Rectorate / Rektörlük

Permanent URI for this collectionhttps://hdl.handle.net/11147/6849

Browse

Now showing 1 - 20 of 800

Citation - WoS: 21
Citation - Scopus: 28
Angular Analysis of the Decay B+-> K*(892)(+)mu(+)mu(-) in Proton-Proton Collisions at Root S=8 Tev
(Springer, 2021) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
Angular distributions of the decay B+-> K*(892)(+)mu(+)mu(-) are studied using events collected with the CMS detector in root s = 8 TeV proton-proton collisions at the LHC, corresponding to an integrated luminosity of 20.0 fb(-1). The forward-backward asymmetry of the muons and the longitudinal polarization of the K*(892)(+) meson are determined as a function of the square of the dimuon invariant mass. These are the first results from this exclusive decay mode and are in agreement with a standard model prediction.
Citation - WoS: 146
Citation - Scopus: 194
Angular Analysis of the Decay B0 → K⁎0μ+μ− From Pp Collisions at √s=8 Tev
(Elsevier B.V., 2016) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Puerta Pelayo, J.; 01. Izmir Institute of Technology
The angular distributions and the differential branching fraction of the decay B0→K⁎(892)0μ+μ− are studied using data corresponding to an integrated luminosity of 20.5 fb−1 collected with the CMS detector at the LHC in pp collisions at s=8 TeV. From 1430 signal decays, the forward–backward asymmetry of the muons, the K⁎(892)0 longitudinal polarization fraction, and the differential branching fraction are determined as a function of the dimuon invariant mass squared. The measurements are among the most precise to date and are in good agreement with standard model predictions. © 2015 CERN for the benefit of the CMS Collaboration
Citation - WoS: 91
Citation - Scopus: 103
Angular Coefficients of Z Bosons Produced in Pp Collisions at S=8 Tev and Decaying To Μ+μ− as a Function of Transverse Momentum and Rapidity
(Elsevier B.V., 2015) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Gigi, D.; 01. Izmir Institute of Technology
Measurements of the five most significant angular coefficients, A0 through A4, for Z bosons produced in pp collisions at s=8 TeV and decaying to μ+μ− are presented as a function of the transverse momentum and rapidity of the Z boson. The integrated luminosity of the dataset collected with the CMS detector at the LHC corresponds to 19.7fb−1. These measurements provide comprehensive information about the Z boson production mechanisms, and are compared to the QCD predictions at leading order, next-to-leading order, and next-to-next-to-leading order in perturbation theory. © 2015 CERN for the benefit of the CMS Collaboration
Citation - WoS: 76
Citation - Scopus: 79
Azimuthal Anisotropy of Charged Particles With Transverse Momentum Up To 100 Gev/C in Pbpb Collisions at ?snn=5.02 Tev
(Elsevier Ltd., 2018-01) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
The Fourier coefficients v2 and v3 characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at sNN=5.02 TeV are measured with data collected by the CMS experiment. The measurements cover a broad transverse momentum range, 110 GeV/c range, where anisotropic azimuthal distributions should reflect the path-length dependence of parton energy loss in the created medium. Results are presented in several bins of PbPb collision centrality, spanning the 60% most central events. The v2 coefficient is measured with the scalar product and the multiparticle cumulant methods, which have different sensitivities to initial-state fluctuations. The values from both methods remain positive up to pT∼60–80 GeV/c, in all examined centrality classes. The v3 coefficient, only measured with the scalar product method, tends to zero for pT≳20 GeV/c. Comparisons between theoretical calculations and data provide new constraints on the path-length dependence of parton energy loss in heavy ion collisions and highlight the importance of the initial-state fluctuations.
Citation - WoS: 42
Citation - Scopus: 47
Azimuthal Decorrelation of Jets Widely Separated in Rapidity in Pp Collisions at ?s = 7 Tev
(Springer Verlag, 2016-08) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
The decorrelation in the azimuthal angle between the most forward and the most backward jets (Mueller-Navelet jets) is measured in data collected in pp collisions with the CMS detector at the LHC at s=7 TeV. The measurement is presented in the form of distributions of azimuthal-angle differences, Δϕ, between the Mueller-Navelet jets, the average cosines of (π − Δϕ), 2(π − Δϕ), and 3(π − Δϕ), and ratios of these cosines. The jets are required to have transverse momenta, pT, in excess of 35 GeV and rapidities, |y|, of less than 4.7. The results are presented as a function of the rapidity separation, Δy, between the Mueller-Navelet jets, reaching Δy up to 9.4 for the first time. The results are compared to predictions of various Monte Carlo event generators and to analytical predictions based on the DGLAP and BFKL parton evolution schemes.
Citation - WoS: 13
Citation - Scopus: 23
Bose-Einstein Correlations of Charged Hadrons in Proton-Proton Collisions at s=13 Tev
(Springer Verlag, 2020) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of Technology
Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at s = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at s = 7 TeV, as well as with theoretical predictions.
Citation - WoS: 166
Citation - Scopus: 136
Charged Particle Multiplicities in Pp Interactions at ?s = 0.9, 2.36, and 7tev
(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş Ali; Demir, Durmuş Ali; Karapınar, Güler; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of Science
Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of √s = 0.9, 2.36, and 7TeV, in five pseudorapidity ranges from |η| < 0.5 to |η| < 2.4. The data were collected with the minimum-bias trigger of the CMS experiment during the LHC commissioning runs in 2009 and the 7TeV run in 2010. The multiplicity distribution at √s = 0.9 TeV is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with √s is underestimated by most event generators. The average transverse momentum as a function of the multiplicity is also presented. The measurement of higher-order moments of the multiplicity distribution confirms the violation of Koba-Nielsen-Olesen scaling that has been observed at lower energies.
Citation - WoS: 78
Citation - Scopus: 74
Charged Particle Transverse Momentum Spectra in Pp Collisions at ?s = 0:9 and 7 Tev
(Springer Verlag, 2011) Karapınar, Güler; Karapınar, Güler; Demir, Durmuş Ali; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of Science
The charged particle transverse momentum (pT) spectra are presented for pp collisions at √s = 0:9 and 7TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 μb-1and 2.96 pb-1, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with leading and next-toleading order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT - 2pT=ps over the pT range up to 136 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at √s = 2:76TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy. Copyright CERN.
Citation - WoS: 205
Citation - Scopus: 203
Charged-Particle Nuclear Modification Factors in Pbpb and Ppb Collisions at ?snn=5.02 Tev
(Springer Verlag, 2017-04) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
The spectra of charged particles produced within the pseudorapidity window |η| < 1 at sNN=5.02 TeV are measured using 404 μb−1 of PbPb and 27.4 pb−1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pT< 400 GeV in pp and 0.7 < pT< 400 GeV in PbPb collisions. The corresponding nuclear modification factor, RAA, is measured in bins of collision centrality. The RAA in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the pT region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest pT measured, and approaches unity in the vicinity of pT = 200 GeV. The RAA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, RpA, up to 120 GeV. For pT> 20 GeV, RpA exhibits weak momentum dependence and shows a moderate enhancement above unity.[Figure not available: see fulltext.] © 2017, The Author(s).
Citation - WoS: 23
Citation - Scopus: 24
Charged-Particle Nuclear Modification Factors in Xexe Collisions at Root S-Nn=5.44 Tev
(Springer Verlag, 2018) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of Technology
The differential yields of charged particles having pseudorapidity within vertical bar eta vertical bar < 1 are measured using xenon-xenon (XeXe) collisions at root S-NN = 5.44 TeV. The data, corresponding to an integrated luminosity of 3.42 mu b(-1), were collected in 2017 by the CMS experiment at the LHC. The yields are reported as functions of collision centrality and transverse momentum, pT, from 0.5 to 100 GeV. A previously reported pT spectrum from proton-proton collisions at root S = 5.02 TeV is used for comparison after correcting for the difference in center-of-mass energy. The nuclear modification factors using this reference, R-AA*, are constructed and compared to previous measurements and theoretical predictions. In head-on collisions, the R-AA* has a value of 0.17 in the pT range of 6-8 GeV, but increases to approximately 0.7 at 100 GeV. Above approximate to 6 GeV, the XeXe data show a notably smaller suppression than previous results for lead-lead (PbPb) collisions at root S-NN = 5.02 TeV when compared at the same centrality (i.e., the same fraction of total cross section). However, the XeXe suppression is slightly greater than that for PbPb in events having a similar number of participating nucleons.
Citation - WoS: 36
Citation - Scopus: 125
Coherent J/? Photoproduction in Ultra-Peripheral Pbpb Collisions at Snn=2.76tev With the Cms Experiment
(Elsevier Ltd., 2017-09) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
The cross section for coherent J/ψ photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, Xn0n, is measured with the CMS experiment in ultra-peripheral PbPb collisions at sNN=2.76TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 159μb−1, collected during the 2011 PbPb run. The J/ψ mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is dσXn0n coh/dy(J/ψ)=0.36±0.04(stat)±0.04(syst) mb in the rapidity interval 1.8<|y|<2.3. Using a model for the relative rate of coherent photoproduction processes, this Xn0n measurement gives a total coherent photoproduction cross section of dσcoh/dy(J/ψ)=1.82±0.22(stat)±0.20(syst)±0.19(theo) mb. The data strongly disfavor the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent J/ψ photoproduction in γ+Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.
Citation - WoS: 29
Citation - Scopus: 36
Combination of Cms Searches for Heavy Resonances Decaying To Pairs of Bosons or Leptons
(Elsevier B.V., 2019) Sirunyan, A.M.; Karapınar, Güler; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Cerrada, M.; 01. Izmir Institute of Technology
A statistical combination of searches for heavy resonances decaying to pairs of bosons or leptons is presented. The data correspond to an integrated luminosity of 35.9 fb−1 collected during 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data are found to be consistent with expectations from the standard model background. Exclusion limits are set in the context of models of spin-1 heavy vector triplets and of spin-2 bulk gravitons. For mass-degenerate W′ and Z′ resonances that predominantly couple to the standard model gauge bosons, the mass exclusion at 95% confidence level of heavy vector bosons is extended to 4.5 TeV as compared to 3.8 TeV determined from the best individual channel. This excluded mass increases to 5.0 TeV if the resonances couple predominantly to fermions. © 2019 The Author(s)
Citation - WoS: 31
Citation - Scopus: 22
Combination of Inclusive and Differential Tt¯ Charge Asymmetry Measurements Using Atlas and Cms Data at ?s = 7 and 8 Tev
(Springer Verlag, 2018-01) CMS Collaboration; Karapınar, Güler; ATLAS Collaboration; Karapınar, Güler; 01. Izmir Institute of Technology
This paper presents combinations of inclusive and differential measurements of the charge asymmetry (AC) in top quark pair (tt) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centreof- mass energies of 7 and 8TeV. The data correspond to integrated luminosities of about 5 and 20 fb–1for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are AC LHC7= 0:005±0:007 (stat) ±0:006 (syst) at 7TeV and AC LHC7= 0:0055 ± 0:0023 (stat) ± 0:0025 (syst) at 8TeV. These values, as well as the combination of AC measurements as a function of the invariant mass of the [formula presented] system at 8TeV, are consistent with the respective standard model predictions.
Citation - WoS: 36
Citation - Scopus: 36
Combination of Searches for Heavy Resonances Decaying To Ww, Wz, Zz, Wh, and Zh Boson Pairs in Proton-Proton Collisions at Root S=8 and 13 Tev
(Elsevier Ltd., 2017) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of Technology
A statistical combination of searches is presented for massive resonances decaying to WW, WZ, ZZ, WH, and ZH boson pairs in proton-proton collision data collected by the CMS experiment at the LHC. The data were taken at centre-of-mass energies of 8 and 13TeV, corresponding to respective integrated luminosities of 19.7 and up to 2.7 fb(-1). The results are interpreted in the context of heavy vector triplet and singlet models that mimic properties of composite-Higgs models predicting W' and Z' bosons decaying to WZ, WW, WH, and ZH bosons. A model with a bulk graviton that decays into WW and ZZ is also considered. This is the first combined search for WW, WZ, WH, and ZH resonances and yields lower limits on masses at 95% confidence level for W' and Z' singlets at 2.3 TeV, and for a triplet at 2.4TeV. The limits on the production cross section of a narrow bulk graviton resonance with the curvature scale of the warped extra dimension (K)over-tilde = 0.5, in the mass range of 0.6 to 4.0TeV, are the most stringent published to date. (c) 2017 The Author(s). Published by Elsevier B.V.
Citation - WoS: 56
Citation - Scopus: 144
Combination of Searches for Higgs Boson Pair Production in Proton-Proton Collisions at Root S=13 Tev
(American Physical Society, 2019) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of Technology
This Letter describes a search for Higgs boson pair production using the combined results from four final states: bb gamma gamma, bb tau tau, bbbb, and bbVV, where V represents a W or Z boson. The search is performed using data collected in 2016 by the CMS experiment from LHC proton-proton collisions at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). Limits are set on the Higgs boson pair production cross section. A 95% confidence level observed (expected) upper limit on the non-resonant production cross section is set at 22.2 (12.8) times the standard model value. A search for narrow resonances decaying to Higgs boson pairs is also performed in the mass range 250-3000 GeV. No evidence for a signal is observed, and upper limits are set on the resonance production cross section.
Citation - WoS: 25
Citation - Scopus: 33
Combination of the W Boson Polarization Measurements in Top Quark Decays Using Atlas and Cms Data at Root S=8 Tev
(Springer Verlag, 2020) Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb(-1)for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal (F-0), left-handed (F-L), or right-handed (F-R) polarizations. The resulting combined measurements of the polarization fractions are F-0= 0.693 +/- 0.014 and F-L= 0.315 +/- 0.011. The fractionF(R)is calculated from the unitarity constraint to be F-R=-0.008 +/- 0.007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F-0(F-L) with respect to the most precise single measurement. A limit on anomalous right-handed vector (V-R), and left- and right-handed tensor (g(L), g(R)) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [-0.11,0.16] for V-R, [-0.08,0.05] for g(L), and [-0.04,0.02] for g(R), at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived.
Citation - WoS: 53
Citation - Scopus: 32
Combinations of Single-Top Production Cross-Section Measurements and Vertical Bar F(lv)v(tb)vertical Bar Determinations at Root S=7 and 8 Tev With the Atlas and Cms Experiments
(Springer Verlag, 2019) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of Technology
This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb(-1) at = 7 TeV and 12.2 to 20.3 fb(-1) at = 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 +/- 5.7 pb and 87.7 +/- 5.8 pb at = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 +/- 4.1 pb and 23.1 +/- 3.6 pb at = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 +/- 1.4 pb at = 8 TeV. The square of the magnitude of the CKM matrix element V-tb multiplied by a form factor f(LV) is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |V-td|, |V-ts| << |V-tb|. All the |f(LV)V(tb)|(2) determinations, extracted from individual ratios at = 7 and 8 TeV, are combined, resulting in |f(LV)V(tb)| = 1.02 +/- 0.04 (meas.) +/- 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.
Citation - WoS: 669
Citation - Scopus: 1166
Combined Measurement of the Higgs Boson Mass in Pp Collisions at Root S=7 and 8 Tev With the Atlas and Cms Experiments
(American Physical Society, 2015) Aad, G.; Karapınar, Güler; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; Sosa, D.; Karapınar, Güler; 01. Izmir Institute of Technology
A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the H --> gamma gamma and H --> ZZ --> 4l decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is m(H) = 125.09 +/- 0.21 (stat) +/- 0.11 (syst) GeV.
Citation - WoS: 27
Citation - Scopus: 47
Combined Search for Anomalous Pseudoscalar Hvv Couplings in Vh(h?bb?) Production and Hh?vv Decay
(Elsevier Ltd., 2016-08) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
A search for anomalous pseudoscalar couplings of the Higgs boson H to electroweak vector bosons V (=W or Z) in a sample of proton–proton collision events corresponding to an integrated luminosity of 18.9 fb−1 at a center-of-mass energy of 8 TeV is presented. Events consistent with the topology of associated VH production, where the Higgs boson decays to a pair of bottom quarks and the vector boson decays leptonically, are analyzed. The consistency of data with a potential pseudoscalar contribution to the HVV interaction, expressed by the effective pseudoscalar cross section fractions fa3, is assessed by means of profile likelihood scans. Results are given for the VH channels alone and for a combined analysis of the VH and previously published H→VV channels. Under certain assumptions, fa3ZZ>0.0034 is excluded at 95% confidence level in the combination. Scenarios in which these assumptions are relaxed are also considered.
Citation - WoS: 70
Citation - Scopus: 123
Combined Search for Electroweak Production of Charginos and Neutralinos in Proton-Proton Collisions at ?s=13 Tev
(Springer Verlag, 2018-03) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of Technology
A statistical combination of several searches for the electroweak production of charginos and neutralinos is presented. All searches use proton-proton collision data at s=13 TeV, recorded with the CMS detector at the LHC in 2016 and corresponding to an integrated luminosity of 35.9 fb−1. In addition to the combination of previous searches, a targeted analysis requiring three or more charged leptons (electrons or muons) is presented, focusing on the challenging scenario in which the difference in mass between the two least massive neutralinos is approximately equal to the mass of the Z boson. The results are interpreted in simplified models of chargino-neutralino or neutralino pair production. For chargino-neutralino production, in the case when the lightest neutralino is massless, the combination yields an observed (expected) limit at the 95% confidence level on the chargino mass of up to 650 (570) GeV, improving upon the individual analysis limits by up to 40 GeV. If the mass difference between the two least massive neutralinos is approximately equal to the mass of the Z boson in the chargino-neutralino model, the targeted search requiring three or more leptons obtains observed and expected exclusion limits of around 225 GeV on the second neutralino mass and 125 GeV on the lightest neutralino mass, improving the observed limit by about 60 GeV in both masses compared to the previous CMS result. In the neutralino pair production model, the combined observed (expected) exclusion limit on the neutralino mass extends up to 650–750 (550–750) GeV, depending on the branching fraction assumed. This extends the observed exclusion achieved in the individual analyses by up to 200 GeV. The combined result additionally excludes some intermediate gaps in the mass coverage of the individual analyses.

Browse

Browsing Rectorate / Rektörlük by WoS Q "Q1"