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CMS Collaborations

Publications and source records attributed to CMS Collaborations.

10 recordsLinked to original sources
arXiv2026

Combination of ATLAS and CMS searches for Higgs boson pair production at $\sqrt{s} = 13$ TeV

This Letter presents a combination of searches for Higgs boson pair (HH) production performed by the ATLAS and CMS Collaborations using proton-proton collision data sets recorded at $\sqrt{s} = 13$ TeV during the Large Hadron Collider Run 2, corresponding to integrated luminosities ranging between 126 and 140 $\mathrm{fb^{-1}}$. The upper limit at the 95% confidence level on the total HH signal strength, defined as the ratio of the measured cross section to the SM prediction, corresponds to 2.5, with an expected value of 1.7 (2.8) assuming the absence (presence) of the standard model (SM) HH signal. The strength of the HH signal is measured to be $0.8^{+0.9}_{-0.7}$ relative to the SM prediction. The observed significance is found to be 1.1 standard deviations whereas 1.3 are expected for the SM HH signal. Constraints are set on the Higgs boson trilinear self-coupling and on the couplings of two Higgs bosons to two vector bosons, both normalized to the SM predictions and denoted as $\kappa_\lambda$ and $\kappa_{2\mathrm{V}}$, respectively. The observed individual constraints at the 95% confidence level are $-0.71 < \kappa_\lambda < 6.1$ and $0.73 < \kappa_{2\mathrm{V}} < 1.3$, while the expected constraints assuming the presence of the SM HH signal are $-1.3 < \kappa_\lambda < 6.7$ and $0.66 < \kappa_{2\mathrm{V}} < 1.4$.

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arXiv2025

Highlights of the HL-LHC physics projections by ATLAS and CMS

The ATLAS and CMS experiments are unique drivers of our fundamental understanding of nature at the energy frontier. In this contribution to the update of the European Strategy for Particle Physics, we update the physics reach of these experiments at the High-Luminosity LHC (HL-LHC) in a few key areas where they will dominate the state-of-the-art for decades to come.

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arXiv2024

Prompt searches for feebly interacting particles at the LHC

Recent results from the ATLAS and CMS experiments in searches for prompt signatures of feebly interacting particles are presented. All presented results are based on the 2015-2018 data set of $13\,\mathrm{TeV}$ proton-proton collisions, corresponding to an integrated luminosity of about $140\,\mathrm{fb}^{-1}$. The discussed models include dark mesons, heavy neutral leptons, dark matter, and dark photons. The obtained exclusion limits significantly extend the probed parameter space and, in some cases, provide the first collider-based constraints for the considered models.

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arXiv2023

Evidence for the Higgs boson decay to a $Z$ boson and a photon at the LHC

The first evidence for the Higgs boson decay to a $Z$ boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision data sets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb$^{-1}$ for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is $2.2\pm0.7$ times the Standard Model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.

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arXiv2022

Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at $\sqrt{s}= 7$ and 8 TeV

A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and about 20 fb$^{-1}$ at $\sqrt{s}=8$ TeV for each experiment. The combined cross-sections are determined to be $178.5 \pm 4.7$ pb at $\sqrt{s}=7$ TeV and $243.3^{+6.0}_{-5.9}$ pb at $\sqrt{s}=8$ TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be $R_{8/7}= 1.363\pm 0.032$. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are $m_t^\text{pole} = 173.4^{+1.8}_{-2.0}$ GeV and $\alpha_\text{s}(m_Z)= 0.1170^{+ 0.0021}_{-0.0018}$.

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arXiv2019

Combinations of single-top-quark production cross-section measurements and $|f_{\rm LV}V_{tb}|$ determinations at $\sqrt{s}=7$ and 8 TeV with the ATLAS and CMS experiments

This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at $\sqrt{s}=7$ and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb$^{-1}$ at $\sqrt{s}=7$ TeV, and 12.2 to 20.3 fb$^{-1}$ at $\sqrt{s}=8$ TeV. These combinations are performed per centre-of-mass energy and for each production mode: $t$-channel, $tW$, and $s$-channel. The combined $t$-channel cross-sections are $67.5 \pm 5.7$ pb and $87.7 \pm 5.8$ pb at $\sqrt{s}=7$ and 8 TeV respectively. The combined $tW$ cross-sections are $16.3 \pm 4.1$ pb and $23.1 \pm 3.6$ pb at $\sqrt{s}=7$ and 8 TeV respectively. For the $s$-channel cross-section, the combination yields $4.9 \pm 1.4$ pb at $\sqrt{s}=8$ TeV. The square of the magnitude of the CKM matrix element $V_{tb}$ multiplied by a form factor $f_{\rm LV}$is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation $|V_{td}|,|V_{ts}| \ll |V_{tb}|$. All the $|f_{\rm LV}V_{tb}|^2$ determinations, extracted from individual ratios at $\sqrt{s}=7$ and 8 TeV, are combined, resulting in $|f_{\rm LV}V_{tb}|=1.02\pm0.04$ (meas.) $\pm0.02$ (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.

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arXiv2016

Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC $pp$ collision data at $\sqrt{s}=$ 7 and 8 TeV

Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a $W$ or a $Z$ boson or a pair of top quarks, and of the six decay modes $H \to ZZ, WW$, $\gamma\gamma, \tau\tau, bb$, and $\mu\mu$. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton--proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and 20 fb$^{-1}$ at $\sqrt{s} = 8$ TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 $\pm$ 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the $H \to \tau\tau$ decay of $5.4$ and $5.5$ standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.

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arXiv2015

Combined Measurement of the Higgs Boson Mass in $pp$ Collisions at $\sqrt{s}=7$ and 8 TeV with the ATLAS and CMS Experiments

A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the $H \rightarrow \gamma\gamma$ and $H \rightarrow ZZ\rightarrow 4\ell$ decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is $m_{H} = 125.09\pm0.21\,\mathrm{(stat.)}\pm0.11\,\mathrm{(syst.)}~\mathrm{GeV}$.

hep-ex↗
arXiv2008

Discovery potential at the LHC: channels relevant for SM Higgs

The discovery potential of Standard Model Higgs searches at the LHC at 14 TeV center-of-mass energy is reviewed. Decay channels such as $H\toγγ$, $H\to ZZ^{\star}\to 4\ell$, $H\to WW^{\star}$ and $H\to ττ$ are considered. Results are based on the most recent full GEANT-based simulations performed by the ATLAS and CMS experiments.

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