Date

Combination of measurements of the top quark mass from data collected by the ATLAS and CMS experiments at $\sqrt{s}=7$ and 8 TeV

The ATLAS & CMS collaborations Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 132 (2024) 261902, 2024.
Inspire Record 2789110 DOI 10.17182/hepdata.143309

A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The data sets used correspond to an integrated luminosity of up to 5 and 20$^{-1}$ of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak $t$-channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is $m_\mathrm{t}$ = 172.52 $\pm$ 0.14 (stat) $\pm$ 0.30 (syst) GeV, with a total uncertainty of 0.33 GeV.

1 data table

Uncertainties on the $m_{t}$ values extracted in the LHC, ATLAS, and CMS combinations arising from the categories described in the text, sorted in order of decreasing value of the combined LHC uncertainty.


Differential cross section measurements for the production of top quark pairs and of additional jets using dilepton events from pp collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Tumasyan, Armen ; Adam, Wolfgang ; Andrejkovic, Janik Walter ; et al.
JHEP 02 (2025) 064, 2025.
Inspire Record 2758138 DOI 10.17182/hepdata.127702

Differential cross sections for top quark pair ($\mathrm{t\bar{t}}$) production are measured in proton-proton collisions at a center-of-mass energy of 13 TeV using a sample of events containing two oppositely charged leptons. The data were recorded with the CMS detector at the CERN Large Hadron Collider and correspond to an integrated luminosity of 138 fb$^{-1}$. The differential cross sections are measured as functions of kinematic observables of the $\mathrm{t\bar{t}}$ system, the top quark and antiquark and their decay products, as well as of the number of additional jets in the event. The results are presented as functions of up to three variables and are corrected to the parton and particle levels. When compared to standard model predictions based on quantum chromodynamics at different levels of accuracy, it is found that the calculations do not always describe the observed data. The deviations are found to be largest for the multi-differential cross sections.

4 data tables

Absolute differential ttbar production cross section measured as function of top pT at the parton level in the full phase space.

Absolute differential ttbar production cross section measured as function of top rapidity at the parton level in the full phase space.

Absolute differential ttbar production cross section measured as function of ttbar mass at the parton level in the full phase space.

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New constraints on ultraheavy dark matter from the LZ experiment

The LZ collaboration Aalbers, J. ; Akerib, D.S. ; Al Musalhi, A.K. ; et al.
Phys.Rev.D 109 (2024) 112010, 2024.
Inspire Record 2758452 DOI 10.17182/hepdata.151392

Searches for dark matter with liquid xenon time projection chamber experiments have traditionally focused on the region of the parameter space that is characteristic of weakly interacting massive particles, ranging from a few GeV/$c^2$ to a few TeV/$c^2$. Models of dark matter with a mass much heavier than this are well motivated by early production mechanisms different from the standard thermal freeze-out, but they have generally been less explored experimentally. In this work, we present a re-analysis of the first science run (SR1) of the LZ experiment, with an exposure of $0.9$ tonne$\times$year, to search for ultraheavy particle dark matter. The signal topology consists of multiple energy deposits in the active region of the detector forming a straight line, from which the velocity of the incoming particle can be reconstructed on an event-by-event basis. Zero events with this topology were observed after applying the data selection calibrated on a simulated sample of signal-like events. New experimental constraints are derived, which rule out previously unexplored regions of the dark matter parameter space of spin-independent interactions beyond a mass of 10$^{17}$ GeV/$c^2$.

5 data tables

Upper limit on the WIMP-nucleon scattering cross section from the multiple-scatter analysis.

Upper limit on the WIMP-nucleus scattering cross section from the multiple-scatter analysis.

Upper limit on the WIMP-nucleon scattering cross section from the single-scatter analysis.

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Search for pair production of scalar and vector leptoquarks decaying to muons and bottom quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 109 (2024) 112003, 2024.
Inspire Record 2758137 DOI 10.17182/hepdata.146074

A search for pair production of scalar and vector leptoquarks (LQs) each decaying to a muon and a bottom quark is performed using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. No excess above standard model expectation is observed. Scalar (vector) LQs with masses less than 1810 (2120) GeV are excluded at 95% confidence level, assuming a 100% branching fraction of the LQ decaying to a muon and a bottom quark. These limits represent the most stringent to date.

11 data tables

Comparison of data and background pT distribution at the preselection level for the first leading muon.

Comparison of data and background pT distribution at the preselection level for the second leading muon.

Comparison of data and background pT distribution at the preselection level for the first leading jet.

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CIRCUS: an autonomous control system for antimatter, atomic and quantum physics experiments

The AEgIS collaboration Volponi, M. ; Huck, S. ; Caravita, R. ; et al.
EPJ Quant.Technol. 11 (2024) 10, 2024.
Inspire Record 2756315 DOI 10.17182/hepdata.156992

A powerful and robust control system is a crucial, often neglected, pillar of any modern, complex physics experiment that requires the management of a multitude of different devices and their precise time synchronisation. The AEgIS collaboration presents CIRCUS, a novel, autonomous control system optimised for time-critical experiments such as those at CERN's Antiproton Decelerator and, more broadly, in atomic and quantum physics research. Its setup is based on Sinara/ARTIQ and TALOS, integrating the ALPACA analysis pipeline, the last two developed entirely in AEgIS. It is suitable for strict synchronicity requirements and repeatable, automated operation of experiments, culminating in autonomous parameter optimisation via feedback from real-time data analysis. CIRCUS has been successfully deployed and tested in AEgIS; being experiment-agnostic and released open-source, other experiments can leverage its capabilities.

6 data tables

Synchronous voltage ramp-up to 20 V on three high-voltage amplifier channels 10 μs subsequent to the arrival of a common trigger pulse at zero time in the figure. The inset shows a zoom to the shoulder region for a better visualisation of the synchronicity.

A feedback loop uses the uncorrected laser pulse timings (red squares) to calculate the deviation from the user setting (solid black line) over the course of an hour, and corrects the timing of the subsequent desired laser pulse that is used for the actual experiment (blue circles). Independent of short-term to long-term drifts or even sudden jumps, the resulting timing is always close to the desired value.

A feedback loop uses the uncorrected laser pulse timings (red squares) to calculate the deviation from the user setting (solid black line) over the course of an hour, and corrects the timing of the subsequent desired laser pulse that is used for the actual experiment (blue circles). Independent of short-term to long-term drifts or even sudden jumps, the resulting timing is always close to the desired value.

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Combined search for electroweak production of winos, binos, higgsinos, and sleptons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 109 (2024) 112001, 2024.
Inspire Record 2755433 DOI 10.17182/hepdata.145859

A combination of the results of several searches for the electroweak production of the supersymmetric partners of standard model bosons, and of charged leptons, is presented. All searches use proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC in 2016-2018. The analyzed data correspond to an integrated luminosity of up to 137 fb$^{-1}$. The results are interpreted in terms of simplified models of supersymmetry. Two new interpretations are added with this combination: a model spectrum with the bino as the lightest supersymmetric particle together with mass-degenerate higgsinos decaying to the bino and a standard model boson, and the compressed-spectrum region of a previously studied model of slepton pair production. Improved analysis techniques are employed to optimize sensitivity for the compressed spectra in the wino and slepton pair production models. The results are consistent with expectations from the standard model. The combination provides a more comprehensive coverage of the model parameter space than the individual searches, extending the exclusion by up to 125 GeV, and also targets some of the intermediate gaps in the mass coverage.

28 data tables

Post-fit distribution of the $M(ll)$ variable for the low-$p_{\mathrm{T}}^{\mathrm{miss}}$ bins in the '2l soft' signal region of the '2/3l soft' analysis.

Post-fit distribution of the $M(ll)$ variable for the medium-$p_{\mathrm{T}}^{\mathrm{miss}}$ bins in the '2l soft' signal region of the '2/3l soft' analysis.

Post-fit distribution of the $M(ll)$ variable for the high-$p_{\mathrm{T}}^{\mathrm{miss}}$ bins in the '2l soft' signal region of the '2/3l soft' analysis.

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Version 2
Search for long-lived particles decaying in the CMS muon detectors in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 110 (2024) 032007, 2024.
Inspire Record 2755637 DOI 10.17182/hepdata.146645

A search for long-lived particles (LLPs) decaying in the CMS muon detectors is presented. A data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded at the LHC in 2016-2018, is used. The decays of LLPs are reconstructed as high multiplicity clusters of hits in the muon detectors. In the context of twin Higgs models, the search is sensitive to LLP masses from 0.4 to 55 GeV and a broad range of LLP decay modes, including decays to hadrons, $\tau$ leptons, electrons, or photons. No excess of events above the standard model background is observed. The most stringent limits to date from LHC data are set on the branching fraction of the Higgs boson decay to a pair of LLPs with masses below 10 GeV. This search also provides the best limits for various intervals of LLP proper decay length and mass. Finally, this search sets the first limits at the LHC on a dark quantum chromodynamic sector whose particles couple to the Higgs boson through gluon, Higgs boson, photon, vector, and dark-photon portals, and is sensitive to branching fractions of the Higgs boson to dark quarks as low as 2 $\times$ 10$^{-3}$.

106 data tables

The cluster reconstruction efficiency, including both DT and CSC clusters, as a function of the simulated r and |z| decay positions of the particle S decaying to $d\bar{d}$ in events with $\it{p}_{T}^\text{miss} >$ 200 GeV, for a mass of 40 GeV and a range of c$\tau$ values uniformly distributed between 1 and 10 m.

The DT cluster reconstruction efficiency as a function of the simulated r decay positions of S decaying to $d\bar{d}$ in events with $\it{p}_{T}^\text{miss} >$ 200 GeV, for a mass of 40 GeV and a range of c$\tau$ values between 1 and 10 m. The clusters are selected from signal events satisfying the $\it{p}_{T}^\text{miss} >$ 200 GeV requirement.

The CSC cluster reconstruction efficiency as a function of the simulated |z| decay positions of S decaying to $d\bar{d}$ in events with $\it{p}_{T}^\text{miss} >$ 200 GeV, for a mass of 40 GeV and a range of c$\tau$ values between 1 and 10 m. The clusters are selected from signal events satisfying the $\it{p}_{T}^\text{miss} >$ 200 GeV requirement.

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ATLAS Run 2 searches for electroweak production of supersymmetric particles interpreted within the pMSSM

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abeling, Kira ; et al.
JHEP 05 (2024) 106, 2024.
Inspire Record 2755168 DOI 10.17182/hepdata.149493

A summary of the constraints from searches performed by the ATLAS Collaboration for the electroweak production of charginos and neutralinos is presented. Results from eight separate ATLAS searches are considered, each using 140 fb$^{-1}$ of proton-proton data at a centre-of-mass energy of $\sqrt{s}$=13 TeV collected at the Large Hadron Collider during its second data-taking run. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, where R-parity conservation is assumed and the lightest supersymmetric particle is assumed to be the lightest neutralino. Constraints from previous electroweak, flavour and dark matter related measurements are also considered. The results are presented in terms of constraints on supersymmetric particle masses and are compared with limits from simplified models. Also shown is the impact of ATLAS searches on parameters such as the dark matter relic density and the spin-dependent and spin-independent scattering cross-sections targeted by direct dark matter detection experiments. The Higgs boson and Z boson `funnel regions', where a low-mass neutralino would not oversaturate the dark matter relic abundance, are almost completely excluded by the considered constraints. Example spectra for non-excluded supersymmetric models with light charginos and neutralinos are also presented.

2 data tables

SLHA files and exclusion information (in CSV format) are available to download for the pMSSM models in this paper. Please refer to <a href="https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2020-15/inputs/ATLAS_EW_pMSSM_Run2.html">this web page</a> for download links along with a description of the contents.

SLHA files and exclusion information (in CSV format) are available to download for the pMSSM models in this paper. Please refer to <a href="https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2020-15/inputs/ATLAS_EW_pMSSM_Run2.html">this web page</a> for download links along with a description of the contents.


Search for electroweak production of supersymmetric particles in final states with two $\tau$-leptons in $\sqrt{s}$ = 13 TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abeling, Kira ; et al.
JHEP 05 (2024) 150, 2024.
Inspire Record 2754043 DOI 10.17182/hepdata.145758

Three searches for the direct production of $\tau$-sleptons or charginos and neutralinos in final states with at least two hadronically decaying $\tau$-leptons are presented. For chargino and neutralino production, decays via intermediate $\tau$-sleptons or $W$ and $h$ bosons are considered. The analysis uses a dataset of $pp$ collisions corresponding to an integrated luminosity of $139\,$fb$^{-1}$, recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed and supersymmetric particle mass limits at 95% confidence level are obtained in simplified models. For direct production of $\tilde~{\chi}^+_1\tilde~{\chi}^-_1$, chargino masses are excluded up to 970 GeV, while $\tilde~{\chi}^{\pm}_1$ and $\tilde~{\chi}^0_2$ masses up to 1160 GeV (330 GeV) are excluded for $\tilde~{\chi}^{\pm}_1\tilde~{\chi}^0_2$/$\tilde~{\chi}^+_1\tilde~{\chi}^-_1$ production with subsequent decays via $\tau$-sleptons ($W$ and $h$ bosons). Masses of $\tau$-sleptons up to 500 GeV are excluded for mass degenerate $\tilde~{\tau}_{L,R}$ scenarios and up to 425 GeV for $\tilde~{\tau}_L$-only scenarios. Sensitivity to $\tilde~{\tau}_R$-only scenarios from the ATLAS experiment is presented here for the first time, with $\tilde~{\tau}_R$ masses excluded up to 350 GeV.

89 data tables

The post-fit BDT score distribution for the direct stau channel, showing the scores for BDT1, before the selections on the BDT score is made. The black arrow depicts the BDT score selection for the SR-BDT. A few example SUSY scenarios targeted by each BDT are overlaid for illustration.

The post-fit BDT score distribution for the direct stau channel, showing the scores for BDT2, before the selections on the BDT score is made. The black arrow depicts the BDT score selection for the SR-BDT. A few example SUSY scenarios targeted by each BDT are overlaid for illustration.

The post-fit BDT score distribution for the direct stau channel, showing the scores for BDT3, before the selections on the BDT score is made. The black arrow depicts the BDT score selection for the SR-BDT. A few example SUSY scenarios targeted by each BDT are overlaid for illustration.

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Observation of the $\Lambda_\text{b}^0\to J/\psi\Xi^-K^+$ decay

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 84 (2024) 1062, 2024.
Inspire Record 2752469 DOI 10.17182/hepdata.145642

Using proton-proton collision data corresponding to an integrated luminosity of 140 fb$^{-1}$ collected by the CMS experiment at $\sqrt{s}$ = 13 TeV, the $\Lambda_\text{b}^0$$\to$ J/$\psi\Xi^-$K$^+$ decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the $\Lambda_\text{b}^0$$\to$$\psi$(2S)$\Lambda$ decay, is measured to be $\mathcal{B}$($\Lambda_\text{b}^0$$\to$ J/$\psi\Xi^-$K$^+$) / $\mathcal{B}$( $\Lambda_\text{b}^0$$\to$$\psi$(2S)$\Lambda$) = [3.38 $\pm$ 1.02 $\pm$ 0.61 $\pm$ 0.03]%, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in $\mathcal{B}$($\psi$(2S) $\to$ J/$\psi\pi^+\pi^-$) and $\mathcal{B}$($\Xi^-$ $\to$ $\Lambda\pi^-$).

1 data table

The measured branching fraction ratio