Search for heavy neutral resonances decaying to tau lepton pairs in proton-proton collisions at (Formula presented)

A search for heavy neutral gauge bosons ((Formula presented)) decaying into a pair of tau leptons is performed in proton-proton collisions at (Formula presented) at the CERN LHC. The data were collected with the CMS detector and correspond to an integrated luminosity of (Formula presented). The observations are found to be in agreement with the expectation from standard model processes. Limits at 95% confidence level are set on the product of the (Formula presented) production cross section and its branching fraction to tau lepton pairs for a range of (Formula presented) boson masses. For a narrow resonance in the sequential standard model scenario, a (Formula presented) boson with a mass below 3.5 TeV is excluded. This is the most stringent limit to date from this type of search

Search for rare decays of the Z and Higgs bosons to a J/ψ or ψ(2S) meson and a photon in proton-proton collisions at s=13TeV

A search is presented for rare decays of the Image 1 and Higgs bosons to a photon and a Image 2 or a Image 3 meson, with the charmonium state subsequentially decaying to a pair of muons. The data set corresponds to an integrated luminosity of 123fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. No evidence for branching fractions of these rare decay channels larger than predicted in the standard model is observed. Upper limits at 95% confidence level are set: Image 4, Image 5, Image 6, and Image 7. The ratio of the Higgs boson coupling modifiers Image 8 is constrained to be in the interval (−157,+199) at 95% confidence level. Assuming Image 9, this interval becomes (−166,+208)

Identification of low-momentum muons in the CMS detector using multivariate techniques in proton-proton collisions at √s = 13.6 TeV

"Soft"muons with a transverse momentum below 10 GeV are featured in many processes studied by the CMS experiment, such as decays of heavy-flavor hadrons or rare tau lepton decays. Maximizing the selection efficiency for these muons, while simultaneously suppressing backgrounds from long-lived light-flavor hadron decays, is therefore important for the success of the CMS physics program. Multivariate techniques have been shown to deliver better muon identification performance than traditional selection techniques. To take full advantage of the large data set currently being collected during Run 3 of the CERN LHC, a new multivariate classifier based on a gradient-boosted decision tree has been developed. It offers a significantly improved separation of signal and background muons compared to a similar classifier used for the analysis of the Run 2 data. The performance of the new classifier is evaluated on a data set collected with the CMS detector in 2022 and 2023, corresponding to an integrated luminosity of 62 fb-

Search for the Higgs boson decays to a ρ0, ϕ, or K⁎0 meson and a photon in proton-proton collisions at s=13TeV

Three rare decay processes of the Higgs boson to a ρ(770)0, ϕ(1020), or K⁎(892)0 meson and a photon are searched for using s=13TeV proton-proton collision data collected by the CMS experiment at the LHC. Events are selected assuming the mesons decay into a pair of charged pions, a pair of charged kaons, or a charged kaon and pion, respectively. Depending on the Higgs boson production mode, different triggering and reconstruction techniques are adopted. The analyzed data sets correspond to integrated luminosities up to 138fb−1, depending on the reconstructed final state. After combining various data sets and categories, no significant excess above the background expectations is observed. Upper limits at 95% confidence level on the Higgs boson branching fractions into ρ(770)0γ, ϕ(1020)γ, and K⁎(892)0γ are determined to be 3.7×10−4, 3.0×10−4, and 3.0×10−4, respectively. In case of the ρ(770)0γ and ϕ(1020)γ channels, these are the most stringent experimental limits to date

Measurement of the Higgs boson production via vector boson fusion and its decay into bottom quarks in proton-proton collisions at √<i>s</i>=13 TeV

A measurement of the Higgs boson (H) production via vector boson fusion (VBF) and its decay into a bottom quark-antiquark pair (b ¯b) is presented using proton-proton collision data recorded by the CMS experiment at √s = 13 TeV and corresponding to an integrated luminosity of 90.8 fb−1. Treating the gluon-gluon fusion process as a background and constraining its rate to the value expected in the standard model (SM) within uncertainties, the signal strength of the VBF process, defined as the ratio of the observed signal rate to that predicted by the SM, is measured to be μqqH Hb¯b = 1.01+0.55−0.46. The VBF signal is observed with a significance of 2.4 standard deviations relative to the background prediction, while the expected significance is 2.7 standard deviations. Considering inclusive Higgs boson production and decay into bottom quarks, the signal strength is measured to be μincl.Hb¯b = 0.99+0.48−0.41, corresponding to an observed (expected) significance of 2.6 (2.9) standard deviations

Measurement of multidifferential cross sections for dijet production in proton–proton collisions at s=13TeV

A measurement of the dijet production cross section is reported based on proton–proton collision data collected in 2016 at s=13TeV by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of up to 36.3fb-1. Jets are reconstructed with the anti-kT algorithm for distance parameters of R=0.4 and 0.8. Cross sections are measured double-differentially (2D) as a function of the largest absolute rapidity |y|max of the two jets with the highest transverse momenta pT and their invariant mass m1,2, and triple-differentially (3D) as a function of the rapidity separation y∗, the total boost yb, and either m1,2 or the average pT of the two jets. The cross sections are unfolded to correct for detector effects and are compared with fixed-order calculations derived at next-to-next-to-leading order in perturbative quantum chromodynamics. The impact of the measurements on the parton distribution functions and the strong coupling constant at the mass of the Z boson is investigated, yielding a value of αS(mZ)=0.1179±0.0019. © The Author(s) 2024