WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 20Nuclear Modification of Y States in Ppb Collisions at Root S-Nn=5.02 Tev(Elsevier, 2022) Tumasyan, A.; Karapınar, GülerProduction 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: 9Citation - Scopus: 13Probing Charm Quark Dynamics Via Multiparticle Correlations in Pb-Pb Collisions at Root S(nn)=5.02 Tev(Amer Physical Soc, 2022) Tumasyan, A.; Karapınar, GülerMultiparticle azimuthal correlations of prompt D-0 mesons arc measured in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of root s(NN) = 5.02 TeV. For the first time, a four-particle cumulant method is used to extract the second Fourier coefficient of the azimuthal distribution (v(2)) of D-0 mesons as a function of event centrality and the D-0 transverse momentum. The ratios of the four-particle v(2) values to previously measured two-particle cumulant results provide direct experimental access to event-by-event fluctuations of charm quark azimuthal anisotropies. These ratios are also found to be comparable to those of inclusive charged particles in the event. However, hints of deviations are seen in the most central and peripheral collisions. To investigate the origin of flow fluctuations in the charm sector, these measurements are compared to a model implementing fluctuations of charm quark energy loss via collisional or radiative processes in the quark-gluon plasma. These models cannot quantitatively describe the data over the full transverse momentum and centrality ranges, although the calculations with collisional energy loss provide a better description of the data.Article Citation - WoS: 26First Search for Exclusive Diphoton Production at High Mass With Tagged Protons in Proton-Proton Collisions at Root S=13 Tev(Amer Physical Soc, 2022) Tumasyan, A.; Karapınar, GülerA search for exclusive two-photon production via photon exchange in proton-proton collisions, pp -> p gamma gamma p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb(-1) collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeVat the LHC. Events are selected with a diphoton invariant mass above 350 GeVand with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons match the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% confidence level are vertical bar zeta(1)vertical bar < 2.9 x 10(-1)3 GeV-4 and vertical bar zeta(2)vertical bar < 6.0 x 10(-13) GeV-4.Article Citation - WoS: 6Citation - Scopus: 27Measurement of the Inclusive and Differential Higgs Boson Production Cross Sections in the Decay Mode To a Pair of Tau Leptons in Pp Collisions at Root S=13 Tev(Amer Physical Soc, 2022) Tumasyan, A.; Karapınar, GülerMeasurements of the inclusive and differential fiducial cross sections of the Higgs boson are presented, using the tau lepton decay channel. The differential cross sections are measured as functions of the Higgs boson transverse momentum, jet multiplicity, and transverse momentum of the leading jet in the event, if any. The analysis is performed using proton-proton collision data collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb-1. These are the first differential measurements of the Higgs boson cross section in the final state of two tau leptons. In final states with a large jet multiplicity or with a Lorentz-boosted Higgs boson, these measurements constitute a significant improvement over measurements performed in other final states.Article Citation - WoS: 19Citation - Scopus: 18Measurement of W-+/-gamma Differential Cross Sections in Proton-Proton Collisions at Root S=13 Tev and Effective Field Theory Constraints(Amer Physical Soc, 2022) Tumasyan, A.; Karapınar, GülerDifferential cross section measurements of W(+/-)y production in proton-proton collisions at root s = 13 TeV are presented. The data set used in this study was collected with the CMS detector at the CERN LHC in 2016-2018 with an integrated luminosity of 138 fb(-1). Candidate events containing an electron or muon, a photon, and missing transverse momentum are selected. The measurements are compared with standard model predictions computed at next-to-leading and next-to-next-to-leading orders in perturbative quantum chromodynamics. Constraints on the presence of TeV-scale new physics affecting the WW gamma vertex are determined within an effective field theory framework, focusing on the O-3w operator. A simultaneous measurement of the photon transverse momentum and the azimuthal angle of the charged lepton in a special reference frame is performed. This two-dimensional approach provides up to a factor of ten more sensitivity to the interference between the standard model and the O-3w contribution than using the transverse momentum alone.Article Citation - WoS: 20Citation - Scopus: 25Precision Measurement of the W Boson Decay Branching Fractions in Proton-Proton Collisions at Root S=13 Tev(Amer Physical Soc, 2022) Tumasyan, A.; Karapınar, GülerThe leptonic and inclusive hadronic decay branching fractions of the W boson are measured using proton-proton collision data collected at p s = 13 TeV by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb???1. Events characterized by the production of one or two W bosons are selected and categorized based on the multiplicity and flavor of reconstructed leptons, the number of jets, and the number of jets identified as originating from the hadronization of b quarks. A binned maximum likelihood estimate of the W boson branching fractions is performed simultaneously in each event category. The measured branching fractions of the W boson decaying into electron, muon, and tau lepton final states are (10.83 ?? 0.10)%, (10.94 ?? 0.08)%, and (10.77 ?? 0.21)%, respectively, consistent with lepton flavor universality for the weak interaction. The average leptonic and inclusive hadronic decay branching fractions are estimated to be (10.89 ?? 0.08)% and (67.32 ?? 0.23)%, respectively. Based on the hadronic branching fraction, three standard model quantities are subsequently derived: the sum of squared elements in the first two rows of the Cabibbo???Kobayashi???Maskawa (CKM) matrix Pij IVijI2 = 1.984 ?? 0.021, the CKM element IVcsI = 0.967 ?? 0.011, and the strong coupling constant at the W boson mass scale, ??S(m2W) = 0.095 ?? 0.033.Article Citation - WoS: 19Citation - Scopus: 15A New Calibration Method for Charm Jet Identification Validated With Proton-Proton Collision Events at Root S=13 Tev(IOP Publishing Ltd, 2022) Tumasyan, A.; Karapınar, GülerMany measurements at the LHC require efficient identification of heavy-flavour jets, i.e. jets originating from bottom (b) or charm (c) quarks. An overview of the algorithms used to identify c jets is described and a novel method to calibrate them is presented. This new method adjusts the entire distributions of the outputs obtained when the algorithms are applied to jets of different flavours. It is based on an iterative approach exploiting three distinct control regions that are enriched with either b jets, c jets, or light-flavour and gluon jets. Results are presented in the form of correction factors evaluated using proton-proton collision data with an integrated luminosity of 41.5 fb(-1) at root s = 13 TeV, collected by the CMS experiment in 2017. The closure of the method is tested by applying the measured correction factors on simulated data sets and checking the agreement between the adjusted simulation and collision data. Furthermore, a validation is performed by testing the method on pseudodata, which emulate various mismodelling conditions. The calibrated results enable the use of the full distributions of heavy-flavour identification algorithm outputs, e.g. as inputs to machine-learning models. Thus, they are expected to increase the sensitivity of future physics analyses.Article Citation - WoS: 6Citation - Scopus: 13Search for a W' Boson Decaying To a Vector-Like Quark and a Top or Bottom Quark in the All-Jets Final State at Root S=13 Tev(Springer, 2022) Tumasyan, A.; Karapınar, GülerA search is presented for a heavy W' boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using protonproton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb(-1) at a center-of-mass energy of 13 TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are selected using jet substructure techniques to reduce standard model backgrounds, resulting in a distinct three-jet W boson decay signature. No significant deviation in data with respect to the standard model background prediction is observed. Upper limits are set at 95% confidence level on the product of the W' boson cross section and the final state branching fraction. A W boson with a mass below 3.1 TeV is excluded, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.Article Citation - WoS: 34Citation - Scopus: 49Measurement of the Inclusive and Differential Wz Production Cross Sections, Polarization Angles, and Triple Gauge Couplings in Pp Collisions at Root S=13 Tev(Springer, 2022) Tumasyan, A.; Karapınar, GülerThe associated production of a W and a Z boson is studied in final states with multiple leptons produced in proton-proton (pp) collisions at a centre-of-mass energy of 13 TeV using 137 fb(-1) of data collected with the CMS detector at the LHC. A measurement of the total inclusive production cross section yields sigma(tot)(pp -> WZ) = 50.6 +/- 0.8 (stat) +/- 1.5 (syst) +/- 1.1 (lumi) +/- 0.5 (theo) pb. Measurements of the fiducial and differential cross sections for several key observables are also performed in all the final-state lepton flavour and charge compositions with a total of three charged leptons, which can be electrons or muons. All results are compared with theoretical predictions computed up to next-to-next-to-leading order in quantum chromodynamics plus next-to-leading order in electroweak theory and for various sets of parton distribution functions. The results include direct measurements of the charge asymmetry and the W and Z vector boson polarization. The first observation of longitudinally polarized W bosons in WZ production is reported. Anomalous gauge couplings are searched for, leading to new constraints on beyond-the-standard-model contributions to the WZ triple gauge coupling.Article Citation - WoS: 12Citation - Scopus: 19Search for Charged-Lepton Flavor Violation in Top Quark Production and Decay in Pp Collisions at Root S=13 Tev(Springer, 2022) Tumasyan, A.; Karapınar, GülerResults are presented from a search for charged-lepton flavor violating (CLFV) interactions in top quark production and decay in pp collisions at a center-of-mass energy of 13 TeV. The events are required to contain one oppositely charged electron-muon pair in the final state, along with at least one jet identified as originating from a bottom quark. The data correspond to an integrated luminosity of 138 fb(-1), collected by the CMS experiment at the LHC. This analysis includes both the production (q -> e mu t) and decay (t -> e mu q) modes of the top quark through CLFV interactions, with q referring to a u or c quark. These interactions are parametrized using an effective field theory approach. With no significant excess over the standard model expectation, the results are interpreted in terms of vector-, scalar-, and tensor-like CLFV four-fermion effective interactions. Finally, observed exclusion limits are set at 95% confidence levels on the respective branching fractions of a top quark to an e mu pair and an up (charm) quark of 0.13 x 10(-6) (1.31 x 10(-6)), 0.07 x 10(-6) (0.89 x 10(-6)), and 0.25 x 10(-6) (2.59 x 10(-6)) for vector, scalar, and tensor CLFV interactions, respectively.