Events at Physics
Events During the Week of December 4th through December 11th, 2016
- Atomic Physics Seminar
- High Energy Lasers at the Extreme Light Infrastructure
- Time: 2:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Tyler Green, ELI project at the Czech Republic.
- Abstract: High energy short pulse lasers are useful tools for probing the structure and dynamics of materials and accelerating particles. The European Union is investing in a network of laser centers focused on fundamental research called the Extreme Light Infrastructure (ELI). ELI hopes to allow the investigation of new regimes of laser-matter interaction with multi-petawatt laser pulses and unprecedented repetition rates. In this talk I will present one of the facilities currently under development in Prague, Czech Republic. While an overview of the laser systems under development will be given, the primary focus of the talk will be on current techniques and principles of high energy laser amplification.
- Host: Yavuz
- Chaos & Complex Systems Seminar
- 2016 Polling in Nation and State: A scorecard
- Time: 12:05 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Charles Franklin, Law and Public Policy and Director of the Marquette University Law School Poll
- Abstract: How did the pre-election polls of 2016, at both national and state levels, perform? What did we learn about the dynamics of the campaign and the issues affecting public polling? How accurate were the polls and were some methods better than others?
- Host: Clint Sprott
- Theory Seminar (High Energy/Cosmology)
- Search For Dark Matter In Terms of Dark Bound States
- Time: 3:30 pm
- Place: 5280 Chamberlin
- Speaker: Yue Zhang, Northwestern
- Abstract: Understanding the nature of dark matter is an open question of central importance to particle physics and cosmology. In this talk, I discuss a model where the dark matter is a fermion charged under a dark U(1) gauge symmetry and its interactions are mediated by a massive dark photon. I will summarize the current status in the search for such a dark sector. The main focus of this talk is on the non-perturbative effects in particular dark matter bound states, which could have strong impact on the interpretation of existing experimental results and lead to new channels for the future search.
- Host: Yang Bai
- Department Meeting
- Closed meeting to discuss personnel matters
- Time: 12:15 pm
- Place: 5310 Chamberlin Hall
- Closed meeting to discuss personnel matters—pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law
Closed to all but tenured faculty
- Host: Albrecht Karle
- R. G. Herb Condensed Matter Seminar
- Universal transport at the edge: Disorder, interactions, and topological protection
- Time: 10:00 am
- Place: Chamberlin 5310
- Speaker: Matthew Foster, Rice University
- Abstract: Topological insulators and superconductors provide condensed matter realizations of the holographic principle: a topological property of the bulk translates into an anomalous time-reversal symmetry at the material surface. This symmetry underlies "topological protection" of the edge or surface states. Protection from disorder effects (Anderson localization) is particularly nontrivial, because surfaces are low dimensional. While this was previously understood for noninteracting models of edge and surface states, the more complicated problem of combined disorder and interaction effects had not been addressed until recently. I will discuss two different examples of universal edge or surface transport that arise in the presence of both. First, I will consider the edge states of 2D topological insulators with Rashba spin-orbit coupling (RSOC). With RSOC, disorder induces a backscattering term in the edge theory. We have shown that transport remains perfectly ballistic in a model that incorporates this term and interactions. The solution involves a mapping to spin 1/2 moment that executes perfect adiabatic evolution in a random magnetic field.  Second, I will discuss the surface states of 3D topological superconductors, and explain why we predict universal surface thermal and (if conserved) spin conductivities. The solution combines various nonperturbative and/or exact methods including conformal field theory, the Finkel'stein non-linear sigma model, and numerics. [2,3] I will also show how disorder enhances topological protection for surface states of recently introduced  model spin-3/2 topological superconductors, which may have applications to ultracold atoms or Half-Heusler compounds.
 H.-Y. Xie, H. Li, Y.-Z. Chou, and M. S. Foster, PRL 116, 086603 (2016)
 H.-Y. Xie, Y.-Z. Chou, and M. S. Foster, PRB 91, 024203 (2015)
 M. S. Foster, H.-Y. Xie, and Y.-Z. Chou, PRB 89, 155140 (2014)
 W. Yang, Yi Li, and C. Wu, PRL 117, 075301 (2016)
- Host: Alex Levchenko
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:href="http://cmb.physics.wisc.edu/journal/index.html">http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Amol Upadhye (email@example.com).
- Host: Amol Upadhye
- Astronomy Colloquium
- The Turbulent Origin of Stars
- Time: 3:30 pm
- Place: 4421 Sterling Hall, Coffee and cookies 3:30 pm, Talk at 3:45PM
- Speaker: Phillip Chang, UW Milwaukee
- Abstract: Recent numerical experiments on the star formation rate on small scales find that the star formation rate is much faster than the Kennicutt-Schmidt law which well-characterizes star formation on galactic scales, and also shows that star formation accelerates with time. Motivated by these results, I will discuss a new dynamical theory of star formation in a turbulent medium that seeks to explain these observed numerical results. I will survey the various theories of star formation and their shortcomings. I will then discuss how we extend previous theories of collapse by considering turbulence as a dynamical variable and closing the fluid equations with a new form of the energy equation. The resulting theory explains these previous numerical results and makes a few predictions that have recently been numerically verified as well as some numerical surprises. I will discuss the implications of this theory on observations.
- Plasma Theory Seminar
- Time: 2:15 pm
- Place: 5280 Chamberlin hall
- Speaker: Chad Williams
- Abstract: tbd
- Host: Daniel J. Den Hartog
- Physics Department Colloquium
- Holiday Colloquium
- Time: 4:30 pm
- Place: 2103 Chamberlin Hall
- Host: 3rd year graduate students