels and years.
Likelihood-ratio test statistic as a function of the ttH strength modifiers $\mu_{ttH}$ and the $ttB$ background normalisation. The observed best fit point is $(\mu_{ttH}, ttB) = (0.33, 1.19)$.
Best fit results of the ttH signal-strength modifiers in the different Higgs pT bins of the STXS measurement.
The first search for the Z boson decay to $\tau\tau\mu\mu$ at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb$^{-1}$. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the Z $\to$ $\tau\tau\mu\mu$ to Z $\to$ 4$\mu$ branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators.
Distribution of $m_{4\mu}$ after the maximum likelihood fit of the background-only model (stacked histograms) to the data (black points). The nuisance parameters are set to their post-fit values and the signal (black dotted line) is overlaid, scaled to the upper limit on its cross section of 6.9 times the SM expectation. The gray shaded areas in both panels correspond to the total uncertainty in the background prediction. The black vertical bars indicate the statistical uncertainty in the data.
Observed limits at the 95% CL on $C_{\mathrm{LL}}^{2233}$ vs. $C_{\mathrm{LR}}^{2332}$ (red) showing the full range.
Observed limits at the 95% CL on $C_{\mathrm{LR}}^{2233}$ vs. $C_{\mathrm{LL}}^{2332}$ (orange) showing the full range.
A search for the resonant production of a heavy scalar $X$ decaying into a Higgs boson and a new lighter scalar $S$, through the process $X \to S(\to bb) H(\to \gamma\gamma)$, where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using an integrated luminosity of 140 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The search is performed over the mass range 170 $\leq$$m_{X}$$\leq$ 1000 GeV and 15 $\leq$$m_{S}$$\leq$ 500 GeV. Parameterised neural networks are used to enhance the signal purity and to achieve continuous sensitivity in a domain of the ($m_{X}$, $m_{S}$) plane. No significant excess above the expected background is found and 95% CL upper limits are set on the cross section times branching ratio, ranging from 39 fb to 0.09 fb. The largest deviation from the background-only expectation occurs for ($m_{X}$, $m_{S}$) = (575, 200) GeV with a local (global) significance of 3.5 (2.0) standard deviations.
Number of events for the 2 b-jet process category obtained from a background-only fit to data in the signal region and sideband. In the signal region the yield in the most signal-like bin of the PNN distribution, parameterised to the signal point mass (mX, mS) = (250, 100) GeV, is also provided. The uncertainties are symmetrised around the central value. The uncertainty in the total background is calculated taking correlations between the individual contributions into account. For the single Higgs boson processes, 'Other' includes the following production modes: VBF, WH, tHq, and tHW.
Number of events for the 1 b-jet process category obtained from a background-only fit to data in the signal region and sideband. In the signal region the yield in the most signal-like bin of the PNN distribution, parameterised to the signal point mass (mX, mS) = (1000, 70) GeV, is also provided. The uncertainties are symmetrised around the central value. The uncertainty in the total background is calculated taking correlations between the individual contributions into account. For the single Higgs boson processes, 'Other' includes the following production modes: VBF, WH, tHq, and tHW.
Expected and observed 95% CL upper limits on the signal cross section times the branching ratio of X → SH → b b $\gamma \gamma$ shown in the (mX, mS) plane, for each evaluated point. The values of the expected limit one and two standard deviations from the nominal value are also shown. The band at mS = 125 GeV is not included as these signal points are equivalent to those already probed in Phys. Rev. D 106 (2022) 052001.
A search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H $\to$ aa $\to$$\mathrm{b\bar{b}b\bar{b}}$. The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 $\lt$$m_\mathrm{a}$$\lt$ 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp $\to$ WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction $\mathcal{B}$(H $\to$ aa $\to$ $\mathrm{b\bar{b}b\bar{b}}$). The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for $m_\mathrm{a} =$ 20 GeV to 0.36 for $m_\mathrm{a} =$ 60 GeV, complementing other measurements in the $\mu\mu\tau\tau$, $\tau\tau\tau\tau$ and bb$\ell\ell$ ($\ell = $ $\mu$, $\tau$) channels.
Post-fit BDT distributions in the WH channel extracted with the ma = 60 GeV signal hypothesis. Signal regions for the 3b (upper) and 4b (lower) event categories are shown separately for the electron (left) and muon (right) channels. The dotted lines WH20 GeV, WH60 GeV, illustrate the shapes of the signal template normalised to the SM cross section times a branching fraction B(H → aa → bbbb) = 1 and scaled by the factors indicated in the figure. The horizontal error bars indicate the bin width.
Post-fit BDT distributions in the ZH channel extracted with the ma = 60 GeV signal hypothesis. Signal regions for the 3b (upper) and 4b (lower) event categories are shown separately for the electron (left) and muon (right) channels. The dotted lines ZH20 GeV and ZH60 GeV, illustrate the shapes of the signal template normalised to the SM cross section times a branching fraction B(H → aa → bbbb) = 1 and scaled by the factors indicated in the figure. The horizontal error bars indicate the bin width.
Model independent 95% CL upper limits on σ(VH) B(H → aa → bbbb)/σ(SM) for the WH channel (upper), the ZH channel (middle), and the combination of both channels (lower), where “a” is a new pseudoscalar particle decaying through a → bb, and σ(SM) is the SM Higgs boson production cross section.