Apr 26, 2017 · 1:30 p.m.– 2:30 p.m. · PCTS Seminar Room
Elemental semi metals, Bi, As, Sb, alpha-Sn and Graphehe which straddle an insulator and a metal are fascinating.
Bismuth, a member in this group has been investigated for more than a century, resulting in discovery of some well known effects in solid state physics. New phenomena have appeared in recent times.
One such surprise is discovery of superconductivity at 0.5 mK.
Focussing on a quasi one dimensional organization of half filled bands in this system, I will present a rich hidden physics including a crashed high Tc superconductivity and a normal state containing superconducting phase fluctuations.
Apr 27, 2017 · 4:00 p.m.– 5:00 p.m. · Jadwin A10
In 2015 the Large Hadron Collider (LHC) resumed proton collisions at a new record energy of 13 trillion electronvolts (13 TeV) and doubled the interaction rate achieved in the 2010-2012 run. With the discovery of the Higgs boson in Run 1, the search for new particles and interactions beyond those described by the standard model has intensified in Run 2, during which the amount of data collected has already eclipsed the previous datasets at 7 and 8 TeV. I will describe the challenges presented by the new running conditions, how those challenges were met by the CMS experiment, and selected results from the 13 TeV data. Near-term and long-term goals will also be discussed, including detector upgrades targeting the High-Luminosity LHC era set to begin in the middle of the next decade.
Apr 28, 2017 · 12:00 p.m.– 1:00 p.m. · Joseph Henry Room
Insights into Supermassive Black Hole Mergers, Stalling and Demographics with Pulsar Timing Arrays
Galaxy mergers are a standard aspect of galaxy formation and evolution, and likely all large galaxies contain central supermassive black holes (SMBH). Here I discuss a new bottom-up approach to identifying continuous nanohertz gravitational wave (GW) host galaxies by using massive elliptical galaxies in the 2 Micron All Sky Survey, assessing the likelihood of detecting one of these sources with Pulsar Timing Arrays (PTAs), their contribution to the GW background and its anisotropy, and report on the characteristics of the most detected SMBH binaries and host galaxies. We find that out to 225 Mpc there are on average 91 sources emitting GWs in the PTA band and 7 stalled binaries. The chance of detecting these GW sources with current PTA data is <1%, however in the next 10 years PTAs probe a region of the parameter space rich in sources, making a 3-sigma (or better) detection likely, depending on the source position of the sky and the ability to subtract the GW background.
HET Seminar | Wolfger Peelaers, Rutgers University | "4d/2d correspondences, localization and surface operators"
Apr 28, 2017 · 1:45 p.m.– 2:45 p.m. · PCTS Seminar Room
Four-dimensional N=2 supersymmetric and superconformal quantum field theories take part in various 4d/2d correspondences, which map computations of certain protected data of the four-dimensional theory to problems in two-dimensional models. In this talk, I will explore the role of surface operators in two such correspondences, namely the AGT correspondence and the relation to chiral algebras. In the former, I will argue that a configuration of intersecting “M2-brane surface operators” in the four-dimensional theory translates in the insertion of a generic degenerate vertex operator, labeled by two arbitrary representations, in the Liouville/Toda correlator. In the correspondence with chiral algebras, considering the concrete example of free hypermultiplets, I will leverage a novel localization computation to identify the insertion of a class of surface operators orthogonal to the chiral algebra plane with the insertion of specific vertex operators in the chiral algebra.
May 2, 2017 · 4:00 p.m.– 5:30 p.m. · Jadwin 303
Donald R. Hamilton Lecture - Charles Kane, University of Pennsylvania; "Topological Phases of Matter"
May 4, 2017 · 8:00 p.m.– 9:30 p.m. · McDonnell A02
Matter can arrange itself in the most ingenious ways. In addition to the solid, liquid and gas phases that are familiar in classical physics, quantum mechanics enables the existence of electronic phases of matter that can have both exotic and useful properties. In the last century, the thorough understanding of the simplest quantum electronic phase - the electrical insulator - enabled the development of the solid state electronics technology that is ubiquitous in today's information age. In the present century, new "topological" electronic phases are being discovered that may enable future technologies by allowing the seemingly impossible to occur: indivisible objects, like an electron or a quantum bit of information, can be split into two, allowing mysterious features of quantum mechanics to be harnessed. Our understanding of topological phases, which was celebrated by the 2016 Nobel Prize in physics, builds on deep ideas in mathematics. We will try to convey that they are as beautiful as they are fundamental.
May 15, 2017 · 1:15 p.m.– 2:30 p.m. · PCTS Seminar Room