Colloquia & Seminars
  • JQI PostDoc Seminars
    Speakers, Titles and Abstracts to follow
    When: Mon, December 1, 2014 - 11:00am
    Where: CSS 2400
  • EPT Seminar
    Title: Leptophilic New Physics: Dark Matter and the Muon g-2

    Speaker: Susanne Westhoff, University of Pittsburgh

    Abstract: New heavy particles that couple only to leptons may explain the observed discrepancy in the muon anomalous magnetic moment, g-2. I discuss how the LHC can probe such new particles in direct production. Leptophilic particles are also promising candidates of dark matter, since they evade constraints from scattering off nuclei. I show that LEP constraints from loop-induced four-lepton interactions are comparable or superior to mono-photon searches. At a future electron-positron collider, lepton interactions can reveal details about the scale and structure of dark sectors.
    When: Mon, December 1, 2014 - 3:00pm
    Where: PSC 3150
  • Space and Cosmic Ray Physics
    Speaker Name: Mei-Ching Fok

    Speaker Institution : The Comprehensive Inner Magnetosphere-Ionosphere Model

    Title : The Comprehensive Inner Magnetosphere-Ionosphere Model

    Abstract : Simulation studies of the Earth’s radiation belts and ring current are very useful in understanding the acceleration, transport, and loss of energetic particles. Recently, the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model were merged to form a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. CIMI solves for many essential quantities in the inner magnetosphere, including ion and electron distributions in the ring current and radiation belts, plasmaspheric density, Region 2 currents, convection potential, and precipitation in the ionosphere. It incorporates whistler mode chorus and hiss wave diffusion of energetic electrons in energy, pitch angle, and cross terms. CIMI thus represents a comprehensive model that considers the effects of the ring current and plasmasphere on the radiation belts. We have performed a CIMI simulation for the storm on 5–9 April 2010 and then compared our results with data from the Two Wide-angle Imaging Neutral-atom Spectrometers and Akebono satellites. We identify the dominant energization and loss processes for the ring current and radiation belts. We find that the interactions with the whistler mode chorus waves are the main cause of the flux increase of MeV electrons during the recovery phase of this particular storm. When a self-consistent electric field from the CRCM is used, the enhancement of MeV electrons is higher than when an empirical convection model is applied. We also demonstrate how CIMI can be a powerful tool for analyzing and interpreting data from the new Van Allen Probes mission.

    Notes: Coffee, Tea & Cookies 4:15-4:30 PM

    When: Mon, December 1, 2014 - 4:30pm
    Where: Computer & Space Science Building, Room 2400
  • EPT Joint Seminar w/ Johns Hopkins
    Joint Particle theory-experiment Maryland-Hopkins Seminar

    Seminar will be preceded by lunch at 12:30 pm. The talk is from 2:00 to 3:00 pm.

    Title: Prospects for the direct detection of dark matter

    Speaker: Carter Hall, University of Maryland

    Abstract: The basic nature and composition of the dark matter remains one of the most important outstanding issues in fundamental physics. One promising approach to address this question is to search for the interaction of our own galaxy's dark matter halo locally in a terrestrial laboratory. Over the last 30 years two classes of experiments have carried out this program: microwave cavity axion searches, and WIMP nuclear recoil searches. Both of these techniques have already made much progress, and the next 10 to 15 years are expected to be particularly interesting as the instrumental sensitivity grows. In fact, the experiments being planned now are expected to cover almost all of the parameter space that nature has provided for such searches. This talk will review the current status of the experiments and discuss the likely path of this field in the next several years.
    When: Tue, December 2, 2014 - 12:30pm
    Where: PSC 3150, University of Maryland
  • Informal Statistical Physics Seminar
    Speaker Name: Professor Marina Guenza

    Speaker Institution : University of Oregon

    Title: Thermodynamic Consistency and Other Challenges in Coarse-Graining Models.
    When: Tue, December 2, 2014 - 1:15pm
    Where: Room 1116, IPST Building, Bldg. 85
  • Physics Colloquium
    Speaker Name: Dennis Papadopoulos

    Speaker Institution: University of Maryland

    Title: Space as an open plasma laboratory

    Abstract: By the late 19th century engineers and experimental scientists knew the behavior of radio waves and understood how and at what frequencies they could transmit information over large distances. However the puzzling question was why the signals followed the curvature of the earth. It took more than 20 years to discover the “ionosphere” an “electrically active” region starting 100km above the earth that reflected the radio waves similar to a mirror returning to the ground. The importance of controlling the long-range propagation of radio waves for military and commercial purposes necessitated the understanding of the properties of the new medium, the ionosphere, and initiated a novel method of experimentation radio sounding: sending radio waves to the ionosphere and detecting the properties of the return signal (travel time, amplitude, direction and polarization). Radio sounding transformed atmospheric studies from passive observations to active “cause and effect” studies similar to laboratory experiments. It revealed that the ionosphere is a very unusual magnetized plasma medium with relatively low electron concentration and low dissipation, extending from 100 to 300 km above the ground. While initially radio sounding was performed with low power radio transmitters recently developed phased array transmitters with Effective Radiative Power (ERP) larger than 1 GW allowed frontier research in nonlinear plasma physics, geophysics and radio science with implications to space weather, Van Allen belts, GPS signals and magnetospheric probing. Following a historical introduction to the subject the presentation will focus on recent physics achievements, including:
    • Creation of artificial ionization layers.
    • Langmuir waves, parametric instabilities, electron acceleration and artificial aurora.
    • Virtual antennas at ELF/VLF frequencies and their use in magnetospheric, ionospheric and underground probing.
    • Artificial mirrors for frequencies in the GHz range.

    When: Tue, December 2, 2014 - 4:00pm
    Where: PSC Lobby
  • Nuclear Physics Seminar
    Title: Magnetized relativistic plasma as a Weyl metal

    Speaker: Igor Shovkovy, ASU

    Abstract: Unusual chiral properties of the ground state of dense relativistic matter in a strong magnetic field will be discussed. The main emphasis will be placed on the dynamical generation of the chiral shift in relativistic matter. From the physics viewpoint, the chiral shift determines a relative shift of the longitudinal momenta (along the direction of the magnetic field) in the dispersion relations of opposite chirality fermions. In solid state physics, it was proposed that Weyl metals with such hypothetical property could exist when the time-reversal symmetry is broken, but not necessarily by a constant external magnetic field. I will argue that the magnetic field causes ordinary relativistic matter to become a Weyl metal. (This should also work for recently discovered Dirac metals.) The corresponding ground state is characterized by a chiral asymmetry at the Fermi surface that affects low-energy physics. Chiral asymmetry could be relevant for compact stars and, perhaps, also other systems.
    When: Wed, December 3, 2014 - 1:00pm
    Where: PSC 3150
  • Applied Dynamics Seminar
    Speaker Name: Seth Putterman

    Speaker Institution : UCLA

    Title: Translating sonoluminescence to therapy for MRSA chronic wounds

    When: Thu, December 4, 2014 - 12:30pm
    Where: IREAP Large Conference Room, ERF 1207
  • CNAM Condensed Matter Colloquium Refreshments

    When: Thu, December 4, 2014 - 1:30pm
    Where: Rm 1305F, the "new" Toll Room
  • CNAM Condensed Matter Colloquium
    Speaker: Victor Yakovenko, University of Maryland

    Title: Tilted loop currents in cuprate superconductors

    Abstract: The paper briefly surveys theoretical models for the polar Kerr effect (PKE) and time-reversal symmetry breaking in the pseudogap phase of cuprate superconductors. By elimination, the most promising candidate is the tilted loop-current model, obtained from the Simon-Varma model by tilting one triangular loop up and another one down toward the apical oxygens. The model is consistent with the PKE, spin-polarized neutron scattering, and optical anisotropy measurements. Spontaneous currents in this model flow between the in-plane and apical oxygens in such a manner that each oxygen belongs to one current loop. This loop-current pattern is similar to the spin order in the magnetoelectric antiferromagnet Cr2O3, where the PKE is observed experimentally. By analogy, it should be possible to train the PKE sign in the cuprates magnetoelectrically. Several experiments are proposed to confirm the loop-current order: the magnetic-field-induced polarity, the nonlinear anomalous Hall effect, and the second-harmonic generation. A similar order parameter was recently revealed in Sr2IrO4 by nonlinear optical harmonic generation. Reference:
    When: Thu, December 4, 2014 - 2:00pm
    Where: Rm 1201, Toll Bldg
  • Gravity Theory Seminar
    Title: Strong Cosmic Censorship

    Speaker: Jim Isenberg, University of Oregon

    Abstract: The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his "Strong Cosmic Censorship Conjecture") that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that “BKL behavior” (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying Strong Cosmic Censorship in that family. We discuss what is known about BKL behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss new results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship.
    When: Fri, December 5, 2014 - 2:00pm
    Where: PSC 3150
  • JQI Seminar
    Speaker Name: Andrew Houck

    Speaker Institution: Princeton

    Title and Abstract to follow

    Host: James Williams
    Title and Abstract to follow
    When: Mon, December 8, 2014 - 11:00am
    Where: CSS 2400
  • EPT Seminar
    Title: tk

    Speaker: Arun Thalapillil, Rutgers

    Abstract: tk
    When: Mon, December 8, 2014 - 3:00pm
    Where: PSC 3150
  • Space and Cosmic Ray Physics Seminar
    Speaker Name: Joel Dahlin

    Speaker Institution : University of Maryland

    Title: TBA

    Abstract: TBA

    Notes: Coffee, Tea & Cookies 4:15-4:30 PM

    When: Mon, December 8, 2014 - 4:30pm
    Where: Computer & Space Science Building, Room 2400
  • CMTC Seminar
    Speaker Name: Subir Sachdev

    Speaker Institution: Harvard

    Title: Order and criticality in the cuprate superconductors

    Abstract: A central mystery posed by the Cu-based high temperature superconductors has been the nature of their electronic state at low hole density. I will survey the remarkable progress made by recent experiments towards solving this mystery, with the first discovery of a density wave with a d-form factor. Aspects of this discovery were anticipated by theory. I will also discuss implications of these advances for the higher temperature “pseudogap” state, and for a quantum-critical point at optimal doping.

    Host: Sankar Das Sarma
    When: Tue, December 9, 2014 - 11:00am
    Where: 2205 Toll Physics Building
  • Physics Colloquium
    Speaker Name: Subir Sachdev

    Speaker Institution: Harvard

    Title: Quantum matter without quasiparticles

    Abstract: The quasiparticle concept is the foundation of our understanding of the dynamics of quantum many-body systems. It originated in the theory of metals, which have electron-like quasiparticles; but it is also useful in more exotic states like those found in fractional quantum Hall systems. However, modern materials abound in systems to which the quasiparticle picture does not apply, and developing their theoretical description remains one of the most important challenges in condensed matter physics. I will describe recent progress in understanding the dynamics of two systems without quasiparticles: the superfluid-insulator transition of ultracold atoms, and the `strange metal’ found in the high temperature superconductors. Some of this progress relies on holographic methods which map non-quasiparticle quantum systems to the dynamics of black hole horizons.

    When: Tue, December 9, 2014 - 4:00pm
    Where: PSC Lobby
  • Nuclear Physics Seminar
    Title: T-reflections and vacuum energie

    Speaker: David McGady, Princeton

    Abstract: tk
    When: Wed, December 10, 2014 - 1:00pm
    Where: PSC 3150
  • Applied Dynamics Seminar
    Speaker Name: Brian Hunt

    Speaker Institution: UMD

    Title: Defining Chaos

    When: Thu, December 11, 2014 - 12:30pm
    Where: IREAP Large Conference Room, ERF 1207
  • Refreshments for CNAM Cond. Matter Colloquium

    When: Thu, December 11, 2014 - 1:30pm
    Where: Room 1305F, the "new" Toll Room
  • CNAM Colloquium
    SPEAKER: Nadya Mason, University of Illinois

    When: Thu, December 11, 2014 - 2:00pm
    Where: Room 1201

Department of Physics

University of Maryland
College Park, MD 20742-4111
Phone: 301.405.3401
Fax: 301.314.9525