Rectorate / Rektörlük
Permanent URI for this collectionhttps://hdl.handle.net/11147/6849
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Article Citation - WoS: 27Citation - Scopus: 60Search for Bottom-Type, Vectorlike Quark Pair Production in a Fully Hadronic Final State in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Dremin,I.A search is described for the production of a pair of bottom-type vectorlike quarks (VLQs), each decaying into a b or b¯ quark and either a Higgs or a Z boson, with a mass greater than 1000 GeV. The analysis is based on data from proton-proton collisions at a 13 TeV center-of-mass energy recorded at the CERN LHC, corresponding to a total integrated luminosity of 137 fb-1. As the predominant decay modes of the Higgs and Z bosons are to a pair of quarks, the analysis focuses on final states consisting of jets resulting from the six quarks produced in the events. Since the two jets produced in the decay of a highly Lorentz-boosted Higgs or Z boson can merge to form a single jet, nine independent analyses are performed, categorized by the number of observed jets and the reconstructed event mode. No signal in excess of the expected background is observed. Lower limits are set on the VLQ mass at 95% confidence level equal to 1570 GeV in the case where the VLQ decays exclusively to a b quark and a Higgs boson, 1390 GeV for when it decays exclusively to a b quark and a Z boson, and 1450 GeV for when it decays equally in these two modes. These limits represent significant improvements over the previously published VLQ limits. © 2020 CERN.Article Citation - WoS: 41Citation - Scopus: 45Measurements of P P → Z Z Production Cross Sections and Constraints on Anomalous Triple Gauge Couplings at √s=13tev(Springer Science and Business Media Deutschland GmbH, 2021) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Bychkova,O.The production of Z boson pairs in proton–proton (p p) collisions, p p → (Z / γ∗) (Z / γ∗) → 2 ℓ2 ℓ′, where ℓ, ℓ′= e or μ , is studied at a center-of-mass energy of 13TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137fb-1, collected during 2016–2018. The Z Z production cross section, σtot(pp→ZZ)=17.4±0.3(stat)±0.5(syst)±0.4(theo)±0.3(lumi) pb, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region 60<mℓ+ℓ-<120GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous Z Z Z and Z Z γ couplings. © 2021, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 42Citation - Scopus: 59Search for Dark Matter Produced in Association With a Leptonically Decaying Z Boson in Proton–proton Collisions at √s=13te(Institute for Ionics, 2021) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Bergauer,T.; Dragicevic,M.; Erö,J.; Kodolova,O.A search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton–proton collision data at a center-of-mass energy of 13Te, collected by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137fb-1. The search uses the decay channels Z → e e and Z → μ μ. No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions. © 2020, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 14Citation - Scopus: 27Search for Resonant Pair Production of Higgs Bosons in the Bbzz Channel in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Philippov,D.A search for the production of a narrow-width resonance decaying into a pair of Higgs bosons decaying into the bbZZ channel is presented. The analysis is based on data collected with the CMS detector during 2016, in proton-proton collisions at the LHC, corresponding to an integrated luminosity of 35.9 fb-1. The final states considered are the ones where one of the Z bosons decays into a pair of muons or electrons, and the other Z boson decays to either a pair of quarks or a pair of neutrinos. Upper limits at 95% confidence level are placed on the production of narrow-width spin-0 or spin-2 particles decaying to a pair of Higgs bosons, in models with and without an extended Higgs sector. For a resonance mass range between 260 and 1000 GeV, limits on the production cross section times branching fraction of a spin-0 and spin-2 resonance range from 0.1 to 5.0 pb and 0.1 to 3.6 pb, respectively. These results set limits in parameter space in bulk Randall-Sundrum radion, Kaluza-Klein excitation of the graviton, and next-to-minimal two-Higgs doublet models (N2HDMs). For specific choices of parameters the N2HDM can be excluded in a mass range between 360 and 620 GeV for a resonance decaying to two Higgs bosons. This is the first search for Higgs boson resonant pair production in the bbZZ channel. © 2020 American Physical Society. All rights reserved.Article Citation - WoS: 33Citation - Scopus: 52Observation of the Production of Three Massive Gauge Bosons at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Dremin,I.The first observation is reported of the combined production of three massive gauge bosons (VVV with V=W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is based on a data sample recorded by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 137 fb-1. The searches for individual WWW, WWZ, WZZ, and ZZZ production are performed in final states with three, four, five, and six leptons (electrons or muons), or with two same-sign leptons plus one or two jets. The observed (expected) significance of the combined VVV production signal is 5.7 (5.9) standard deviations and the corresponding measured cross section relative to the standard model prediction is 1.02-0.23+0.26. The significances of the individual WWW and WWZ production are 3.3 and 3.4 standard deviations, respectively. Measured production cross sections for the individual triboson processes are also reported. © 2020 CERN.Article Citation - WoS: 12Citation - Scopus: 32Observation of the Bs0 →x (3872)φ Decay(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Andreev,V.Using a data sample of proton-proton collisions at s=13 TeV, corresponding to an integrated luminosity of 140 fb-1 collected by the CMS experiment in 2016-2018, the Bs0→X(3872)φ decay is observed. Decays into J/ψ+π- and K+K- are used to reconstruct, respectively, the X(3872) and φ. The ratio of the product of branching fractions B[Bs0→X(3872)φ]B[X(3872)→J/ψ+π-] to the product B[Bs0→(2S)φ]B[ψ(2S)→J/ψ+π-] is measured to be [2.21±0.29(stat)±0.17(syst)]%. The ratio B[Bs0→X(3872)φ]/B[B0→X(3872)K0] is found to be consistent with one, while the ratio B[Bs0→X(3872)φ]/B[B+→X(3872)K+] is two times smaller. This suggests a difference in the production dynamics of the X(3872) in B0 and Bs0 meson decays compared to B+. The reported observation may shed new light on the nature of the X(3872) particle. © 2020 CERN.Article Citation - WoS: 39Citation - Scopus: 48W+w- Boson Pair Production in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Dremin,I.A measurement of the W+W- boson pair production cross section in proton-proton collisions at s=13 TeV is presented. The data used in this study are collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 35.9 fb-1. The W+W- candidate events are selected by requiring two oppositely charged leptons (electrons or muons). Two methods for reducing background contributions are employed. In the first one, a sequence of requirements on kinematic quantities is applied allowing a measurement of the total production cross section, 117.6±6.8 pb, which agrees well with the theoretical prediction. Fiducial cross sections are also reported for events with zero or one jet, and the change in the zero-jet fiducial cross section with the jet transverse momentum threshold is measured. Normalized differential cross sections are reported within the fiducial region. A second method for suppressing background contributions employs two random forest classifiers. The analysis based on this method includes a measurement of the total production cross section and also a measurement of the normalized jet multiplicity distribution in W+W- events. Finally, a dilepton invariant mass distribution is used to probe for physics beyond the standard model in the context of an effective field theory, and constraints on the presence of dimension-6 operators are derived. © 2020 CERN.Article Citation - WoS: 20Citation - Scopus: 29Measurement of the Top Quark Yukawa Coupling From Tt¯ Kinematic Distributions in the Dilepton Final State in Proton-Proton Collisions at S=13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Chistov,R.A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at s=13 TeV, corresponding to an integrated luminosity of 137 fb-1, recorded with the CMS detector. The coupling strength with respect to the standard model value, Yt, is determined from kinematic distributions in tt¯ final states containing ee, μμ, or eμ pairs. Variations of the Yukawa coupling strength lead to modified distributions for tt¯ production. In particular, the distributions of the mass of the tt¯ system and the rapidity difference of the top quark and antiquark are sensitive to the value of Yt. The measurement yields a best fit value of Yt=1.16-0.35+0.24, bounding Yt<1.54 at a 95% confidence level. © 2020 CERN.Article Citation - WoS: 16Citation - Scopus: 39Measurements of the W Boson Rapidity, Helicity, Double-Differential Cross Sections, and Charge Asymmetry in Pp Collisions at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Dremin,I.The differential cross section and charge asymmetry for inclusive W boson production at s=13 TeV is measured for the two transverse polarization states as a function of the W boson absolute rapidity. The measurement uses events in which a W boson decays to a neutrino and either a muon or an electron. The data sample of proton-proton collisions recorded with the CMS detector at the LHC in 2016 corresponds to an integrated luminosity of 35.9 fb-1. The differential cross section and its value normalized to the total inclusive W boson production cross section are measured over the rapidity range |yW|<2.5. In addition to the total fiducial cross section, the W boson double-differential cross section, d2σ/dpTd|η|, and the charge asymmetry are measured as functions of the charged lepton transverse momentum and pseudorapidity. The precision of these measurements is used to constrain the parton distribution functions of the proton using the next-to-leading order NNPDF3.0 set. © 2020 CERN.Article Citation - WoS: 41Citation - Scopus: 42Measurement of Inclusive Jet Production and Nuclear Modifications in Ppb Collisions at √snn = 5.02 Tev(Springer Nature, 2016) Khachatryan,V.; Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Asilar,E.; Bergauer,T.; Fernandez,M.Inclusive jet production in pPb collisions at a nucleon–nucleon (NN) center-of-mass energy of √sNN= 5.02TeV is studied with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 30.1 nb- 1 is analyzed. The jet transverse momentum spectra are studied in seven pseudorapidity intervals covering the range - 2.0 < ηCM< 1.5 in the NN center-of-mass frame. The jet production yields at forward and backward pseudorapidity are compared and no significant asymmetry about ηCM= 0 is observed in the measured kinematic range. The measurements in the pPb system are compared to reference jet spectra obtained by extrapolation from previous measurements in pp collisions at √s=7TeV. In all pseudorapidity ranges, nuclear modifications in inclusive jet production are found to be small, as predicted by next-to-leading order perturbative QCD calculations that incorporate nuclear effects in the parton distribution functions. © 2016, CERN for the benefit of the CMS collaboration.