Events

  • High Energy Theory Seminar: "Some New Mechanisms for Baryogenesis"

    David Rittenhouse Laboratory, 2N36

    Jeremy Sakstein (U of Penn)

    There is more matter than antimatter in the universe, and the origin of this asymmetry is still a mystery. The asymmetry can be generated dynamically in the early universe in a process referred to as baryogenesis but the standard model is not able to produce the amount observed. This is one hint that there is physics beyond the standard model. In this talk, I will present two new baryogenesis mechanisms, one using scalar-tensor theories and the other using Lorentz violating theories.

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  • Astro Seminar: "Moving Mesh Astrophysics"

    David Rittenhouse Laboratory, A4

    Paul Duffel (UC Berkeley)

    Novel methods in recent years have been developed for numerically solving the hydrodynamical and MHD equations relevant to all kinds of astrophysical flows.  I will first (briefly) present one such computational technique, where the numerical grid follows the MHD flow using a "moving mesh".  I will then present some astrophysical scenarios for which I have applied this method, including planet formation and high-energy transients such as supernovae and gamma ray bursts.

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  • Condensed Matter Seminar: "Structure and Topology of Band Structures in the 1651 Magnetic Space Groups"

    David Rittenhouse Laboratory, A4

    Ashvin Vishwanath (Harvard University)

    We describe a powerful theoretical approach to studying electronic band structures, which associates them with elements of a vector space. The set of consistent band structures in a space group can then be expanded in terms of a small set of basis vectors. We calculate the dimension of this vector space, and the necessary electron fillings to obtain band insulators in all magnetic space groups.

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  • Astro Seminar: "Cosmic Microwave Backlight: Illuminating Large-Scale Structure with the Universe's Oldest Photons"

    David Rittenhouse Laboratory, A2

    Colin Hill (IAS/Flatiron Institute)

    Studies of the cosmic microwave background (CMB) radiation have driven the current era of precision cosmology.  The tightest cosmological constraints to date have been derived from the primary CMB anisotropies, which predominantly probe the universe in its infancy.  However, CMB experiments have recently entered a new regime in which constraints derived from the secondary anisotropies -- sourced by effects between our vantage point and the surface of last scattering -- substantially improve upon those derived from the primary anisotropies alone.

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  • High Energy Theory Seminar: (TBA)

    David Rittenhouse Laboratory, 2N36

    Netta Engelhardt (Princeton)

  • HET & HEE Joint Seminar: (TBA)

    David Rittenhouse Laboratory, 4N12

    Cliff Cheung (Caltech)

  • Astro Seminar: "The Chaotic Life Cycles of Planetary Systems"

    David Rittenhouse Laboratory, A4

    Daniel Tamayo (University of Toronto)

    The past two decades have seen the discovery of thousands of new planetary systems in our galactic neighborhood, many of which look drastically different from our own. However, despite this remarkable observational achievement, we are still struggling to generate theoretical frameworks capable of explaining their divergent evolutionary paths. In particular, a central challenge is modeling the often chaotic orbital evolution of planetary systems over typical lifetimes of billions of years, which sculpts the distribution of orbital architectures that we observe at the present day.

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  • 32nd Primakoff Lecture: (TBA)

    David Rittenhouse Laboratory, A8

    Tom Lubensky (University of Pennsylvania)

  • Astro Seminar: (TBA)

    David Rittenhouse Laboratory, A4

    Joy Didier (USC)

  • Condensed Matter Seminar: "Geometry and mechanics of feet and fins"

    David Rittenhouse Laboratory, A4

    Mahesh M. Bandi (Okinawa Institute of Science and Technology Graduate University)

    The stiffness of propulsive appendages, such as feet and fins, is important in locomotory function. In this talk, I show that curvature-induced stiffness is the common principle underlying the stiffness of both primate feet and rayed fish fins. We use mathematical models, physical models, and biological experiments to arrive at this conclusion. The principle is evident in a drooping dollar bill that significantly stiffens upon slightly curling it in the transverse direction.

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