Past Events

Astro Seminar: "Fundamental Physics from the Nonlinear Universe"
October 18, 2017  2:00 pm
David Rittenhouse Laboratory, A4
Marcel Schmittfull (IAS)
The cosmology community is running a large program of galaxy surveys over the next 10 years. Our goal is to map out the properties of dark energy as a function of time, measure the sum of neutrino masses, and study the origin of the Universe with unprecedented precision. A key limitation for these efforts is how to extract cosmological information from small scales that are affected by nonlinear dynamics.

High Energy Theory Seminar: "A Toy Model of Axion Gauge Field Inflation"
October 16, 2017  2:00 pm
David Rittenhouse Laboratory, 2N36
Robert Caldwell (Dartmouth College)
We present a toy model of an axion gauge field inflation scenario that yields viable density and gravitational wave spectra. The scenario consists of an axionic inflaton in a steep potential that is effectively flattened by a coupling to a collection of nonAbelian gauge fields. The model predicts a bluetilted gravitational wave spectrum that is dominated by one circular polarization, resulting in unique observational targets for cosmic microwave background (CMB) and gravitational wave experiments.

*Special Condensed Matter Seminar*: "Selforganization and Selfassembly in Biomolecular Systems"
October 13, 2017  2:00 pm
David Rittenhouse Laboratory, A2
Prof. Erwin Frey (University of Munich)
Active matter is a fascinating new field in soft matter physics aiming to understand how interacting active particles selforganize into an intriguing set of patterns and collective nonequilibrium states. Superficially, flocks of animals, selfpropelled microorganisms or cytoskeletal systems appear to display similar phenomenologies, hinting towards universal organizing principles.

HET & HEE Joint Seminar: "Digging Deeper for New Physics in the LHC Data"
October 10, 2017  1:30 pm
Center for Particle Cosmology
David Shih (Rutgers University)

PHYSICS & ASTRONOMY CAREER SEMINAR: 10 Essential Steps to Successful Job Hunting for Physics PhD Students
October 5, 2017  12:00 pm
David Rittenhouse Laboratory, 3W2
Dr. Joseph Barber, Senior Associate Director (Penn Career Services)
Whether you are applying for faculty positions or for jobs in the broad range of other industries/fields that value a STEM PhD, there is plenty you can and should be doing throughout your PhD to position yourself for success. Attend this session to get advice about what to do in your limited professional and career development time to understand yourself and your career goals, explore your career options, and to develop an effective job searching strategy.

Condensed Matter Seminar: "The Case for an Exciton Metal in Bilayer Graphene"
October 4, 2017  4:00 pm  5:00 pm
David Rittenhouse Laboratory, A4
Michael Zaletel (Princeton University)
Graphene based heterostructures have emerged as a pristine platform for exploring the interplay of symmetry, topology and nonAbelian excitations in the quantum Hall regime. I will begin with a theoretical review of the quantum Hall effect in bilayer graphene before discussing results in collaboration with the Young Lab at UCSB. Using insitu control of the density and electromagnetic fields, they find a rich phase diagram which features a plateau at halffilling of a Landau level with a gap several times larger than previously observed.

High Energy Theory Seminar: (TBA)
October 2, 2017  2:00 pm
David Rittenhouse Laboratory, 2N36
Mukund Rangamani (UC Davis)

Joint Mathematics & Physics Seminar: 6D SCFTs and Group Theory
September 28, 2017  4:30 pm
David Rittenhouse Laboratory, 4C2
Tom Rudelius (IAS)
Certain classes of superconformal field theories in six dimensions (6D SCFTs) are in onetoone correspondence with certain classes of group homomorphisms. In this talk, we will see that this correspondence allows us to classify homomorphisms that were previously unknown in the mathematics literature and understand aspects of 6D SCFTs that were previously unknown in the physics literature. We speculate on the implications for the future study of 6D SCFTs and these group homomorphisms.

Condensed Matter Seminar: "Jamming of noncircular and deformable particles"
September 27, 2017  4:00 pm  5:00 pm
David Rittenhouse Laboratory, A4
Mark Shattuck (City University of New York)
We study mechanically stable packings of deformable and rigid 2D circulopolygons using computer simulations. A 2D circulopolygon is a particle shape formed by the collection of all points equidistant from the edge of a polygon. It is a generalization of the 2D circulocylinder and a circle, which are the collections of all points equidistance from a line and a point, respectively. In our model, the circulopolygon can be deformable, where the only constraint on the particle is that shape factor, the ratio of the area of the polygon to the square of the perimeter, is fixed.

Astro Seminar: "Cosmology with Galaxy Clusters: from Weighing the Giants to LSST"
September 27, 2017  2:00 pm
Anja von der Linden (Stony Brook)
Surveys of galaxy clusters provide a sensitive probe of cosmology by measuring the evolution of the halo mass function. However, already current cluster surveys are systematically limited by uncertainties in the relation between cluster mass and observables (e.g. Xray luminosity, cluster richness, SZ decrement). Cluster weak lensing is the most promising observational method to calibrate the mass scaling to the needed precision but requires the control of systematic errors to a few percent each.