Past Events

  • High Energy Seminar: "T-Duality and Scattering of Stringy States"

    David Rittenhouse Laboratory, 2N36

    Jnan Maharana (IOP Bhubaneswar)

    I shall review some of the salient features of T-duality from the
    perspective of the worldsheet description of a closed compactified bosonic
    string. The vertex operators associated with the moduli G and B (arising
    from the compatification of graviton and antisymmetric tensor in higher
    dimensions) will be constructed. The KLT formalism will be utilized to
    show the T-duality transformation properties of vertex operators.

  • Condensed Matter seminar: "Tracking Photoinitiated Dynamics of Photosystem I and Model Systems Through Ultrafast Spectroscopy"

    David Rittenhouse Laboratory, A4

    Jessica Anna, University of Pennsylvania

    Photosystem I (PSI) is a natural light harvesting complex that catalyzes oxygenic photosynthesis through a trans-membrane electron transfer. It is also known to be one of nature’s most efficient energy converters – having a quantum efficiency of 100%. The high quantum efficiency of PSI has led to many studies focusing on understanding the mechanism of electronic energy transfer and charge separation in this system.

  • Astro Seminar: "The Remarkable Proto-planetary Disks HL Tau: Watching the Formation of Planets"

    David Rittenhouse Laboratory, A4

    Crystal Brogan (NRAO)

    Spatially resolved ALMA studies of protoplanetary disks at millimeter wavelengths are revolutionizing the study of these precursors to solar systems. In this talk I will present results from observations of the protoplanetary disk HL Tau with 3.5 AU resolution. I will also review the diverse range of modeling work that has emerged to explain the remarkable dust ring structure of HL Tau. Finally, I will show tantalizing new observational results that suggest such structures may be ubiquitous.

  • Experimental Particle Physics: "Di-Higgs at the LHC: Current Status and Future Prospects"

    David Rittenhouse Laboratory, 4C8

    John Alison (University of Chicago)

    I will discuss motivations for searching for di-Higgs production at the LHC. Recent results and projected sensitivities will be presented with particular emphasis on the dominant hh->4b channel.

  • Math-Bio seminar: "Vector diffusion maps and the graph connection Laplacian"

    Carolyn Lynch Laboratory, 318

    Amit Singer, Princeton University

    Vector diffusion maps (VDM) is a mathematical framework for organizing and analyzing high-dimensional datasets that generalizes diffusion maps and other nonlinear dimensionality reduction methods, such as LLE, ISOMAP, and Laplacian eigenmaps. Whereas weighted undirected graphs are commonly used to describe networks and relationships between data objects, in VDM each edge is endowed with an orthogonal transformation encoding the relationship between the data at its vertices. The graph structure and orthogonal transformations are summarized by the graph connection Laplacian.

  • High Energy Theory: Relative Entropy of Excited States in Conformal Field Theories

    David RittenhouseLaboratory, 2N36

    Gabor Sarosi (VUB)

    We study the relative entropy between the reduced density matrices obtained from globally excited states in conformal field theories of arbitrary dimensions. We find a general formula in the small subsystem size limit.  When one of the states is the vacuum of the CFT, our result matches with the holographic entanglement entropy computations in the corresponding bulk geometries, including AdS black branes. We also discuss the first asymmetric part of the relative entropy and comment on some implications of the results on the distinguishability of black hole microstates in AdS/CFT.

  • Topology Workshop

    David Rittenhouse Laboratory, A4

    Professors Randall Kamien, Robert MacPherson, and Konstantin Mischaikow

    For more information or to register, please go here: https://goo.gl/5TKikP

  • Experimental Particle Physics: "Improving T2K Oscillation Results with a Maximum Likelihood Event Reconstruction"

    David Rittenhouse Laboratory, A6

    Andrew Missert (University of Colorado, Boulder)

    The Tokai-to-Kamioka (T2K) experiment is an accelerator-based long-baseline neutrino oscillation experiment that uses a unique off-axis neutrino beam to precisely measure the parameters that govern neutrino flavor oscillations. This talk will outline the experiment and the current results, which offer tantalizing hints regarding the existence of CP violation in the neutrino sector.

  • Condensed Matter seminar: "Life as an emergent phenomenon: how local interactions lead to biological function at the global scale"

    David Rittenhouse Laboratory, A4

    Timon Idema, Delft University of Technology

    Life exists by virtue of collective phenomena. From the cells in a tissue down to the proteins inside a cell, cooperation is key for function and thus survival. We study the physics of these many-component systems, looking for the emergent behaviour that underlies many biological processes. Moreover, we do so while taking the direct environment of our objects of interest into account.

  • Astro Seminar: "Living la vida loca: How to Assemble a Massive Dead Galaxy by z=1.0-1.5"

    David Rittenhouse Laboratory, A4

    Helena Dominguez-Sanchez (Universidad Complutense de Madrid)

    Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation. How were the lives of these galaxies so they died so fast? In this talk, I present recent results on the Star Formation Histories (SFHs) of a sample of ~ 100 quiescent massive (log M > 10 M☉) galaxies at z=1.0 - 1.5.