Fall 2014 Seminar Series

Organizer: Boris Botvinnik

Seminars are at 4pm on Tuesdays in 472 Willamette and are preceded by cookies at 3:45.

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9/30/2014 Time Flies: Excess Entropy Production in a Time-dependent Universe
Michael Kellman
University of Oregon, Chemistry and Bio-Chemistry

I will review a new entropy for a system-environment "universe," going beyond the von Neumann entanglement entropy. Then I will look at how the microcanonical entropy, defined classically on the energy shell, generalizes to time-dependent quantum states for which the time-energy uncertainty relation holds.
Boris Botvinnik
10/7/2014 The Ferromagnetic Quantum Phase Transition in Metals
Dietrich Belitz
University of Oregon, Physics Department and Institute of Theoretical Science

In pure ferromagnets that allow for the Curie temperature to be tuned (e.g., by means of hydrostatic pressure) to low temperatures, the order of the transition invariably switches from second order to first order before a quantum critical point is reached. A tricritical point separates a line of second-order transitions from a line of first-order transitions, and in a magnetic field tricritical wings of first-order transitions appear that end in a quantum critical end point. This talk will present a theory that explains this remarkably universal phase diagram in terms of fundamental properties of Fermi liquids.
10/14/2014 High-precision Functional Profiling of Microbial Communities and the Human Microbiome
Curtis Huttenhower
Harvard School of Public Health

Among many surprising insights, the genomic revolution has helped us to realize that we're never alone and, in fact, barely human. For most of our lives, we share our bodies with some ten times as many microbes as human cells; these are resident in our gut and on nearly every body surface, and they are responsible for a tremendous diversity of metabolic activity, immunomodulation, and intercellular signaling. High-throughput sequencing has only recently provided a tool that allows exploration of microbial function, microbe-microbe, and host-microbe interactions in these complex and highly diverse ecologies.

Computational methods for interpreting metagenomic sequencing typically rely on the catalog of thousands of available microbial reference genomes. I will describe a series of bioinformatic approaches for interpreting microbial community sequences using these genomic resources, specifically the PhlAn tools for Phylogenetic Analysis. These provide efficient algorithms for taxonomic profiling within communities - identifying which organisms are present - for phylogenetic reconstruction and placement of new genomes, and for functional profiling and metabolic pathway reconstruction. I will further describe an application of these tools for strain tracking in microbial communities, resulting in the ability to uniquely identify individual human hosts using metagenomic codes.
Boris Botvinnik
10/17/2014 Friday Improving the reporting of Higgs coupling measurements
Kyle Cranmer
New York University & ATLAS

I will identify the formal and practical challenges of reporting of Higgs coupling measurements to the broader (theoretical) community. I’ll then outline some of the progress we’ve made in on the technical side of sharing this information and the formal side in terms of decoupling theoretical uncertainty from the reported results. [arXiv:1401.0080]
Spencer Chang
10/21/2014 Theory and Phenomenology of Dynamical Dark Matter
Brooks Thomas
Reed College

Over the years, a number of simple and elegant ideas have been advanced to explain the nature and origin of the mysterious dark matter in our universe. However, over the last decade, a variety of puzzling experimental results and tantalizing potential signals have emerged which are difficult for these simple proposals to explain without modification. These results should prompt us to consider whether there are any additional, well-motivated ways of addressing the dark-matter problem which may have been overlooked because they do not conform to the conventional picture of what a dark matter candidate should "look like."

In this talk, I present such an alternative framework for addressing the dark-matter problem — one which we call Dynamical Dark Matter (DDM). Within the DDM framework, the requirement of dark-matter stability is replaced by a balancing between decay widths and cosmological abundances across a vast ensemble of individual dark-matter components whose collective behavior transcends that normally associated with traditional dark-matter candidates. In this talk, I provide an overview of the the DDM framework and discuss examples of theoretical contexts in which DDM ensembles naturally arise. I also discuss the phenomenological implications of DDM scenarios and, in particular, how DDM ensembles can potentially be distinguished from traditional dark-matter candidates experimentally at the next generation of direct- and indirect-detection experiments and at the LHC.

[Based on 1106.4546, 1107.0721, 1203.1923, 1204.4183, 1208.0336, 1306.2959, ...]
Spencer Chang
10/28/2014 Illuminating New Physics Through Neutron-Antineutron Transitions
Michael Buchoff
University of Washington

Graham Kribs
10/31/2014 Friday Project 8: A New Type of Electron Spectroscopy and a Path to Measuring the Neutrino Mass Scale
Gray Rybka
University of Washington

To date, attempts to measure the neutrino mass scale have only yielded upper bounds. Improving direct beta-decay mass measurements of the neutrino mass scale requires new ideas in electron spectroscopy. The Project 8 collaboration is developing an ultra-precise technique to measure beta decay electron energy using cyclotron emission by the electron. I will show first results from a prototype experiment demonstrating the observation of single electrons through their cyclotron radiation, and discuss the planned R&D path to build a neutrino mass experiment with this technique.
Spencer Chang
11/4/2014 Tuesday Black Holes
Jim Imamura
University of Oregon Department of Physics

Dietrich Belitz
11/7/2014 Friday Characterizing and Interpreting the Galactic Center GeV Excess
Tracy Slayter
Massachusetts Institute of Technology

Spencer Chang
11/11/2014 Tuesday Calculation of quantum correlations with applications to spins and metallic electrons
Roger Haydock
University of Oregon Department of Physics

Quantum correlations determine the properties of extended systems but present many conceptual and computational difficulties.  My approach is to use ideas from the classical moment problem and the spectra of waves in a cavity to calculate the spectrum of the 'ringing' caused by some local disturbance.  I apply this to the states of interacting spins and the cohesive energies of transition metal crystal structures.
Boris Botvinnik
11/14/2014 Friday A new tool to search for hadronic resonances and a new experiment looking for milli-charged particles
Itay Yavin
McMaster University

I will describe a new tool that can be used to better discriminate resonances that decay hadronically into two jets. This tool is effective in looking for hadronic W, Z, and Higgs bosons, as well as resonances in theories beyond the Standard Model. If time permits I will also describe to you a proposal for a new experiment at the LHC to look for milli-charged particles.
Spencer Chang
11/18/2014 Tuesday Supersymmetry in light of data from the Large Hadron Collider
Arjun Menon
University of Oregon Institute of Theoretical Science

In this talk I will give a brief introduction to Low Energy Supersymmetry with an eye towards Higgs physics and flavor. Due to the large Supersymmetry parameter space, I will focus on constraints on two particular scenarios: Natural Supersymmetry and Electroweak Baryogenesis in the Minimal Supersymmetric Standard Model. In the scenario of Natural Supersymmetry a particular hierarchy of electroweakinos and scalar quarks occurs and the present Large Hadron Collider limits on this scenario will be discussed. The Electroweak Baryogenesis scenario also requires a very particular Supersymmetric spectrum and I will discuss the strong collider constraints on this scenario.
Dietrich Belitz
11/25/2014 Tuesday Surface plasmon in a periodic array of nanowires
David Shapiro
Institute of Automation and Electrometry, Novosibirsk, Russia

Recent achievement in research and development on photionics and nanoplasmonics makes this exciting field important. The examples in the presentation demonstrate the photonics to be also very promising for technology. The periodic array of parallel metallic nanowires on the dielectric substrate with laser excitation is a particular problem of interest. The numerical method is suggested and the effective Green function is derived that reduces the infinite grid of wires with the sub-wavelength period to one elementary cell. We compute the near field distribution and observe a sharp dependence of the field enhancement factor on the incidence angle. We interpret the dependence as the surface plasmon excitation, i.e. electronic plasma oscillations in the metal. The effect may be helpful in tunable photonic devices.
Boris Botvinnik
12/5/2014 Friday The Cosmic Neutrino Background
Lloyd Knox
University of California Davis

Spencer Chang
Last modified: Fr Aug 27 17:54:31 PDT 2010
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