1. Colloquium: Glimpsing Color in the World of Black and White

    01:08:04

    from UK College of Arts & Sciences / Added

    24 Plays / / 0 Comments

    Glimpsing color in a world of black and white Protons, neutrons and all the many other strongly interacting subnuclear particles, known as hadrons, are made of quarks and gluons. These fundamental constituents are held together by a color force described by quantum chromodynamics (QCD). A detailed understanding of how the strong coupling regime of QCD, which is responsible for confinement and dynamical chiral symmetry breaking, determines the spectrum and structure of hadrons will be outlined. Such studies, both experimental and theoretical, color in the picture of strong dynamics. What we know now and the glimpses to come from accelerator facilities like that at Jefferson Lab will be described.

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    • Colloquium: Viscosity, Quark Gluon Plasma, and String Theory

      01:08:21

      from UK College of Arts & Sciences / Added

      58 Plays / / 0 Comments

      Viscosity, quark gluon plasma, and string theory Viscosity is a very old concept which was introduced to physics by Navier in the 19th century. However, in strongly coupled systems, viscosity is difficult to compute from first principle. In this talk I will describe some recent surprising developments in string theory which allow one to compute the viscosity for a class of strongly interacting quantum fluids not too dissimilar to the quark gluon plasma. I will describe efforts to measure the viscosity and other physical properties of the quark gluon plasma created in relativistic heavy ion collisions.

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      • Cosmic Linear Accelerators: Extreme Reconnection and other Surprises from the Crab Nebula

        01:11:43

        from UK College of Arts & Sciences / Added

        17 Plays / / 0 Comments

        The unexpected discovery of gamma-ray flares from the Crab Nebula may have surprising implications for plasma astrophysics. Standard particle acceleration mechanisms cannot account for the energies of the flaring photons. Instead, these observations point toward an acceleration process involving rapid destruction of magnetic field through reconnection. I will discuss the extreme particle acceleration process that may lead to the flares, and the likely role of current-driven instabilities in triggering reconnection in the Crab and elsewhere.

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        • From Voids to Clusters: Gas and Galaxy Evolution in the Local Universe

          01:32:01

          from UK College of Arts & Sciences / Added

          38 Plays / / 0 Comments

          Our understanding of the formation and evolution of galaxies and their large scale structure has advanced enormously over the last decade, thanks to an impressive synergy between theoretical and observational efforts. While the growth of the dark matter component seems well understood, the physics of the gas, during its accretion, removal and/or depletion is less well understood. Increasingly large scale optical surveys are tracing out the cosmic web of filaments and voids. Mathematical tools have been developed to describe these structures and to identify galaxies located in specific environments. HI imaging surveys begin to answer the question: how do galaxies get and lose their gas? The best evidence for ongoing gas accretion is found in the lowest density environments, while removal of gas in the highest density environments stops star formation and reddens the galaxies. Speaker: Jacquiline van Gorkom, Columbia University

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          • From Voids to Clusters: Gas and Galaxy Evolution in the Local Universe - 12 Oct. 2012

            01:32:01

            from UK College of Arts & Sciences / Added

            36 Plays / / 0 Comments

            Our understanding of the formation and evolution of galaxies and their large scale structure has advanced enormously over the last decade, thanks to an impressive synergy between theoretical and observational efforts. While the growth of the dark matter component seems well understood, the physics of the gas, during its accretion, removal and/or depletion is less well understood. Increasingly large scale optical surveys are tracing out the cosmic web of filaments and voids. Mathematical tools have been developed to describe these structures and to identify galaxies located in specific environments. HI imaging surveys begin to answer the question: how do galaxies get and lose their gas? The best evidence for ongoing gas accretion is found in the lowest density environments, while removal of gas in the highest density environments stops star formation and reddens the galaxies. Speaker: Jacquiline van Gorkom, Columbia University

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            • Higgs Discovery: Implications for Particle Physics - 2 Nov. 2012

              01:16:16

              from UK College of Arts & Sciences / Added

              55 Plays / / 0 Comments

              The LHC has recently discovered a Higgs-like resonance with a mass of about 125 GeV. It may be the missing element of the so-called Standard Model of particle physics. This model was proposed a few decades ago, and, after the inclusion of neutrino masses, describes in an accurate way all measured observables not involving gravity. We shall discuss what are the possible implications of the Higgs Discovery for particle physics and, in particular, for theoretical and experimental physics High Energy Physics in the coming years.

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              • Many facets of strongly coupled QFT: from QCD to Cosmology By Anatoly Dymarsky

                01:09:01

                from UK College of Arts & Sciences / Added

                14 Plays / / 0 Comments

                Many facets of strongly coupled QFT: from QCD to Cosmology By Anatoly Dymarsky

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                • The Structure and Evolution of Milky Way-Like Galaxies

                  01:08:20

                  from UK College of Arts & Sciences / Added

                  10 Plays / / 0 Comments

                  Matthew Bershady University of Wisconsin A small fraction of the universe's energy-density is comprised of normal matter. A still smaller fraction is bound into stars and gas that we can see and are responsible for life. This talk examines what we know about the baryon content of, and how stars assembled in, galaxies like the Milky Way (MW). Dynamical measurements from integral-field spectroscopy indicate the baryonic mass of spiral disks is small. Radiative-transfer modeling of dusty, edge-on galaxies reveals super-thin stellar disks previously missed. These findings yield a consistent picture of light disks with young luminosity-weighted stellar ages. A new census from the Sloan Digital Sky Survey-IV, now underway, will test how broadly these results apply to the galaxy population as a whole. This advance allows us to better place the MW in context of today's galaxy population, and to leverage the MW's unique archaeological record against observations of distant galaxies. A critical question that can be resolved is whether stellar age and abundance gradients in galaxy disks are the result of a settling process of decreasingly turbulent gas or dynamical heating.

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