Author
Thomas D. Cohen
Other affiliations: University of Washington, University of Pennsylvania
Bio: Thomas D. Cohen is an academic researcher from University of Maryland, College Park. The author has contributed to research in topics: Quantum chromodynamics & Baryon. The author has an hindex of 36, co-authored 235 publications receiving 5417 citations. Previous affiliations of Thomas D. Cohen include University of Washington & University of Pennsylvania.
Topics: Quantum chromodynamics, Baryon, Quark, Nucleon, Meson
Papers published on a yearly basis
Papers
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TL;DR: In the course of the work, a perspective on the many research streams which flow into and out of QCD is offered, as well as a vision for future developments.
Abstract: We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.
457 citations
Technische Universität München1, Novosibirsk State University2, GSI Helmholtz Centre for Heavy Ion Research3, University of Kentucky4, Fermilab5, Washington University in St. Louis6, University of Graz7, University of Vienna8, University of Maryland, College Park9, Max Planck Society10, Vienna University of Technology11, Hampton University12, Thomas Jefferson National Accelerator Facility13, University of Bonn14, University of Washington15, Complutense University of Madrid16, University of Mainz17, Moscow Institute of Physics and Technology18, University of Groningen19, University of Paris-Sud20, Indiana University21, University of California, Davis22, Lawrence Livermore National Laboratory23, University of Helsinki24, University of Virginia25, Istituto Nazionale di Fisica Nucleare26, Forschungszentrum Jülich27, University of Bern28, Warsaw University of Technology29, CERN30, Kent State University31, Utrecht University32, National Research Nuclear University MEPhI33, Lawrence Berkeley National Laboratory34, University of Valencia35, University of Granada36, Brookhaven National Laboratory37, Stony Brook University38, University of Naples Federico II39, University of Santiago de Compostela40, Ruhr University Bochum41, Far Eastern Federal University42
TL;DR: In this paper, the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment, are highlighted, highlighting how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as searches for physics beyond the Standard Model.
Abstract: We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.
433 citations
TL;DR: The trace anomaly and the Hellmann-Feynman theorem lead to a prediction of the gluon condensate that is model independent to first order in the nucleon density, and this prediction implies that the quark condensates is reduced considerably at nuclear matter saturation density.
Abstract: Quark and gluon condensates in nuclear matter are studied. These in-medium condensates may be linked to a wide range of nuclear phenomena and are important inputs to QCD sum-rule calculations at finite density. The Hellmann-Feynman theorem yields a prediction of the quark condensate that is model independent to first order in the nucleon density. This linear density dependence, with slope determined by the nucleon \ensuremath{\sigma} term, implies that the quark condensate is reduced considerably at nuclear matter saturation density---it is roughly 25--50 % smaller than the vacuum value. The trace anomaly and the Hellmann-Feynman theorem lead to a prediction of the gluon condensate that is model independent to first order in the nucleon density. At nuclear matter saturation density, the gluon condensate is about 5% smaller than the vacuum value. Contributions to the in-medium quark condensate that are of higher order in the nucleon density are estimated with mean-field quark-matter calculations using the Nambu--Jona-Lasinio and Gell-Mann--L\'evy models. Treatments of nuclear matter based on hadronic degrees of freedom are also considered, and the uncertainties are discussed.
246 citations
TL;DR: The problem of how to understand this phenomenological behavior in terms of functional integrals is solved for the case of an isospin chemical through the study of the spectrum of the operator gamma(0)(/D+m).
Abstract: In a Euclidean space functional integral treatment of the free energy of QCD, a chemical potential enters only through the functional determinant of the Dirac operator which for any flavor is $\mathrm{D\ensuremath{\llap{
ot\;}}}+m\ensuremath{-}{\ensuremath{\mu}}_{f}{\ensuremath{\gamma}}_{0}$ (where ${\ensuremath{\mu}}_{f}$ is the chemical potential for the given flavor). Any nonzero $\ensuremath{\mu}$ alters all of the eigenvalues of the Dirac operator relative to the $\ensuremath{\mu}=0$ value, leading to a naive expectation that the determinant is altered and which thereby alters the free energy. Phenomenologically, this does not occur at $T=0$ for sufficiently small $\ensuremath{\mu}$, in contradiction to this naive expectation. The problem of how to understand this phenomenological behavior in terms of functional integrals is solved for the case of an isospin chemical through the study of the spectrum of the operator ${\ensuremath{\gamma}}_{0}(\mathrm{D\ensuremath{\llap{
ot\;}}}+m)$. The case of the baryon chemical potential is briefly discussed.
174 citations
TL;DR: In this paper, a review of applications of QCD sum-rule methods to the physics of nuclei are reviewed, with an emphasis on calculations of baryon self-energies in infinite nuclear matter.
146 citations
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TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
Journal Article•
28,685 citations
TL;DR: This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
Abstract: Graphene is a wonder material with many superlatives to its name. It is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have zero effective mass, and can travel for micrometers without scattering at room temperature. Graphene can sustain current densities six orders of magnitude higher than that of copper, shows record thermal conductivity and stiffness, is impermeable to gases, and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
12,117 citations
TL;DR: In this article, the chiral magnetic effect of topological charge changing transitions in the quark-gluon plasma has been studied and an electromagnetic current is generated along the magnetic field.
Abstract: Topological charge changing transitions can induce chirality in the quark-gluon plasma by the axial anomaly. We study the equilibrium response of the quark-gluon plasma in such a situation to an external magnetic field. To mimic the effect of the topological charge changing transitions we will introduce a chiral chemical potential. We will show that an electromagnetic current is generated along the magnetic field. This is the chiral magnetic effect. We compute the magnitude of this current as a function of magnetic field, chirality, temperature, and baryon chemical potential.
1,821 citations
TL;DR: A review of the development of random-matrix theory (RMT) during the last fifteen years is given in this paper, with a brief historical survey of the developments of RMT and of localization theory since their inception.
1,750 citations