Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
- Publication Year
- Publication
- Publication Type
Articles 61 - 90 of 550
Full-Text Articles in Physical Sciences and Mathematics
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
Dissertations, Theses, and Masters Projects
Upon cooling past a critical temperature Tc = 340 K Vanadium dioxide (VO2) exhibits a metal-insulator transition (MIT) from a metallic rutile R to an insulating monoclinic M1 phase. Other insulating phases, a monoclinic M2 and triclinic T, have been identifed and are accessible via strain or doping. Despite decades of research, the nature of the VO2 MIT is still not fully understood. In this work we present ab-initio hybrid density functional theory (DFT) calculations on the insulating phases, compare the results to experimental measurements and discuss their implications on our understanding of the VO2 MIT. Recent measurements on M1 …
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Dissertations, Theses, and Masters Projects
In this thesis we investigate the phenomenology of beyond the Standard Model scenarios with extra scalar fields. A review and motivation of extended electroweak symmetry breaking is presented. Then we address observational evidence of new physics such as possible lepton flavor violating processes and the relic abundance of dark matter by implementing models with three Higgs doublets. The complementarity between theoretical restrictions and experimental bounds on some of the predicted signals is leveraged to sharpen the allowed parameter space. After that we study embeddings of two-Higgs doublets into the Randall-Sundrum model with emphasis on the scalar fluctuations of the metric …
Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati
Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati
Dissertations, Theses, and Masters Projects
Multi-photon nonlinear processes in atoms have served as important tools for quantum metrology, quantum communications, and quantum sensing. In this thesis, we experimentally address the interplay of various multi-photon Raman processes in hot Rb vapor, with the four-wave mixing (FWM) process being a central theme. FWM is the nonlinear response of a medium to a strong optical pump field inelastically scattering off atomic resonances and resulting in the generation of additional photons in different modes. FWM is a detrimental, but inherent part of electromagnetically induced transparency (EIT) and Raman based quantum memories. However, we were able to weaken the four-photon …
Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden
Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden
Dissertations, Theses, and Masters Projects
There is a need for efficient ultraviolet (UV) detectors in many fields, such as aerospace, automotive manufacturing, biology, environmental science, and defense, due to photomultiplier tubes (the currently available technology) often not meeting application constraints in weight, robustness, and power consumption. In my thesis, I demonstrate that high quality vanadium dioxide (VO2) thin films, epitaxially grown on niobium doped titanium dioxide substrates (TiO2:Nb), display a strong photoconductive response in the UV spectral range, making them promising candidates for photomultiplier-free UV photodetection. By adjusting the characteristics of the substrate and VO2 film, the samples achieve external quantum efficiency exceeding 100% (reaching …
Spatial Multiplexing Of Squeezed Light By Coherence Diffusion, Jian Sun, (...), Eugeniy E. Mikhailov, Irina Novikova, Et Al.
Spatial Multiplexing Of Squeezed Light By Coherence Diffusion, Jian Sun, (...), Eugeniy E. Mikhailov, Irina Novikova, Et Al.
Arts & Sciences Articles
Spatially splitting nonclassical light beams is in principle prohibited due to noise contamination during beam splitting. We propose a platform based on thermal motion of atoms to realize spatial multiplexing of squeezed light. Light channels of separate spatial modes in an antirelaxation coated vapor cell share the same long-lived atomic coherence jointly created by all channels through the coherent diffusion of atoms, which in turn enhances the individual channel’s nonlinear process responsible for light squeezing. Consequently, it behaves as squeezed light in one optical channel transferring to other distant channels even with laser powers below the threshold for squeezed light …
Second-Order Dirac Superconductors And Magnetic Field Induced Majorana Hinge Modes, Sayed Ali Akbar Ghorashi, Xiang Hu, Taylor L. Hughes, Enrico Rossi
Second-Order Dirac Superconductors And Magnetic Field Induced Majorana Hinge Modes, Sayed Ali Akbar Ghorashi, Xiang Hu, Taylor L. Hughes, Enrico Rossi
Arts & Sciences Articles
We identify three-dimensional higher-order superconductors characterized by the coexistence of one-dimensional Majorana hinge states and gapless surface states. We show how such superconductors can be obtained starting from the model of a spinful quadrupolar semimetal with two orbitals and adding an s-wave superconducting pairing term. By considering all the possible s-wave pairings satisfying Fermi-Dirac statistics we obtain six different superconducting models. We find that for two of these models a flat band of hinge Majorana states coexist with surface states, and that these models have a nonvanishing quadrupolelike topological invariant. Two of the other models, in the presence of a …
Topics In Proton Structure: Bsm Answers To Its Radius Puzzle And Lattice Subtleties Within Its Momentum Distribution, Michael Chaim Freid
Topics In Proton Structure: Bsm Answers To Its Radius Puzzle And Lattice Subtleties Within Its Momentum Distribution, Michael Chaim Freid
Dissertations, Theses, and Masters Projects
This thesis covers two subjects, briefly outlined below, of hadronic physics. The proton radius puzzle and the muon anomalous magnetic moment discrepancy point to possible signs of lepton-universality violation. We introduce the context and background necessary to understand these two problems. And we analyze two suitable beyond-the-standard-model solutions, one vector-based and one scalar-based, which simultaneously solves both issues. Furthermore, we demonstrate that the parameter space of the respective solutions can be chosen so as to not be completely forbidden by considered experimental constraints. Specifically, we show that certain violations, analyzed by other authors in the context of similar solutions to …
Scattering A Bose-Einstein Condensate Off A Modulated Barrier, Andrew James Pyle
Scattering A Bose-Einstein Condensate Off A Modulated Barrier, Andrew James Pyle
Dissertations, Theses, and Masters Projects
A quantum pump is a device that transports particles through a circuit with localized time-varying potentials, and without the need for an external applied voltage or chemical potential. Quantum pumping was originally proposed in the context of electron transport in nanowires, but has proven difficult to implement. The ultracold atom approach represents a possible route around the current experimental bottleneck. We present an experiment to study 1D quantum mechanical scattering by an amplitude-modulated barrier. This experiment represents a first step toward implementing a quantum pump for ultracold atoms based on two such barriers modulated out of phase with one another. …
Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus
Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus
Dissertations, Theses, and Masters Projects
By mining data from Jefferson Lab Hall A experiment E08-014 a new measurement of the 3He elastic cross section at Q^2 ≈ 34 fm^−2 was extracted from a large quasielastic background. This new data point falls approximately halfway between the first and second diffractive minima of the 3He form factors. When combined with recent high Q^2 3He elastic cross section measurements from JLab this new point improves our knowledge of the cross section and form factors at large momentum transfers. The new high Q^2 data motivate a reanalysis of the 3He elastic cross section world data and promise an improved …
Beyond The Standard Model: Flavor Symmetry, Nonperturbative Unification, Quantum Gravity, And Dark Matter, Shikha Chaurasia
Beyond The Standard Model: Flavor Symmetry, Nonperturbative Unification, Quantum Gravity, And Dark Matter, Shikha Chaurasia
Dissertations, Theses, and Masters Projects
Despite the vast success of the Standard Model of particle physics, it is no secret that is also has its shortcomings, thus providing incentive to look beyond the Standard Model for solutions. In this thesis we focus in particular on a model of horizontal flavor symmetry, unification via a universal Landau pole, emergent gravity, and dark matter. First we explain the observed hierarchies in the elementary fermion mass spectrum via a model based on the double tetrahedral group, the smallest discrete subgroup of SU(2), while relaxing previous assumptions of supersymmetry. A sequential symmetry breaking process results in a hierarchy in …
Electronic Properties Of Two-Dimensional Van Der Waals Systems, Yohanes Satrio Gani
Electronic Properties Of Two-Dimensional Van Der Waals Systems, Yohanes Satrio Gani
Dissertations, Theses, and Masters Projects
In this dissertation we study the electronic structure of van der Waals systems. A van der Waals systems is a heterostructure in which the different constituents are held together by van der Waals forces. We study two different types of van der Waals systems: van der Waals systems formed by graphene and a monolayer of NbSe2, van der Waals systems obtained by placing graphene nanoribbons on a two-dimensional crystal. For the first type of systems we build a continuous low-energy effective model that takes into account the presence of a twist angle between graphene and NbSe2, and of spin-orbit coupling …
Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson
Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson
Dissertations, Theses, and Masters Projects
Two-dimensional (2D) materials, including graphene and graphene oxide (GO), are a subject of interest for many researchers due to their exceptional properties (strength, conductivity, etc.). These materials, comprised of atomically-thin sheets, may naturally occur stacked together like sheets of paper, but their most interesting properties emerge when separated into individual layers. However, scaling up the processes used to isolate single sheets of some of these materials, particularly graphene, has proven problematic. They can be fiercely resistant to exfoliation, difficult to disperse, and have a worrying propensity to restack. All these problems contribute to the great difficulty these fascinating materials have …
Global Shipping Container Monitoring Using Machine Learning With Multi-Sensor Hubs And Catadioptric Imaging, Victor Esteban Trujillo
Global Shipping Container Monitoring Using Machine Learning With Multi-Sensor Hubs And Catadioptric Imaging, Victor Esteban Trujillo
Dissertations, Theses, and Masters Projects
We describe a framework for global shipping container monitoring using machine learning with multi-sensor hubs and infrared catadioptric imaging. A wireless mesh radio satellite tag architecture provides connectivity anywhere in the world which is a significant improvement to legacy methods. We discuss the design and testing of a low-cost long-wave infrared catadioptric imaging device and multi-sensor hub combination as an intelligent edge computing system that, when equipped with physics-based machine learning algorithms, can interpret the scene inside a shipping container to make efficient use of expensive communications bandwidth. The histogram of oriented gradients and T-channel (HOG+) feature as introduced for …
Strong Electron-Boson Coupling In The Iron-Based Superconductor Bafe1.9pt0.1as2 Revealed By Infrared Spectroscopy, Zhen Xing, Shanta Saha, J. Paglione, M. M. Qazilbash
Strong Electron-Boson Coupling In The Iron-Based Superconductor Bafe1.9pt0.1as2 Revealed By Infrared Spectroscopy, Zhen Xing, Shanta Saha, J. Paglione, M. M. Qazilbash
Arts & Sciences Articles
Understanding the formation of Cooper pairs in iron-based superconductors is one of the most important topics in condensed matter physics. In conventional superconductors, the electron-phonon interaction leads to the formation of Cooper pairs. In conventional strong-coupling superconductors like lead (Pb), the features due to electron-phonon interaction are evident in the infrared absorption spectra. Here we investigate the infrared absorption spectra of the iron arsenide superconductor BaFe1.9Pt0.1As2. We find that this superconductor has fully gapped (nodeless) Fermi surfaces, and we observe the strong-coupling electron-boson interaction features in the infrared absorption spectra. Through modeling with the Eliashberg function based on Eliashberg theory, …
Probe Of Electroweak Interference Effects In Non-Resonant Inelastic Electron-Proton Scattering, James Franklyn Dowd
Probe Of Electroweak Interference Effects In Non-Resonant Inelastic Electron-Proton Scattering, James Franklyn Dowd
Dissertations, Theses, and Masters Projects
The Qweak collaboration at Jefferson Lab made the first direct measurement of the proton's weak charge, Q_W^p, via a measurement of the parity-violating asymmetry in elastic e ⃑p scattering with low four-momentum transfer. to meet the high-precision goals, energy-dependent electroweak radiative corrections were applied to the measured asymmetry. The γZ box, □_γZ, where a photon and a Z-boson are simultaneously exchanged, was the most problematic of these corrections. It could not be calculated through the same perturbative methods as the rest of the corrections. The □_γZ correction depends on theoretical models of the γZ interference structure functions, F_1,2^γZ, for which …
Exotic Phases In Attractive Fermions: Charge Order, Pairing, And Topological Signatures, Peter Rosenberg
Exotic Phases In Attractive Fermions: Charge Order, Pairing, And Topological Signatures, Peter Rosenberg
Dissertations, Theses, and Masters Projects
Strongly interacting many-body systems remain a central challenge of modern physics. Recent developments in the field of ultra-cold atomic physics have opened a new window onto this enduring problem. Experimental progress has revolutionized the approach to studying many-body systems and the exotic behaviors that emerge in these systems. It is now possible to engineer and directly measure a variety of models that can capture the essential features of real materials without the added complexity of disorder, impurities, or complicated or irregular geometries. The parameters of these models can be freely tuned with tremendous precision. These experimental realizations are an ideal …
A Measurement Of Nuclear Effects In Deep Inelastic Scattering In Neutrino-Nucleus Interactions, Anne Norrick
A Measurement Of Nuclear Effects In Deep Inelastic Scattering In Neutrino-Nucleus Interactions, Anne Norrick
Dissertations, Theses, and Masters Projects
Neutrino-Nucleus Deep Inelastic Scattering (DIS) events provide a probe into the structure of nucleons within a nucleus that cannot be accessed via charged lepton-nucleus interactions. The MINERvA experiment is stationed in the Neutrinos from the Main Injector (NuMI) beam line at Fermi National Accelerator Laboratory. With the recent increase in average neutrino energy and the greatly increased intensity of the NuMI beam line, projected sensitivities for DIS cross section ratio analyses using MINERvA's suite of nuclear targets (C, CH, Fe and Pb) are greatly increased. an analysis of theMINERvA DIS data on carbon, iron, lead, and plastic has been conducted …
Dynamics Of Systems With Hamiltonian Monodromy, Daniel Salmon
Dynamics Of Systems With Hamiltonian Monodromy, Daniel Salmon
Dissertations, Theses, and Masters Projects
A system is said to have monodromy if, when we carry the system around a closed circuit, it does not return to its initial state. The simplest example is the square-root function in the complex plane. A Hamiltonian system is said to have Hamiltonian monodromy if its fundamental action-angle loops do not return to their initial topological state at the end of a closed circuit. These changes in topology of angle loops carry through to other aspects of these systems, including the classical dynamics of families of trajectories, quantum spectra and even wavefunctions. This topological change in the evolution of …
Extensions Of The Standard Model Higgs Sector, Richard Keith Thrasher
Extensions Of The Standard Model Higgs Sector, Richard Keith Thrasher
Dissertations, Theses, and Masters Projects
The Standard Model is regarded as one of the most successful scientific theories, but there is compelling evidence that it is an incomplete theory of particle physics. There is currently no understanding of the observed baryon asymmetry, the nature of dark matter, and dark energy. Field theoretic considerations indicate parameters in the Standard Model are extremely fine-tuned. This suggests the existence of new physics, accessible at higher energies, to explain these seemingly unnatural tunings. to solve these puzzles, and others not addressed by the Standard Model, many extensions of the Standard Model have been proposed. It is of great importance …
Topological Changes Of Wave Functions Associated With Hamiltonian Monodromy, C. Chen, John B. Delos
Topological Changes Of Wave Functions Associated With Hamiltonian Monodromy, C. Chen, John B. Delos
Arts & Sciences Articles
Almost everything that happens in classical mechanics also shows up in quantum mechanics when we know where to look for it. A phenomenon in classical mechanics involves topological changes in action-angle loops as a result of passage around a “monodromy circuit.” This phenomenon is known by the short name “Hamiltonian monodromy” (or, more ponderously, “nontrivial monodromy of action and angle variables in integrable Hamiltonian systems”). In this paper, we show a corresponding change in quantum wave functions: These wave functions change their topological structure in the same way that the corresponding classical action-angle loops change.
Isotope Shifts In The 7 S → 8 S Transition Of Francium: Measurements And Comparison To Ab Initio Theory, M. R. Kalita, J. A. Behr, (...), Seth Aubin, Et Al.
Isotope Shifts In The 7 S → 8 S Transition Of Francium: Measurements And Comparison To Ab Initio Theory, M. R. Kalita, J. A. Behr, (...), Seth Aubin, Et Al.
Arts & Sciences Articles
We observe the electric-dipole forbidden 7s→8s transition in the francium isotopes 208−211Fr and 213Fr using a two-photon excitation scheme. We collect the atoms online from an accelerator and confine them in a magneto-optical trap for the measurements. In combination with previous measurements of the 7s→7p1/2 transition we perform a King plot analysis. We compare the thus-determined ratio of the field shift constants (1.228 ± 0.019) to results obtained from new ab initio calculations (1.234 ± 0.010).
Microwave Ac Zeeman Force For Ultracold Atoms, C. T. Fancher, A. J. Pyle, A. P. Rotunno, Seth Aubin
Microwave Ac Zeeman Force For Ultracold Atoms, C. T. Fancher, A. J. Pyle, A. P. Rotunno, Seth Aubin
Arts & Sciences Articles
We measure the ac Zeeman force on an ultracold gas of 87Rb due to a microwave magnetic field targeted to the 6.8 GHz hyperfine splitting of these atoms. An atom chip produces a microwave near field with a strong amplitude gradient, and we observe a force over three times the strength of gravity. Our measurements are consistent with a simple two-level theory for the ac Zeeman effect and demonstrate its resonant, bipolar, and spin-dependent nature. We observe that the dressed-atom eigenstates gradually mix over time and have mapped out this behavior as a function of magnetic field and detuning. We …
Cosmogenic Neutron Production At Daya Bay, Daya Bay Collaboration, (…), R. D. Mckeown, W. Wang, Et Al.
Cosmogenic Neutron Production At Daya Bay, Daya Bay Collaboration, (…), R. D. Mckeown, W. Wang, Et Al.
Arts & Sciences Articles
Neutrons produced by cosmic ray muons are an important background for underground experiments studying neutrino oscillations, neutrinoless double beta decay, dark matter, and other rare-event signals. A measurement of the neutron yield in the three different experimental halls of the Daya Bay Reactor Neutrino Experiment at varying depth is reported. The neutron yield in Daya Bay's liquid scintillator is measured to be Y-n = (10.26 +/- 0.86) x 10(-5), (10.22 +/- 0.87) x 10(-5), and (17.03 +/- 1.22) x 10(-5) mu(-1)g(-1)cm(2) at depths of 250, 265, and 860 meters-water-equivalent. These results are compared to other measurements and the simulated neutron …
Searching For A Dark Photon In The Hps Experiment, Sebouh Jacob Paul
Searching For A Dark Photon In The Hps Experiment, Sebouh Jacob Paul
Dissertations, Theses, and Masters Projects
The Heavy Photon Search (HPS) experiment at Jefferson Lab is designed to search for a hypothesized elementary particle called a dark (heavy) photon. Such a particle would behave as a mediator between dark matter and the Standard Model through a kinetic mixing with the Standard Model’s photon. The search is performed by scattering GeV-scale electrons off tungsten nuclei in a fixed target and looking for a resonance and/or displaced vertices amidst a background of radiative QED trident events. These background events are kinematically identical to the events in which dark photons are produced and decay into lepton pairs. Several other …
Proton Spin Structure From Monte Carlo Global Qcd Analyses, Jacob Ethier
Proton Spin Structure From Monte Carlo Global Qcd Analyses, Jacob Ethier
Dissertations, Theses, and Masters Projects
Although significant progress has been made in recent years in understanding the composition of the proton's spin from its quark and gluon constituents, a complete picture has yet to emerge. Such information is encoded in spin-dependent parton distribution functions (PDFs) that, as a consequence of being inherently nonperturbative, must be extracted through global QCD analyses of polarized lepton-nucleon and proton-proton collisions. Experiments that measure a final state hadron from these reactions are particularly useful for separating the individual quark and anti-quark polarizations, but require knowledge of parton-to-hadron fragmentation functions (FFs) to describe theoretically. In this thesis, we present a new …
Experimental Observation Of Classical Dynamical Monodromy, M. P. Nerem, D. Salmon, Seth Aubin, John B. Delos
Experimental Observation Of Classical Dynamical Monodromy, M. P. Nerem, D. Salmon, Seth Aubin, John B. Delos
Arts & Sciences Articles
A Hamiltonian system is said to have nontrivial monodromy if its fundamental action-angle loops do not return to their initial topological state at the end of a closed circuit in angular momentum-energy space. This process has been predicted to have consequences which can be seen in dynamical systems, called dynamical monodromy. Using an apparatus consisting of a spherical pendulum subject to magnetic potentials and torques, we observe nontrivial monodromy by the associated topological change in the evolution of a loop of trajectories.
Experimental Observation Of Classical Dynamical Monodromy, M. P. Nerem, D. Salmon, S. Aubin, John B. Delos
Experimental Observation Of Classical Dynamical Monodromy, M. P. Nerem, D. Salmon, S. Aubin, John B. Delos
Arts & Sciences Articles
A Hamiltonian system is said to have nontrivial monodromy if its fundamental action-angle loops do not return to their initial topological state at the end of a closed circuit in angular momentum-energy space. This process has been predicted to have consequences which can be seen in dynamical systems, called dynamical monodromy. Using an apparatus consisting of a spherical pendulum subject to magnetic potentials and torques, we observe nontrivial monodromy by the associated topological change in the evolution of a loop of trajectories.
Isoscalar Pi Pi, K(K)Over-Bar, Eta Eta Scattering And The Sigma, F(0),F(2) Mesons From Qcd, Raul A. Briceno, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Isoscalar Pi Pi, K(K)Over-Bar, Eta Eta Scattering And The Sigma, F(0),F(2) Mesons From Qcd, Raul A. Briceno, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Arts & Sciences Articles
We present the first lattice QCD study of coupled isoscalar pi pi, K (K) over bar, eta eta S- and D-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the light quark mass corresponding to m(pi) similar to 391 MeV. In the J(P) = 0(+) sector we find analogues of the experimental sigma and f(0)(980) states, where the sigma appears as a stable bound-state below pi pi threshold, and, similar to what is seen in experiment, the f(0)(980) manifests itself as a dip in the pi pi cross section in the vicinity of the …
Highly Repeatable Nanoscale Phase Coexistence In Vanadium Dioxide Films, T. J. Huffman, D. J. Lahneman, (...), M. M. Qazilbash
Highly Repeatable Nanoscale Phase Coexistence In Vanadium Dioxide Films, T. J. Huffman, D. J. Lahneman, (...), M. M. Qazilbash
Arts & Sciences Articles
It is generally believed that in first-order phase transitions in materials with imperfections, the formation of phase domains must be affected to some extent by stochastic (probabilistic) processes. The stochasticity would lead to unreliable performance in nanoscale devices that have the potential to exploit the transformation of physical properties in a phase transition. Here we show that stochasticity at nanometer length scales is completely suppressed in the thermally driven metal-insulator transition (MIT) in sputtered vanadium dioxide (VO2) films. The nucleation and growth of domain patterns of metallic and insulating phases occur in a strikingly reproducible way. The completely deterministic nature …
Detecting A Heavy Neutrino Electric Dipole Moment At The Lhc, Marc Sher, Justin R. Stevens
Detecting A Heavy Neutrino Electric Dipole Moment At The Lhc, Marc Sher, Justin R. Stevens
Arts & Sciences Articles
The milliQan Collaboration has proposed to search for millicharged particles by looking for very weakly ionizing tracks in a detector installed in a cavern near the CMS experiment at the LHC. We note that another form of exotica can also yield weakly ionizing tracks. If a heavy neutrino has an electric dipole moment (EDM), then the milliQan experiment may be sensitive to it as well. In particular, writing the general dimension-5 operator for an EDM with a scale of a TeV and a one-loop factor, one finds a potential EDM as high as a few times 10(-17) e-cm, and models …