Searcharxiv⌕ Search

arXiv subjects

CMS Collaboration

Publications and source records attributed to CMS Collaboration.

At least 91 records · Page 5Linked to original sources
arXiv2026

Search for dark matter produced in association with a Higgs boson decaying to bottom quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for dark matter particles produced in association with a Higgs boson decaying to a bottom quark-antiquark pair in proton-proton collisions at $\sqrt{s}$ = 13 TeV is presented. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 101 fb$^{-1}$. The analysis is performed in exclusive categories targeting both Lorentz-boosted (merged) and resolved b jet pair topologies, covering a wide range of Higgs boson transverse momentum. A statistical combination is made with a previous search using data collected in 2016 and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed data agree with the standard model background predictions. Constraints are placed on models predicting new particles or interactions, such as those in the simplified frameworks of baryonic-Z' and 2HDM+a, where the latter is a type-II two-Higgs-doublet model featuring a heavy pseudoscalar with an additional light pseudoscalar. Upper limits at 95% confidence level are set on the production cross section for these models. For the baryonic-Z' model, Z' boson masses below 2.25 TeV are excluded for a dark matter particle candidate mass of 1 GeV. In the 2HDM+a model, heavy pseudoscalar masses between 850 and 1300 GeV are excluded for a light pseudoscalar mass of 350 GeV.

hep-ex↗
arXiv2026

Measurement of the ratio of the B$_\mathrm{c}^+$ $\to$ J/$ψ$$τ^+ν_τ$ and B$_\mathrm{c}^+$ $\to$ J/$ψ$ $μ^+ν_μ$ branching fractions using three-prong $τ$ lepton decays

The ratio between the B$_\mathrm{c}^+$ $\to$ J/$ψ$$τ^+ν_τ$ and B$_\mathrm{c}^+$ $\to$ J/$ψ$$μ^+ν_μ$ branching fractions is measured using a data sample of proton-proton collisions collected by CMS at a center-of-mass energy of 13 TeV in the years 2016$-$2018 and corresponding to an integrated luminosity of 138 fb$^{-1}$. The J$/ψ$ meson is identified through its J$/ψ$ $\to$ $μ^+μ^-$ decay and the tau lepton is reconstructed in the hadronic three-prong final state. The measured ratio of branching fractions in this tau decay mode, $\mathcal{R}^\text{had}_{\mathrm{J}/ψ}$ = 1.04 $_{-0.44}^{+0.50}$, is combined with the previous analysis based on the $τ^+$ $\to$ $μ^+ν_μ\barν_τ$ leptonic decay channel, leading to $\mathcal{R}_{\mathrm{J}/ψ}$ = 0.49 $\pm$ 0.26. As this result is consistent with the standard model prediction of 0.258 $\pm$ 0.004, no evidence of lepton flavor universality violation is found.

hep-ex↗
arXiv2026

Search for a boosted Higgs boson decaying to bottom quark pairs in association with a W or Z boson in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is conducted for standard model Higgs bosons with large transverse momentum ($p_\mathrm{T}$) decaying to bottom quark pairs and produced in association with a hadronically decaying W or Z boson at the LHC. The result is based on a dataset of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector in 2016$-$2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. Boosted Higgs, W, and Z boson decays are reconstructed using large-radius jets with $p_\mathrm{T}$ $\gt$ 450 GeV and identified with heavy-flavor classifiers based on a graph convolutional neural network. The observed signal strength relative to the standard model expectation is $μ$ = 0.72 $^{+0.75}_{-0.71}$ including statistical and systematic uncertainties.

hep-ex↗
arXiv2026

Analysis of the $C\!P$ structure of the Yukawa coupling between the Higgs boson and tau leptons in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV

This paper presents a measurement of the charge-parity ($C\!P$) structure of the Yukawa coupling between the Higgs boson (H) and tau leptons, using proton-proton collision data at $\sqrt{s}$ = 13.6 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 62.4 fb$^{1}$. Angular correlations between the decay products of tau leptons produced in H $\to$ $ττ$ decays are exploited to constrain the effective $C\!P$ mixing angle $α^{\mathrm{H}ττ}$, which parameterizes the admixture of scalar and pseudoscalar couplings. The mixing angle is measured to be $α^{\mathrm{H}ττ}$ = (36$^{+33}_{-30}$)$^\circ$, compared with an expected value of (0 $\pm$ 19)$^\circ$ under the standard model hypothesis. When combined with the previous CMS measurement using data collected at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$, the mixing angle is determined to be (7 $\pm$ 16)$^\circ$, with an expected value of (0 $\pm$ 14)$^\circ$. This result represents the most precise measurement by CMS of the $C\!P$ nature of the Higgs boson coupling to tau leptons, with an expected precision that is the best achieved by any experiment to date.

hep-ex↗
arXiv2026

Search for single production of a vector-like B' quark decaying to a top quark and a W boson in the single-lepton final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is presented for the single production of a narrow-width vector-like B' quark that decays to a t quark and a W boson, with one of the decay products yielding an electron or muon. The data were collected from 2016 to 2018 by the CMS experiment at the LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-2}$. The search is performed in a single-lepton final state, where the B' quark candidate is reconstructed from an electron or muon, missing transverse momentum, one large-radius jet, and one small-radius jet if the t quark decays leptonically. The originating particles of large-radius jets are identified using a neural-network-based tagger, and the dominant background contributions are modeled from data using a neural autoregressive flow network. This search is the most sensitive to date to the single production of narrow-width B' quarks, excluding singlet B' quarks with $Γ/m_\mathrm{B'}$ = 5% for masses between 0.8 and 1.23 TeV. Limits are also placed on the production cross section of single B' quarks produced in association with t quarks, and on the coupling factor of the B' quark to electroweak bosons.

hep-ex↗
arXiv2026

Dependence of two-particle azimuthal correlations on the forward rapidity gap width in pPb collisions at $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV

One of the most striking features of relativistic heavy ion collisions is the presence of collective flow of thousands of produced particles. This flow can be characterized by the Fourier coefficients (${V_{nΔ}}$) of the azimuthal angular distributions of charged particles, and its existence can be explained by the formation of a quark gluon plasma, which behaves as a fluid. Surprisingly, the angular distributions of particles from very small systems such as proton-lead (pPb), proton-proton (pp), electron-positron, and photon-proton ($γ$p) collisions also exhibit non-zero Fourier coefficients, raising the question of whether collective flow is present. This paper presents measurements of $V_{nΔ}$ from a sample of pPb events at $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV that are enriched in photon-lead ($γ$Pb) and pomeron-lead ($\mathrm{\!I\!P}$Pb) interactions by requiring no particles in the proton-going region. Measurements are made as a function of the forward rapidity gap width (the rapidity range in which no particles are found), the transverse momentum of the particles, and the multiplicity of particles in the event. The results are compared to previous measurements of pp, pPb, and $γ$p+$\mathrm{\!I\!P}$p events as well as modern event generators.

nucl-ex↗
arXiv2026

Wasserstein normalized autoencoder for anomaly detection

A novel anomaly detection algorithm is presented. The Wasserstein normalized autoencoder (WNAE) is a normalized probabilistic model that minimizes the Wasserstein distance between the learned probability distribution--a Boltzmann distribution where the energy is the reconstruction error of the autoencoder--and the distribution of the training data. This algorithm has been developed and applied to the identification of semivisible jets--conical sprays of visible standard model particles and invisible dark matter states--with the CMS experiment at the CERN LHC. Trained on jets of particles from simulated standard model processes, the WNAE is shown to learn the probability distribution of the input data in a fully unsupervised fashion, such that it effectively identifies new physics jets as anomalies. The model exhibits stable, convergent training and recovers strong classification performance for a wide range of signals against the selected background process, for which a standard autoencoder fails because of outlier reconstruction. In addition, the model improves upon standard normalized autoencoders while remaining fully agnostic to the signal. The WNAE directly tackles the problem of outlier reconstruction, a common failure mode of autoencoders in anomaly detection tasks.

hep-ex↗
arXiv2026

Search for light scalar particles produced in Higgs boson decays in exclusive final states with two muons and two hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for new scalar particles of $\mathcal{O}$(GeV) mass in exclusive final states with muons and light hadrons is presented. The analysis uses proton-proton collision data produced at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 201$-$2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The search targets exotic decays of the Higgs boson to a pair of prompt or long-lived identical scalar particles with proper decay lengths $cτ$ up to 100 mm and masses within the range of 0.4$-$2.0 GeV. This mass window corresponds to a unique parameter space where hadronic decays of these particles mostly result in a pair of light hadrons. The considered experimental signature is a collimated pair of muons and another pair of charged kaons or pions, each of which may be prompt or displaced. The analysis improves the sensitivity to very light scalar boson masses and demonstrates a novel approach to probe hadronic decays of light scalar bosons. Upper limits on the branching fraction of the Higgs boson to scalar bosons at the level of $\mathcal{O}$(10$^{-4}$) are obtained for several scalar boson masses between 0.4 and 2.0 GeV, with proper decay lengths of up to $\sim$1 mm.

hep-ex↗
arXiv2026

Search for long-lived particles using displaced vertices with low-momentum tracks in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for long-lived particles using final states including a displaced vertex with low-momentum tracks, large missing transverse momentum, and a jet from initial-state radiation is presented. This search uses proton-proton collision data at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2017 and 2018, with a total integrated luminosity of 100 fb$^{-1}$. This analysis adopts specific supersymmetric (SUSY) coannihilation scenarios as benchmark signal models, characterized by a next-to-lightest SUSY particle (NLSP) with a mass difference of less than 25 GeV relative to the lightest SUSY particle, assumed to be a bino-like neutralino. In the top squark ($\tilde{\mathrm{t}}$) NLSP model, the NLSP is a long-lived $\tilde{\mathrm{t}}$, while in the bino-wino NLSP scenario, the mass-degenerate NLSPs are a wino-like long-lived neutralino and a short-lived chargino. The search excludes top squarks with masses less than 400$-$1100 GeV and wino-like neutralinos with masses less than 220$-$550 GeV, depending on the signal parameters, including the mass difference, mass, and lifetime of the long-lived particle. It sets the most stringent limits to date for the $\tilde{\mathrm{t}}$ and bino-wino NLSP models.

hep-ex↗
arXiv2026

Search for heavy long-lived charged particles with level-1 trigger scouting data from proton-proton collisions at $\sqrt{s}$ = 13.6 TeV

A search for heavy long-lived charged particles at the LHC is presented. Particles interacting with the CMS muon detector across several bunch crossings are searched for using a data sample of proton-proton collisions at $\sqrt{s}$ = 13.6 TeV collected with the CMS detector in 2024, corresponding to an integrated luminosity of 3.7 fb$^{-1}$. This is the first search relying on the novel level-1 trigger scouting data set collected without any trigger selection, allowing correlations between bunch crossings to be analyzed. The results are interpreted as upper limits on the cross sections of several benchmark processes with pair production of heavy long-lived charged particles. Upper limits on the fiducial cross section of a heavy long-lived charged particle with $p_\mathrm{T}$ $\gt$ 500 GeV and $\lvertη\rvert$ $\lt$ 0.83 are also set in different ranges of $β=v/c$. This analysis is a crucial proof of concept for the level-1 trigger data scouting system and complements existing searches for heavy long-lived charged particles by extending the sensitivity to lower $β$ values.

hep-ex↗
arXiv2026

Measurement of the Higgs boson total decay width using the H $\to$ WW $\to$ e$νμν$ decay channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The Higgs boson (H) decay width is determined from the ratio of off- and on-shell production of H $\to$ WW $\to$ e$νμν$ using proton-proton collision data corresponding to an integrated luminosity of 138 fb$^{-1}$ collected at $\sqrt{s}$ = 13 TeV by the CMS experiment at the Large Hadron Collider. The off-shell signal strength is measured as $μ_\text{off-shell}$ = 1.2 $^{+0.8}_{-0.7}$. The Higgs boson total decay width is $Γ_\text{H}$ = 3.9 $^{+2.7}_{-2.2}$ MeV, in agreement with the standard model prediction. The uncertainty in this result represents a factor of three improvement over the previous CMS result in this decay channel.

hep-ex↗
arXiv2026

Search for a new heavy scalar resonance decaying to a pair of Z bosons in the four-lepton final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for a new heavy scalar resonance decaying to two Z bosons, each subsequently decaying to a pair of electrons or muons, is presented. The results are based on a proton-proton collision data set collected by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The search is performed over a wide range of resonance masses from 130 GeV to 3 TeV, considering both narrow- and broad-width scenarios, and considering the gluon fusion and vector boson fusion production processes. For the broad-width scenario, the interference between the new resonance, the 125 GeV Higgs boson production, and the continuum background is taken into account. No significant excess with respect to the standard model background expectation is observed in the examined phase space. Upper limits at the 95% confidence level are set on the product of the heavy scalar resonance production cross section and the branching fraction for its decay into two Z bosons. The exclusion limits range from 0.05$-$0.1 pb in the low-mass region to 0.00 pb in the high-mass region.

hep-ex↗
arXiv2026

Exploring small-angle emissions in charm quark jets in proton-proton collisions at $\sqrt{s}$ = 5.02 TeV

A measurement of the angular structure of inclusive jets and those containing a prompt D$^0$ meson in proton-proton collisions at the LHC at a center-of-mass energy of 5.02 TeV is presented. The data corresponding to an integrated luminosity of 301 pb$^{-1}$ were collected by the CMS experiment in 2017. Two jet grooming algorithms, late-$k_\mathrm{T}$ and soft drop, are used to study the intrajet radiation pattern using iterative Cambridge$-$Aachen declustering. The splitting-angle distributions of jets with transverse momentum ($p_\mathrm{T}$) of around 100 GeV, obtained with these two algorithms, show that there is a shift of the distribution for jets containing a prompt D$^0$ meson with respect to inclusive jets. The suppression of emissions at small angles observed in the late-$k_\mathrm{T}$ grooming approach is consistent with the dead-cone effect, whereas the similar suppression for splittings selected with the soft-drop algorithm appears to be induced by gluon splitting to charm quark-antiquark pairs at large angles. The measured distributions are corrected to the particle level and can be used to constrain model predictions for the substructure of high-$p_\mathrm{T}$ charm quark jets.

nucl-ex↗
arXiv2026

Search for the nonresonant and resonant production of a Higgs boson in association with an additional scalar boson in the $γγττ$ final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The results of a search for the production of two scalar bosons in final states with two photons and two tau leptons are presented. The search considers both nonresonant production of a Higgs boson pair, HH, and resonant production via a new boson X which decays either to HH or to H and a new scalar Y. The analysis uses up to 138 fb$^{-1}$ of proton-proton collision data, recorded between 2016 and 2018 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV. No evidence for signal is found in the data. For the nonresonant production, the observed (expected) upper limit at 95% confidence level (CL) on the HH production cross section is set at 930 (740) fb, corresponding to 33 (26) times the standard model prediction. At 95% CL, HH production is observed (expected) to be excluded for values of $κ_λ$ outside the range between $-$12 ($-$9.4) and 17 (15). Observed (expected) upper limits at 95% CL for the X $\to$ HH cross section are found to be within 160 to 2200 (200 to 1800) fb, depending on the mass of X. In the X $\to$ Y($ττ$)H($γγ$) search, the observed (expected) upper limits on the product of the production cross section and decay branching fractions vary between 0.059$-$1.2 fb (0.087$-$0.68 fb). For the X $\to$ Y($γγ$)H($ττ$) search the observed (expected) upper limits on the product of the production cross section and Y $\to$ $γγ$ branching fraction vary between 0.69$-$15 fb (0.73$-$8.3 fb) in the low Y mass search, tightening constraints on the next-to-minimal supersymmetric standard model, and between 0.64$-$10 fb (0.70$-$7.6 fb) in the high Y mass search.

hep-ex↗
arXiv2026

Studies of Z $\to$ 4$\ell$ decays in proton-proton collisions at $\sqrt{s}$ = 8 and 13 TeV

Decays of Z bosons to four charged leptons (electrons and muons) are studied in proton-proton collisions at $\sqrt{s}$ = 8 and 13 TeV. The analysis is based on data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 19.7 fb$^{-1}$ at 8 TeV and 138 fb$^{-1}$ at 13 TeV. The measured value of the inclusive branching fraction for all four-lepton decay modes, $\mathcal{B}$(Z $\to$ 4$\ell$), is [4.67 $\pm$ 0.11 (stat) $\pm$ 0.10 (syst)] $\times$ 10$^{-6}$, which has a precision of about 3% limited by both statistical and systematic uncertainties. Measurements of the individual branching fractions for the decays Z $\to$ 4$μ$, Z $\to$ 4e, and Z $\to$ 2$μ$2e are also reported. Differential decay rates are presented as functions of kinematic and angular quantities in the Z boson rest frame. Measurements of triple-product asymmetries, which are sensitive to possible violations of charge conjugation and parity invariance, are performed for Z $\to$ 4$\ell$ decays. The results are compared with standard model predictions and used to set limits on the production of new gauge bosons.

hep-ex↗
arXiv2026

Search for Higgsinos in final states with low-momentum lepton-track pairs at 13 TeV

We present a search for the pair production of Higgsinos in final states with large missing transverse momentum and either two reconstructed muons or a reconstructed lepton (muon or electron) and an isolated track. The analyzed data correspond to proton-proton collisions with an integrated luminosity of 137 fb$^{-1}$, collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016, 2017, and 2018. The signal scenario assumes four nearly mass degenerate higgsino mass eigenstates, two neutralino states, $\widetildeχ^0_2$ and $\widetildeχ^0_1$, with a small mass difference in the range 1$-$10 GeV and two chargino states $\widetildeχ^\pm_1$ with an intermediate mass. The analysis focuses on the decay of the heavier neutralino into the lighter one and a virtual Z boson, which decays into two same-flavor leptons. The leptons have small transverse momentum and/or a small opening angle between the identified muons. An isolated track is used to recover events in which only one of the two leptons is identified. Multivariate discriminants are used to enhance the sensitivity by efficiently rejecting backgrounds from SM processes or misreconstructed tracks and/or leptons. The search explores a unique phase space and probes a previously unexplored region of the signal model parameter space. Mass differences between the two neutralinos are probed down to 1.5 GeV, assuming a Higgsino mass of 100 GeV. The maximum excluded Higgsino mass is 115 GeV.

hep-ex↗
arXiv2026

Measurement of the dineutrino system kinematic variables in dileptonic top quark pair production in proton-proton collisions at$\sqrt{s}$ = 13 TeV

Differential top quark pair production cross sections are measured in the dilepton final states e$^+$e$^-$, $μ^+μ^-$, and e$^\pmμ^\mp$, as a function of kinematic variables of the two-neutrino system: the transverse momentum $p_\mathrm{T}^{νν}$ of the dineutrino system, the minimum distance in azimuthal angle between $\vec{p}_\mathrm{T}^{\,νν}$ and leptons, and in two dimensions in bins of both observables. The measurements are performed using CERN LHC proton-proton collisions at $\sqrt{s}$ = 13 TeV, recorded by the CMS detector between 2016 and 2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The measured cross sections are unfolded to the particle level using an unregularized least squares method. Results are compared with predictions by the standard model of particle physics, and found to be in agreement with theoretical calculations as well as Monte Carlo simulations.

hep-ex↗
arXiv2026

Search for Higgs boson decays into two neutral scalars with unequal masses in final states with b quarks and tau leptons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for Higgs boson (H) decays into a pair of neutral scalars $ϕ_1$ and $ϕ_2$, with $ϕ_2$ heavier than $ϕ_1$, is performed in final states with b quarks and tau leptons. Depending on the masses of the neutral scalars, $ϕ_2$ can undergo a cascade decay into $ϕ_1ϕ_1$. For both the cascade and non-cascade scenarios, one $ϕ_1$ is required to decay to a pair of tau leptons. Proton-proton collision data corresponding to an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector at the LHC at $\sqrt{s}$ = 13 TeV are analyzed. No statistically significant excess over the standard model expectation is observed. Upper limits are set on the products $σ\mathcal{B}$(H $\to$ $ϕ_1ϕ_2$ $\to$ 3$ϕ_1$ $\to$ 2$τ$4b) and $σ\mathcal{B}$(H $\to$ $ϕ_1ϕ_2$) $\mathcal{B}$($ϕ_1$ $\to$ 2$τ$) $\mathcal{B}$($ϕ_2$ $\to$ 2b) where $σ$ is the Higgs boson production cross section. The observed upper limits range between 0.9 and 36.8 pb at 95% confidence level, depending on the mass hypothesis and decay scenario.

hep-ex↗