WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Start date: 2020Subject: search.filters.subject.CMS

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  • Article
    Two-Particle Azimuthal Correlations in Γp Interactions Using Ppb Collisions at √snn=8.16 Tev
    (ELSEVIER, 2023) Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Del Valle, A. Escalante; Fruehwirth, R.; Jeitler, M.
    The first measurements of the Fourier coefficients (V-n Delta) of the azimuthal distributions of charged hadrons emitted from photon-proton (gamma p) interactions are presented. The data are extracted from 68.8nb(-1) of ultra-peripheral proton-lead (pPb) collisions at root s(NN)= 8.16 TeV using the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This gamma p system provides a set of unique initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The V-n Delta coefficients are presented in ranges of event multiplicity and transverse momentum (p(T)) and are compared to corresponding hadronic minimum bias pPb results. For a given multiplicity range, the mean p(T) of charged particles is smaller in gamma p than in pPb collisions. For both the gamma p and pPb samples, V-1 Delta is negative, V-2 Delta is positive, and V-3 Delta consistent with 0. For each multiplicity and p(T) range, V-2 Delta is larger for gamma p events. The gamma p data are consistent with model predictions that have no collective effects. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).
  • Article
    Citation - WoS: 20
    Nuclear Modification of Y States in Ppb Collisions at Root S-Nn=5.02 Tev
    (Elsevier, 2022) Tumasyan, A.; Karapınar, Güler
    Production cross sections of Y(1S), Y(2S), and Y(3S) states decaying into mu(+)mu(-) in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at root S-NN= 5.02 TeV. A comparison is made with corresponding cross sections obtained with ppdata measured at the same collision energy and scaled by the Pb nucleus mass number. The nuclear modification factor for Y(1S) is found to be R-pPb(Y(1S)) = 0.806 +/- 0.024 (stat)+/- 0.059 (syst). Similar results for the excited states indicate a sequential suppression pattern, such that R-pPb(Y(1S)) > R-pPb(Y(2S)) > R-pPb(Y(3S)). The suppression of all states is much less pronounced in pPbthan in PbPbcollisions, and independent of transverse momentum p(T)(Y) and center-of-mass rapidity y(CM)(Y) of the individual Y state in the studied range p(T)(Y) < 30GeV/c and |y(CM)(Y)| < 1.93. Models that incorporate final-state effects of bottomonia in pPb collisions are in better agreement with the data than those which only assume initial-state modifications. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
  • Article
    Citation - WoS: 8
    Citation - Scopus: 6
    Search for High-Mass Resonances Decaying To a Jet and a Lorentz-Boosted Resonance in Proton-Proton Collisions at Root S=13 Tev
    (Elsevier, 2022) Karapınar, Güler
    A search is reported for high-mass hadronic resonances that decay to a parton and a Lorentz-boosted resonance, which in turn decays into a pair of partons. The search is based on data collected with the CMS detector at the LHC in proton-proton collisions at root s = 13 TeV, corresponding to an integrated luminosity of 138 fb(-1). The boosted resonance is reconstructed as a single wide jet with substructure consistent with a two-body decay. The high-mass resonance is thus considered as a dijet system. The jet substructure information and the kinematic properties of cascade resonance decays are exploited to disentangle the signal from the large quantum chromodynamics multijet background. The dijet mass spectrum is analyzed for the presence of new high-mass resonances, and is found to be consistent with the standard model background predictions. Results are interpreted in a warped extra dimension model where the high-mass resonance is a Kaluza-Klein gluon, the boosted resonance is a radion, and the final state partons are all gluons. Limits on the production cross section are set as a function of the Kaluza-Klein gluon and radion masses. These limits exclude at 95% confidence level models with Kaluza-Klein gluon masses in the range 2.0 to 4.3 TeV and radion masses in the range 0.20 to 0.74TeV. By exploring a novel experimental signature, the observed limits on the Kaluza-Klein gluon mass are extended by up to about 1 TeV compared to previous searches. (C) 2022 The Author(s). Published by Elsevier B.V.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 16
    Observation of Bs 0 Mesons and Measurement of the Bs 0/B+ Yield Ratio in Pbpb Collisions at [formula Presented] Tev
    (Elsevier B.V., 2022) Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Erö, J.; Kirakosyan, M.
    The Bs 0 and B+ production yields are measured in PbPb collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data sample, collected with the CMS detector at the LHC, corresponds to an integrated luminosity of 1.7 nb−1. The mesons are reconstructed in the exclusive decay channels B→s0J/ψ(μ+μ−)ϕ(K+K−) and B→+J/ψ(μ+μ−)K+, in the transverse momentum range 7–50 GeV/c and absolute rapidity 0–2.4. The Bs 0 meson is observed with a statistical significance in excess of five standard deviations for the first time in nucleus-nucleus collisions. The measurements are performed as functions of the transverse momentum of the B mesons and of the PbPb collision centrality. The ratio of production yields of Bs 0 and B+ is measured and compared to theoretical models that include quark recombination effects. © 2022 The Author(s)
  • Article
    Citation - WoS: 5
    Citation - Scopus: 7
    Search for Wγ Resonances in Proton-Proton Collisions at S=13 TeV Using Hadronic Decays of Lorentz-Boosted W Bosons
    (Elsevier B.V., 2022) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Alves, G.A.
    A search for Wγ resonances in the mass range between 0.7 and 6.0 TeV is presented. The W boson is reconstructed via its hadronic decays, with the final-state products forming a single large-radius jet, owing to a high Lorentz boost of the W boson. The search is based on proton-proton collision data at s=13 TeV, corresponding to an integrated luminosity of 137 fb−1, collected with the CMS detector at the LHC in 2016–2018. The Wγ mass spectrum is parameterized with a smoothly falling background function and examined for the presence of resonance-like signals. No significant excess above the predicted background is observed. Model-specific upper limits at 95% confidence level on the product of the cross section and branching fraction to the Wγ channel are set. Limits for narrow resonances and for resonances with an intrinsic width equal to 5% of their mass, for spin-0 and spin-1 hypotheses, range between 0.17 fb at 6.0 TeV and 55 fb at 0.7 TeV. These are the most restrictive limits to date on the existence of such resonances over a large range of probed masses. In specific heavy scalar (vector) triplet benchmark models, narrow resonances with masses between 0.75 (1.15) and 1.40 (1.36) TeV are excluded for a range of model parameters. Model-independent limits on the product of the cross section, signal acceptance, and branching fraction to the Wγ channel are set for minimum Wγ mass thresholds between 1.5 and 8.0 TeV. © 2022 The Author(s)
  • Article
    Citation - WoS: 13
    Citation - Scopus: 15
    Strategies and Performance of the Cms Silicon Tracker Alignment During Lhc Run 2
    (Elsevier, 2022) Karapınar, Güler; CMS Collaboration
    The strategies for and the performance of the CMS silicon tracking system alignment during the 2015-2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios.
  • Article
    Citation - WoS: 40
    Observation of Electroweak Production of W Gamma With Two Jets in Proton-Proton Collisions at Root S=13 Tev
    (Elsevier, 2020) Karapınar, Güler
    A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak W gamma jj production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for W gamma production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators. (C) 2020 The Author(s). Published by Elsevier B.V.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 19
    Study of J/Ψ Meson Production Inside Jets in pp Collisions at S=8 TeV
    (Elsevier B.V., 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Hensel, C.
    A study of the production of prompt J/ψ mesons contained in jets in proton-proton collisions at s=8TeV is presented. The analysis is based on data corresponding to an integrated luminosity of 19.1 fb−1 collected with the CMS detector at the LHC. For events with at least one observed jet, the angular separation between the J/ψ meson and the jet is used to test whether the J/ψ meson is part of the jet. The analysis shows that most prompt J/ψ mesons having energy above 15 GeV and rapidity |y|<1 are contained in jets with pseudorapidity |η<inf>jet</inf>|<1. The differential distributions of the probability to have a J/ψ meson contained in a jet as a function of jet energy for a fixed J/ψ energy fraction are compared to a theoretical model using the fragmenting jet function approach. The data agree best with fragmenting jet function calculations that use a long-distance matrix element parameter set in which prompt J/ψ mesons are predicted to be unpolarized. This technique demonstrates a new way to test predictions for prompt J/ψ production using nonrelativistic quantum chromodynamics. © 2020 Elsevier B.V.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 8
    Search for the Rare Decay of the W Boson Into a Pion and a Photon in Proton-Proton Collisions at S=13tev
    (Elsevier B.V., 2021) Sirunyan,A.M.; Karapınar, Güler; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Chistov,R.
    A search is performed for the rare decay W±→π±γ in proton-proton collisions at s=13TeV. Data corresponding to an integrated luminosity of 137fb−1 were collected during 2016 to 2018 with the CMS detector. This analysis exploits a novel search strategy based on W boson production in top quark pair events. An inclusive search for the W±→π±γ decay is not optimal at the LHC because of the high trigger thresholds. Instead, a trigger selection is exploited in which the W boson originating from one of the top quarks is used to tag the event in a leptonic decay. The W boson emerging from the other top quark is used to search for the W±→π±γ signature. Such decays are characterized by an isolated track pointing to a large energy deposit, and by an isolated photon of large transverse momentum. The presence of b quark jets reduces the background from the hadronization of light-flavor quarks and gluons. The W±→π±γ decay is not observed. An upper exclusion limit is set to this branching fraction, corresponding to 1.50×10−5 at 95% confidence level, whereas the expected upper exclusion limit is 0.85−0.29 +0.52×10−5. © 2021 The Author(s)
  • Article
    Citation - WoS: 70
    Citation - Scopus: 75
    Search for Singly and Pair-Produced Leptoquarks Coupling To Third-Generation Fermions in Proton-Proton Collisions at S=13 Tev
    (Elsevier B.V., 2021) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Chistov,R.
    A search for leptoquarks produced singly and in pairs in proton-proton collisions is presented. We consider the leptoquark (LQ) to be a scalar particle of charge −1/3e coupling to a top quark plus a tau lepton (tτ) or a bottom quark plus a neutrino (bν), or a vector particle of charge +2/3e, coupling to tν or bτ. These choices are motivated by models that can explain a series of anomalies observed in the measurement of B meson decays. In this analysis the signatures tτνb and tτν are probed, using data recorded by the CMS experiment at the CERN LHC at s=13 TeV and that correspond to an integrated luminosity of 137 fb−1. These signatures have not been previously explored in a dedicated search. The data are found to be in agreement with the standard model prediction. Lower limits at 95% confidence level are set on the LQ mass in the range 0.98–1.73 TeV, depending on the LQ spin and its coupling λ to a lepton and a quark, and assuming equal couplings for the two LQ decay modes considered. These are the most stringent constraints to date on the existence of leptoquarks in this scenario. © 2021 The Author(s)