Browsing by Author "Lee, J."

Now showing 1 - 9 of 9

Citation - Scopus: 2
Constraints on Standard Model Effective Field Theory for a Higgs Boson Produced in Association with W or Z Bosons in the H → B(b)over-Bar Decay Channel in Proton-Proton Collisions at √s=13 TeV
(Springer, 2025) Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Lee, J.
A standard model effective field theory (SMEFT) analysis with dimension-six operators probing nonresonant new physics effects is performed in the Higgs-strahlung process, where the Higgs boson is produced in association with a W or Z boson, in proton-proton collisions at a center-of-mass energy of 13 TeV. The final states in which the W or Z boson decays leptonically and the Higgs boson decays to a pair of bottom quarks are considered. The analyzed data were collected by the CMS experiment between 2016 and 2018 and correspond to an integrated luminosity of 138 fb(-1). An approach designed to simultaneously optimize the sensitivity to Wilson coefficients of multiple SMEFT operators is employed. Likelihood scans as functions of the Wilson coefficients that carry SMEFT sensitivity in this final state are performed for different expansions in SMEFT. The results are consistent with the predictions of the standard model.
Citation - WoS: 7
Constraints on the Higgs Boson Self-Coupling From the Combination of Svingle and Double Higgs Boson Production in Proton-Proton Collisions at √s=13 Tev
(Elsevier, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Lee, J.
The Higgs boson (H) trilinear self-coupling, lambda(3), is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at root s = 13 TeV. The combination of event categories enriched in single-H and HH events is used to measure k(lambda), defined as the value of lambda(3) normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of k(lambda) outside the interval -1.2 < k(lambda) < 7.5 are excluded at 2 sigma confidence level, which is compatible with the expected range of -2.0< k(lambda) < 7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) k(lambda) interval is constrained to be within -1.4 < k(lambda) < 7.8 (-2.3 < k(lambda) < 7.8) at 2 sigma confidence level.
Citation - WoS: 1
Determination of the Strong Coupling and Its Running from Measurements of Inclusive Jet Production
(Elsevier, 2025) Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Lee, J.
The value of the strong coupling alpha(S) is determined in a comprehensive analysis at next-to-next-to-leading order accuracy in quantum chromodynamics. The analysis uses double-differential cross section measurements from the CMS Collaboration at the CERN LHC of inclusive jet production in proton-proton collisions at centre-of-mass energies of 2.76, 7, 8, and 13 TeV, combined with inclusive deep-inelastic data from HERA. The value alpha(S)(m(Z)) = 0.1176(-0.0016)(+0.0014) is obtained at the scale of the Z boson mass. By using the measurements in different intervals of jet transverse momentum, the running of alpha(S) is probed for energies between 100 and 1600GeV.
Citation - WoS: 3
Citation - Scopus: 3
Measurement of the Inclusive Cross Sections for W and Z Boson Production in Proton-Proton Collisions at √s=5.02 and 13 TeV
(Springer, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Lee, J.
Measurements of fiducial and total inclusive cross sections for W and Z boson production are presented in proton-proton collisions at root s = 5.02 and 13TeV. Electron and muon decay modes (l = e or mu) are studied in the data collected with the CMS detector in 2017, in dedicated runs with reduced instantaneous luminosity. The data sets correspond to integrated luminosities of 298 +/- 6 pb(-1) at 5.02TeV and 206 +/- 5 pb(-1) at 13TeV. Measured values of the products of the total inclusive cross sections and the branching fractions at 5.02TeV are sigma(pp -> W+ X)B(W -> l nu) = 7300 +/- 10 (stat) +/- 60 (syst) +/- 140 (lumi) pb, and sigma(pp -> Z+ X)B(Z -> l(+) l(-)) = 669 +/- 2 (stat)+/- 6 (syst)+/- 13 (lumi) pb for the dilepton invariant mass in the range of 60-120 GeV. The corresponding results at 13TeV are 20480 +/- 10 (stat)+/- 170 (syst)+/- 470 (lumi) pb and 1952 +/- 4 (stat)+/- 18 (syst)+/- 45 (lumi) pb. The measured values agree with cross section calculations at next-to-next-to-leading-order in perturbative quantum chromodynamics. Fiducial and total inclusive cross sections, ratios of cross sections of W+ and W- production as well as inclusive W and Z boson production, and ratios of these measurements at 5.02 and 13TeV are reported.
Citation - WoS: 2
Citation - Scopus: 3
Observation of the Ξb- → Ψ(2s)ξ- Decay and Studies of the Ξb(5945)0 Baryon in Proton-Proton Collisions at √s=13 Tev
(Amer Physical Soc, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Lee, J.
The first observation of the decay Xi(-)(b) -> psi(2S)Xi(-) and measurement of the branching ratio of Xi(-)(b) -> psi(2S)Xi(-) to Xi(-)(b) -> J/psi Xi(-) are presented. The J/psi and psi(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at root s = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb(-1). The branching fraction ratio is measured to be B(Xi(-)(b) -> psi(2S)Xi(-))/B(Xi(-)(b) -> J/psi Xi(-)) = 0.84(-0.19)(+0.21)(stat) +/- 0.10(syst) +/- 0.02(B), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the Xi(b)(5945)(0) baryon mass and natural width are also presented, using the Xi(-)(b)pi(+) final state, where the Xi(-)(b) baryon is reconstructed through the decays J/psi Xi(-), psi(2S)Xi(-), J/psi Lambda K-, and J/psi Sigma K-0(-). Finally, the fraction of Xi(-)(b) baryons produced from Xi(b)(5945)(0) decays is determined.
Citation - Scopus: 1
Probing Gluon Fluctuations in Nuclei With the First Energy-Dependent Measurement of Incoherent J/Ψ Photoproduction in Ultraperipheral PbPb Collisions
(American Physical Society, 2025) Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Lee, J.
Incoherent J/psi photoproduction in heavy ion ultraperipheral collisions (UPCs) provides a sensitive probe of localized, fluctuating gluonic structures within heavy nuclei. This Letter reports the first measurement of the photon-nucleon center-of-mass energy (W-gamma N) dependence of this process in PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using 1.52 nb(-1) of data recorded by the CMS experiment. The measurement covers a wide W-gamma N range of approximate to 40-400 GeV, probing gluons carrying a fraction x of nucleon momentum down to an unexplored regime of 6.5 x 10(-5). Compared to baseline predictions neglecting nuclear effects, the measured cross sections exhibit significantly greater suppression at lower x. Additionally, the ratio of incoherent to coherent photoproduction is found to be constant across the probed W-gamma N and x range, disfavoring the establishment of the black disk limit. This Letter provides critical insights into the x-dependent evolution of fluctuating gluonic structures within nuclei and calls for further advancements in theoretical models incorporating nuclear shadowing and gluon saturation.
Search for Heavy Neutral Higgs Bosons a and H in the T(t)over-Barz Channel in Proton-Proton Collisions at 13 TeV
(Elsevier, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Benato, L.; Bergauer, T.; Lee, J.
A direct search for new heavy neutral Higgs bosons A and H in the t (t) over barZ channel is presented, targeting the process pp -> A -> ZH with H -> t (t) over bar. For the first time, the channel with decays of the Z boson to muons or electrons in association with all-hadronic decays of the t (t) over bar system is targeted. The analysis uses proton-proton collision data collected at the CERN LHC with the CMS experiment at root s = 13 TeV, which correspond to an integrated luminosity of 138 fb(-1). No signal is observed. Upper limits on the product of the cross section and branching fractions are derived for narrow resonances A and H with masses up to 2100 and 2000GeV, respectively, assuming A boson production through gluon fusion. The results are also interpreted within two-Higgs-doublet models, where A and H are CP-odd and CP-even states, respectively, complementing and substantially extending the reach of previous searches.
Citation - WoS: 1
Search for the Higgs Boson Decays To a Ρ0 Φ, or K*0 Meson and a Photon in Proton-Proton Collisions at √s=13 Tev
(Elsevier, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Lee, J.
Three rare decay processes of the Higgs boson to a rho(770)(0), phi(1020), or K-* (892)(0) meson and a photon are searched for using root s = 13 TeV 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 138 fb(-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 rho(770)(0)gamma, phi(1020)gamma, and K-*(892)(0)gamma are determined to be 3.7 x 10(-4), 3.0 x 10(-4), and 3.0 x 10(-4), respectively. In case of the rho(770)(0)gamma and phi(1020)gamma channels, these are the most stringent experimental limits to date.
Citation - WoS: 1
Search for Vector-Like Leptons With Long-Lived Particle Decays in the CMS Muon System in Proton-Proton Collisions at √s=13 TeV
(Springer, 2025) Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Lee, J.
A first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model tau lepton. The pseudoscalar boson is assumed to have a mass below the tau(+)tau(-) threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb(-1). Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying tau lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.