Date

Search for dark matter produced in association with one or two top quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Chekhovsky, Vladimir ; Hayrapetyan, Aram ; Makarenko, Vladimir ; et al.
JHEP 08 (2025) 085, 2025.
Inspire Record 2919645 DOI 10.17182/hepdata.154755

A search is performed for dark matter (DM) produced in association with a single top quark or a pair of top quarks using the data collected with the CMS detector at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to 138 fb$^{-1}$ of integrated luminosity. An excess of events with a large imbalance of transverse momentum is searched for across 0, 1 and 2 lepton final states. Novel multivariate techniques are used to take advantage of the differences in kinematic properties between the two DM production mechanisms. No significant deviations with respect to the standard model predictions are observed. The results are interpreted considering a simplified model in which the mediator is either a scalar or pseudoscalar particle and couples to top quarks and to DM fermions. Axion-like particles that are coupled to top quarks and DM fermions are also considered. Expected exclusion limits of 410 and 380 GeV for scalar and pseudoscalar mediator masses, respectively, are set at the 95% confidence level. A DM particle mass of 1 GeV is assumed, with mediator couplings to fermions and DM particles set to unity. A small signal-like excess is observed in data, with the largest local significance observed to be 1.9 standard deviations for the 150 GeV pseudoscalar mediator hypothesis. Because of this excess, mediator masses are only excluded below 310 (320) GeV for the scalar (pseudoscalar) mediator. The results are also translated into model-independent 95% confidence level upper limits on the visible cross section of DM production in association with top quarks, ranging from 1 pb to 0.02 pb.

57 data tables

The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the 1 b jet, 0 forward jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.

The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the 1 b jet, $\geq 1$ forward jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.

The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the $\geq 2$ b jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.

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Search for new physics in final states with semi-visible jets or anomalous signatures using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
Phys.Rev.D 112 (2025) 012021, 2025.
Inspire Record 2918816 DOI 10.17182/hepdata.159761

A search is presented for hadronic signatures of beyond the Standard Model (BSM) physics, with an emphasis on signatures of a strongly-coupled hidden dark sector accessed via resonant production of a $Z'$ mediator. The ATLAS experiment dataset collected at the Large Hadron Collider from 2015 to 2018 is used, consisting of proton-proton collisions at $\sqrt{s}$ = 13 TeV and corresponding to an integrated luminosity of 140 fb$^{-1}$. The $Z'$ mediator is considered to decay to two dark quarks, which each hadronize and decay to showers containing both dark and Standard Model particles, producing a topology of interacting and non-interacting particles within a jet known as ``semi-visible". Machine learning methods are used to select these dark showers and reject the dominant background of mismeasured multijet events, including an anomaly detection approach to preserve broad sensitivity to a variety of BSM topologies. A resonance search is performed by fitting the transverse mass spectrum based on a functional form background estimation. No significant excess over the expected background is observed. Results are presented as limits on the production cross section of semi-visible jet signals, parameterized by the fraction of invisible particles in the decay and the $Z'$ mass, and by quantifying the significance of any generic Gaussian-shaped mass peak in the anomaly region.

6 data tables

Acceptance times efficiency weighted yields across the signal grid.

The 95% CL limits on the cross-section $\sigma(pp \rightarrow Z' \rightarrow \chi \chi$) times branching ratio B in fb with all statistical and systematic uncertainties, for the $R_{\text{inv}}=$0.2 signal points.

The 95% CL limits on the cross-section $\sigma(pp \rightarrow Z' \rightarrow \chi \chi$) times branching ratio B in fb with all statistical and systematic uncertainties, for the $R_{\text{inv}}=$0.4 signal points.

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Combination and interpretation of differential Higgs boson production cross sections in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Chekhovsky, Vladimir ; Hayrapetyan, Aram ; Makarenko, Vladimir ; et al.
CMS-HIG-23-013, 2025.
Inspire Record 2913615 DOI 10.17182/hepdata.156816

Precision measurements of Higgs boson differential production cross sections are a key tool to probe the properties of the Higgs boson and test the standard model. New physics can affect both Higgs boson production and decay, leading to deviations from the distributions that are expected in the standard model. In this paper, combined measurements of differential spectra in a fiducial region matching the experimental selections are performed, based on analyses of four Higgs boson decay channels ($\gamma\gamma$, ZZ$^{(*)}$, WW$^{(*)}$, and $\tau\tau$) using proton-proton collision data recorded with the CMS detector at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The differential measurements are extrapolated to the full phase space and combined to provide the differential spectra. A measurement of the total Higgs boson production cross section is also performed using the $\gamma\gamma$ and ZZ decay channels, with a result of 53.4$^{+2.9}_{-2.9}$ (stat)$^{+1.9}_{-1.8}$ (syst) pb, consistent with the standard model prediction of 55.6 $\pm$ 2.5 pb. The fiducial measurements are used to compute limits on Higgs boson couplings using the $\kappa$-framework and the SM effective field theory.

17 data tables

Observed best fit differential cross section for the $p_{T}^{H}$ observable

Observed best fit differential cross section for the $N_{jets}$ observable

Observed best fit differential cross section for the $p_{T}^{j1}$ (GeV) observable

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Search for charged-lepton flavour violation in top quark interactions with an up-type quark, a muon, and a $\tau$ lepton in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
CMS-TOP-22-011, 2025.
Inspire Record 2911292 DOI 10.17182/hepdata.153300

A search for charged-lepton flavour violation (CLFV) in top quark (t) production and decay is presented. The search uses proton-proton collision data corresponding to 138 fb$^{-1}$ collected with the CMS experiment at $\sqrt{s}$ = 13 TeV. The signal consists of the production of a single top quark via a CLFV interaction or top quark pair production followed by a CLFV decay. The analysis selects events containing a pair of oppositely charged muon and hadronically decaying $\tau$ lepton and at least three jets, where one has been identified to originate from the fragmentation of a bottom quark. Machine learning classification techniques are used to distinguish signal from standard model background events. The results of this search are consistent with the standard model expectations. The upper limits at 95% confidence level on the branching fraction $\mathcal{B}$ for CLFV top quark decays to a muon, a $\tau$ lepton, and an up or a charm quark are set at $\mathcal{B}$(t $\to \mu\tau$u) $\lt$ (0.040, 0.078, and 0.118) $\times$ 10$^{-6}$, and $\mathcal{B}$(t $\to\mu\tau$c) $\lt$ (0.810, 1.710, and 2.052) $\times$ 10$^{-6}$ for scalar, vector, and tensor-like operators, respectively.

2 data tables

The expected and observed upper limits on CLFV Wilson coefficients. The Limits on the Wilson coefficients are extracted from the upper limits on the cross sections.

The expected and observed upper limits on top quark CLFV branching fractions. The Limits on the top quark CLFV branching fractions are extracted from the upper limits on the Wilson coefficients.


Evidence for the collective nature of radial flow in Pb+Pb collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
CERN-EP-2025-068, 2025.
Inspire Record 2907010 DOI 10.17182/hepdata.158359

Anisotropic flow and radial flow are two key probes of the expansion dynamics and properties of the quark-gluon plasma (QGP). While anisotropic flow has been extensively studied, radial flow, which governs the system's radial expansion, has received less attention. Notably, experimental evidence for the global and collective nature of radial flow has been lacking. This Letter presents the first measurement of transverse momentum ($p_{\mathrm{T}}$) dependence of radial flow fluctuations ($v_0(p_{\mathrm{T}})$) over $0.5<p_{\mathrm{T}}<10$ GeV, using a two-particle correlation method in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The data reveal three key features supporting the collective nature of radial flow: long-range correlation in pseudorapidity, factorization in $p_{\mathrm{T}}$, and centrality-independent shape in $p_{\mathrm{T}}$. The comparison with a hydrodynamic model demonstrates the sensitivity of $v_0(p_{\mathrm{T}})$ to bulk viscosity, a crucial transport property of the QGP. These findings establish a new, powerful tool for probing collective dynamics and properties of the QGP.

99 data tables

Data from Figure 2, panel a, $v_{0}$

Data from Figure 2, panel c, upper panel, Normalized Covariance $\times 10^{3}$ in 0-5% Centrality

Data from Figure 2, panel c, lower panel, Normalized Covariance $\times 10^{3}$ in 50-60% Centrality

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Search for electroweak production of vector-like leptons in $\tau$-lepton and $b$-jet final states in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
Eur.Phys.J.C 85 (2025) 1335, 2025.
Inspire Record 2905977 DOI 10.17182/hepdata.158820

A search for pair-production of vector-like leptons is presented, considering their decays into a third-generation Standard Model (SM) quark and a vector leptoquark ($U_1$) as predicted by an ultraviolet-complete extension of the SM, referred to as the '4321' model. Given the assumed decay of $U_1$ into third-generation SM fermions, the final state can contain multiple $\tau$-leptons and $b$-quarks. This search is based on a dataset of $pp$ collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of up to 140 fb$^{-1}$. No significant excess above the SM background prediction is observed, and 95% confidence level limits on the cross-section times branching ratio are derived as a function of the vector-like lepton mass. A lower observed (expected) limit of 910 GeV (970 GeV) is set on the vector-like lepton mass. Additionally, the results are interpreted for a supersymmetric model with an $R$-parity violating coupling to the third-generation quarks and leptons. Lower observed (expected) limits are obtained on the higgsino mass at 880 GeV (940 GeV) and on the wino mass at 1170 GeV (1170 GeV).

8 data tables

Observed (solid line with markers) and expected (dashed line) 95&percnt; CL upper limits on the VLL pair production cross-section (&sigma;<sub>VLL</sub>) times branching ratio (BR) to third generation quarks and leptons as a function of m<sub>VLL</sub>. The limits presented in black lines are obtained after combining all five signal regions. The inner green (outer yellow) band corresponds to the &plusmn;1 &sigma; (&plusmn;2 &sigma;) uncertainty around the combined expected limit. The 95&percnt; CL expected upper limits in the three individual channels (1&tau;<sub>had</sub> &ge;3b MST, 1&tau;<sub>had</sub> &ge;3b BJET and &ge;2&tau;<sub>had</sub> &ge;3b MSDT) are shown for comparison. The solid red line represents the theory prediction of the VLL pair production cross-section at NLO in QCD.

Observed (solid line with markers) and expected (dashed line) 95&percnt; CL upper limits on the higgsino pair production cross-section (&sigma;<sub>higgsino</sub>) times branching ratio (BR) to third generation quarks and leptons as a function of m<sub>higgsino</sub>. The limits presented in black lines are obtained after combining all five signal regions. The inner green (outer yellow) band corresponds to the &plusmn;1 &sigma; (&plusmn;2 &sigma;) uncertainty around the combined expected limit. The 95&percnt; CL expected upper limits in the three individual channels (1&tau;<sub>had</sub> &ge;3b MST, 1&tau;<sub>had</sub> &ge;3b BJET and &ge;2&tau;<sub>had</sub> &ge;3b MSDT) are shown for comparison. The solid red line represents the theory prediction of the higgsino pair production cross-section at NLO in QCD.

Observed (solid line with markers) and expected (dashed line) 95&percnt; CL upper limits on the wino pair production cross-section (&sigma;<sub>wino</sub>) times branching ratio (BR) to third generation quarks and leptons as a function of m<sub>wino</sub>. The limits presented in black lines are obtained after combining all five signal regions. The surrounding inner green (outer yellow) band corresponds to the &plusmn;1 &sigma; (&plusmn;2 &sigma;) uncertainty around the combined expected limit. The 95&percnt; CL expected upper limits in the three individual channels (1&tau;<sub>had</sub> &ge;3b MST, 1&tau;<sub>had</sub> &ge;3b BJET and &ge;2&tau;<sub>had</sub> &ge;3b MSDT) are shown for comparison. The solid red line represents the theory prediction of the wino pair production cross-section at NLO in QCD.

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Search for events with one displaced vertex from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in $pp$ collisions at $\sqrt{s}=13$ TeV

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
Phys.Rev.D 112 (2025) 092001, 2025.
Inspire Record 2905251 DOI 10.17182/hepdata.158373

A search for events with one displaced vertex from long-lived particles using data collected by the ATLAS detector at the Large Hadron Collider is presented, using 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 13$ TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of long-lived particles decaying into hadronic jets in the muon spectrometer displaced between 3 m and 14 m from the primary interaction vertex. The observed number of events is consistent with the expected background and limits for several benchmark signals are determined. A scalar-portal model and a Higgs-boson-portal baryogenesis model are considered. A dedicated analysis channel is employed to target Z-boson associated long-lived particle production, including an axion-like particle and a dark photon model. For the Higgs boson model, branching fractions above 1% are excluded at 95% confidence level for long-lived particle proper decay lengths ranging from 5 cm to 40 m. For the photo-phobic axion-like particle model considered, this search produces the strongest limits to date for proper decay lengths greater than $\mathcal{O}(10)$ cm.

309 data tables

Summary of the one-DV limits for the H/ϕ arrow ss model. Comparison between observed and expected 95% CL limits on (σ/σggH)×B for an SM-like Higgs boson portal mediator and ms=35 GeV. The observed limits are consistent with the expected ones within the uncertainties.

Observed 95% CL limits on (σ/σggH)×B for all Higgs boson portal mediator samples where the cross-section is normalized to the SM Higgs boson gluon–gluon fusion production cross-section, σggH = 48.61 pb [97]. The observed limits are consistent with the expected ones within the uncertainties.

Observed 95% CL limits on σ×B for mϕ≠ 125 GeV. The observed limits are consistent with the expected ones within the uncertainties.

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Version 2
Search for $t$-channel scalar and vector leptoquark exchange in the high-mass dimuon and dielectron spectra in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
CMS-EXO-22-013, 2025.
Inspire Record 2904423 DOI 10.17182/hepdata.156848

A search for $t$-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb$^{-1}$. Eight scenarios are considered, in which scalar or vector LQs couple up or down quarks to muons or electrons, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1-5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.

26 data tables

Observed and Expected UL exclusions on the $BR(H\to SUEP)$ of hadronic signals with $m_{A'} = 0.7\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.15$ and $BR(A' \rightarrow \pi\pi) = 0.7$.

The observed data in the dielectron channel and the fitted signal-plus-background templates, shown for the $S_{e u}$ scenario with a candidate LQ mass of 2.5 TeV. Distributions of events are binned in the reconstructed dilepton mass, rapidity, and cosine theta.

Observed and Expected UL exclusions on the $BR(H\to S)$ of leptonic signals with $m_{A'} = 0.5\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.2$ and $BR(A' \rightarrow \pi\pi) = 0.6$.

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Search for dark matter production in association with a single top quark in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Chekhovsky, Vladimir ; Hayrapetyan, Aram ; Makarenko, Vladimir ; et al.
CMS-SUS-23-004, 2025.
Inspire Record 2904618 DOI 10.17182/hepdata.156969

A search for the production of a single top quark in association with invisible particles is performed using proton-proton collision data collected with the CMS detector at the LHC at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. In this search, a flavor-changing neutral current produces a single top quark or antiquark and an invisible state nonresonantly. The invisible state consists of a hypothetical spin-1 particle acting as a new mediator and decaying to two spin-1/2 dark matter candidates. The analysis searches for events in which the top quark or antiquark decays hadronically. No significant excess of events compatible with that signature is observed. Exclusion limits at 95% confidence level are placed on the masses of the spin-1 mediator and the dark matter candidates, and are compared to constraints from the dark matter relic density measurements. In a vector (axial-vector) coupling scenario, masses of the spin-1 mediator are excluded up to 1.85 (1.85) TeV with an expectation of 2.0 (2.0) TeV, whereas masses of the dark matter candidates are excluded up to 0.75 (0.55) TeV with an expectation of 0.85 (0.65) TeV.

21 data tables

Prefit distribution of the magnitude of the hadronic recoil $R_{\mathrm{T}}$ in the SR. The last bin of the distribution also contains events with $R_{\mathrm{T}}$ > 1000 GeV. The distributions of background processes stem from simulation and are stacked together. A representative mono-top signal (vector coupling scenario) with a mediator mass of 1 TeV, a DM candidate mass of 150 GeV, and a cross section of 1 pb is overlaid as an orange line. The gray band represents the statistical and unconstrained systematic uncertainties in the simulated event yields.

Prefit distributions of the magnitude of the hadronic recoil $R_{\mathrm{T}}$ in the SR (t-pass) and SR (t-fail). The last bin of each distribution also contains events with $R_{\mathrm{T}}$ > 1000 GeV. The distributions of background processes stem from simulation and are stacked together. A representative mono-top signal (vector coupling scenario) with a mediator mass of 1 TeV, a DM candidate mass of 150 GeV, and a cross section of 1 pb is overlaid as an orange line. The gray band represents the statistical and unconstrained systematic uncertainties in the simulated event yields.

Prefit distributions of the magnitude of the hadronic recoil $R_{\mathrm{T}}$ in the SR (t-pass) and SR (t-fail). The last bin of each distribution also contains events with $R_{\mathrm{T}}$ > 1000 GeV. The distributions of background processes stem from simulation and are stacked together. A representative mono-top signal (vector coupling scenario) with a mediator mass of 1 TeV, a DM candidate mass of 150 GeV, and a cross section of 1 pb is overlaid as an orange line. The gray band represents the statistical and unconstrained systematic uncertainties in the simulated event yields.

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Measurements of the production cross-sections of a Higgs boson in association with a vector boson and decaying into $WW^\ast$ with the ATLAS detector at $\sqrt{s} = 13$ TeV

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
JHEP 08 (2025) 034, 2025.
Inspire Record 2905253 DOI 10.17182/hepdata.157861

Measurements of the total and differential Higgs boson production cross-sections, via $WH$ and $ZH$ associated production using $H\rightarrow WW^\ast\rightarrow\ellν\ellν$ and $H\rightarrow WW^\ast\rightarrow\ellνjj$ decays, are presented. The analysis uses proton-proton events delivered by the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector between 2015 and 2018. The data correspond to an integrated luminosity of 140 fb$^{-1}$. The sum of the $WH$ and $ZH$ cross-sections times the $H\rightarrow WW^\ast$ branching fraction is measured to be $0.44^{+0.10}_{-0.09}$ (stat.) $^{+0.06}_{-0.05}$ (syst.) pb, in agreement with the Standard Model prediction. Higgs boson production is further characterised through measurements of the differential cross-section as a function of the transverse momentum of the vector boson and in the framework of Simplified Template Cross-Sections.

12 data tables

Post-fit distribution of $ANN_{Zdom}$ in the Z-dominated SR. The post-fit result is obtained from the combined 2-POI fit described in section 9.1 of the paper.

Best-fit values of the total $WH$, $ZH$, and $VH$ cross sections times the $H\rightarrow WW^{*}$ branching ratio.

Observed profile likelihood as a function of $\sigma\times\mathcal{B}_{H\rightarrow WW^{*}}$ normalised by the SM expectation for the $VH$ and $WH/ZH$ measurements from the combined 1- and 2-POI fits, respectively

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