WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Numerical Investigation of a Time-Modulated Lorentz-Dispersive Bianisotropic Metasurface for Nonreciprocal Transmission and Absorption(American Physical Society, 2025) Yilmaz, Hasan OnderThis work presents a numerical framework for modeling and solving time-modulated responses of complex bianisotropic metasurfaces. First, Lorentz-dispersive surfaces are implemented as impedance sheet models for the surface-wave-assisted transmissive bianisotropic metasurface, and the results are validated with prior analytical solutions. Next, a finite-difference time-domain (FDTD)-based numerical solution for time-modulated media is developed within the MIT Electromagnetic Equation Propagation (meep) framework using a sampled time-varying material function approach, and is verified through comparisons with circuit-based numerical methods, analytical solutions, and a reference FDTD solver. The results show good agreement in terms of harmonic frequencies, power levels, and phase-coherent transmission response. The method is then applied to simulate the time-modulated metasurface modeled with Lorentz-dispersive multilayers, demonstrating nonreciprocal transmission and unidirectional absorption under relatively low-frequency modulation. The proposed numerical approaches offer efficient and practical frameworks for modeling complex electromagnetic media in the time domain and for performing dynamic full-wave simulations, providing a viable solution path for analyzing functionalities such as isolation, unidirectional amplification, and absorption-phenomena that are difficult to achieve in time-invariant systems.Article Citation - WoS: 1Computational Investigation of Electronic, Vibrational, and Transport Properties of Silicon Phosphide Nanoribbons(American Physical Society, 2025) Sargin, G.Ö.; Jahangirzadeh Varjovi, M.J.; Ozbey, D.H.; Sevinçli, H.; Durgun, E.Two-dimensional (2D) silicon phosphide (SiP) has recently emerged as a promising semiconductor for electronic, optoelectronic, and thermoelectric applications due to its unique electronic and structural characteristics. One-dimensional (1D) nanoribbons (NRs) derived from 2D SiP offer a versatile and scalable platform for device miniaturization and performance enhancement in nanoelectronics. Motivated by their potential, we present a comprehensive first-principles investigation of the structural, electronic, dynamical, and electronic transport properties of SiP-NRs. Specifically, we focus on both bare and hydrogen-passivated armchair (A-NRs, HA-NRs) and zigzag (Z-NRs, HZ-NRs) configurations. Our results reveal that hydrogen passivation effectively suppresses edge reconstructions observed in bare SiP-NRs, thus dynamically stabilizing their structures. Analysis of electronic band structures demonstrates a clear width-dependent oscillatory behavior of the band gap in bare A-NRs, which diminishes significantly upon hydrogen termination. The width-scaled electronic conductance (G<inf>e</inf>ws) of HA-NRs exhibits a decreasing trend with increasing ribbon width, featuring distinct even-odd oscillations for n-type transport due to subband splitting effects. In contrast, HZ-NRs display notable deviations in p-type conductance from their 2D SiP counterpart, particularly at low temperatures (around 100 K), arising from residual localized edge states. However, with increasing width and temperature, transport behavior converges toward that of 2D SiP monolayers, indicating diminishing edge effects. Unlike their p-type counterparts, the n-type G<inf>e</inf> values of the largest HA-NRs and HZ-NRs increase with the square root of temperature, similar to the n-type conductance trend observed in 2D SiP. This behavior is attributed to the evolution of the electronic transmission function (τ(E)) from a steplike profile in narrow ribbons to an E1/2 dependence in wider ribbons, analogous to the 2D counterpart. These findings highlight the significant influence of width and edge termination on the transport characteristics of SiP-NRs and underline their potential as fundamental building blocks for high-performance nanoelectronic and thermoelectric quasi-1D devices. © 2025 authors. Published by the American Physical Society.Article Citation - WoS: 5Citation - Scopus: 9Search for Resonances Decaying To Three W Bosons in Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2022) Karapınar, Güler; CMS CollaborationA search for resonances decaying into a W boson and a radion, where the radion decays into two W bosons, is presented. The data analyzed correspond to an integrated luminosity of 138 fb???1 recorded in ffiffiproton-proton collisions with the CMS detector at p s 1/4 13 TeV. One isolated charged lepton is required, together with missing transverse momentum and one or two massive large-radius jets, containing the decay products of either two or one W bosons, respectively. No excess over the background estimation is observed. The results are combined with those from a complementary channel with an all-hadronic final state, described in an accompanying paper. Limits are set on parameters of an extended warped extradimensional model. These searches are the first of their kind at the LHC.Article Citation - WoS: 25Citation - Scopus: 32Using Z Boson Events To Study Parton-Medium Interactions in Pb-Pb Collisions(American Physical Society, 2022) Karapınar, GülerThe spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson arc reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7 nb(-1) and 320 pb(-1), respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum p(T) > 30 GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and p(T) spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables.Article Citation - WoS: 35Citation - Scopus: 41Search for Heavy Resonances Decaying To Ww, Wz, or Wh Boson Pairs in a Final State Consisting of a Lepton and a Large-Radius Jet in Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2022) Karapınar, GülerA search for new heavy resonances decaying to pairs of bosons (WW, WZ, or WH) is presented. The analysis uses data from proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb(-1). One of the bosons is required to be a W boson decaying to an electron or muon and a neutrino, while the other boson is required to be reconstructed as a single jet with mass and substructure compatible with a quark pair from a W, Z, or Higgs boson decay. The search is performed in the resonance mass range between 1.0 and 4.5 TeVand includes a specific search for resonances produced via vector boson fusion. The signal is extracted using a twodimensional maximum likelihood fit to the jet mass and the diboson invariant mass distributions. No significant excess is observed above the estimated background. Model-independent upper limits on the production cross sections of spin-0, spin-1, and spin-2 heavy resonances are derived as functions of the resonance mass and are interpreted in the context of bulk radion, heavy vector triplet, and bulk graviton models. The reported bounds are the most stringent to date.Article Citation - WoS: 64Citation - Scopus: 70Measurement of Differential T(t)over-Bar Production Cross Sections in the Full Kinematic Range Using Lepton Plus Jets Events From Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2021) Karapınar, Güler; CMS CollaborationMeasurements of differential and double-differential cross sections of top-quark pair (t (t) over bar) production arc presented in the lepton + jets channels with a single electron or muon and jets in the final state. The analysis combines for the first time signatures of top quarks with low transverse momentum p(T), where the top-quark decay products can be identified as separated jets and isolated leptons, and with high p(T), where the decay products are collimated and overlap. The measurements arc based on proton-proton collision data at is - = 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 137 fb(-1). The cross sections are presented at the parton and particle levels, where the latter minimizes extrapolations based on theoretical assumptions. Most of the measured differential cross sections are well described by standard model predictions with the exception of some double-differential distributions. The inclusive t (t) over bar production cross section is measured to be sigma(t (t) over bar) = 791 +/- 25 pb, which constitutes the most precise measurement in the lepton + jets channel to date.Article Citation - WoS: 47Search for Heavy Neutrinos and W-R Bosons With Right-Handed Couplings in a Left-Right Symmetric Model in Pp Collisions at Root S=7 Tev(American Physical Society, 2012) Karapınar, GülerResults are presented from a search for heavy, right-handed muon neutrinos, N-mu, and right-handed W-R bosons, which arise in the left-right symmetric extensions of the standard model. The analysis is based on a 5: 0 fb(-1) sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected by the CMS detector at the Large Hadron Collider. No evidence is observed for an excess of events over the standard model expectation. For models with exact left-right symmetry, heavy right-handed neutrinos are excluded at 95% confidence level for a range of neutrino masses below the WR mass, dependent on the value of M-WR. The excluded region in the two-dimensional (M-WR, MN mu) mass plane extends to M-WR = 2.5TeV. DOI: 10.1103/PhysRevLett.109.261802Article Citation - WoS: 13Search for Supersymmetry in Events With Opposite-Sign Dileptons and Missing Transverse Energy Using an Artificial Neural Network(American Physical Society, 2013) Karapınar, GülerIn this paper, a search for supersymmetry (SUSY) is presented in events with two opposite-sign isolated leptons in the final state, accompanied by hadronic jets and missing transverse energy. An artificial neural network is employed to discriminate possible SUSY signals from a standard model background. The analysis uses a data sample collected with the CMS detector during the 2011 LHC run, corresponding to an integrated luminosity of 4: 98 fb(-1) of proton-proton collisions at the center-of-mass energy of 7 TeV. Compared to other CMS analyses, this one uses relaxed criteria on missing transverse energy (E-T > 40 GeV) and total hadronic transverse energy (HT > 120 GeV), thus probing different regions of parameter space. Agreement is found between standard model expectation and observations, yielding limits in the context of the constrained minimal supersymmetric standard model and on a set of simplified models. DOI: 10.1103/PhysRevD.87.072001Article Citation - WoS: 19Search for Z ' Resonances Decaying To T(t)over-Bar in Dilepton Plus Jets Final States in Pp Collisions at Root S=7 Tev(American Physical Society, 2013) Karapınar, GülerA search for resonances decaying to top quark-antiquark pairs is performed using a dilepton + jets data sample recorded by the CMS experiment at the LHC in pp collisions at root s = 7 TeV corresponding to an integrated luminosity of 5.0 fb(-1). No significant deviations from the standard model background are observed. Upper limits are presented for the production cross section times branching fraction of top quark-antiquark resonances for masses from 750 to 3000 GeV. In particular, the existence of a leptophobic topcolor particle Z' is excluded at the 95% confidence level for resonance masses M-Z' < 1.3 TeV for Gamma(Z') = 0.012M(Z'), and M < 1.9 TeV for Gamma(Z') = 0.10M(Z'). DOI: 10.1103/PhysRevD.87.072002Article Citation - WoS: 48Search for Pair-Produced Dijet Resonances in Four-Jet Final States in Pp Collisions at Root S=7 Tev(American Physical Society, 2013) Karapınar, GülerA search for the pair production of a heavy, narrow resonance decaying into two jets has been performed using events collected in root s = 7 TeV pp collisions with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5.0 fb(-1). Events are selected with at least four jets and two dijet combinations with similar dijet mass. No resonances are found in the dijet mass spectrum. The upper limit at 95% confidence level on the product of the resonance pair production cross section, the branching fractions into dijets, and the acceptance varies from 0.22 to 0.005 pb, for resonance masses between 250 and 1200 GeV. Pair-produced colorons decaying into q (q) over bar are excluded for coloron masses between 250 and 740 GeV. DOI:10.1103/PhysRevLett.110.141802