Events at Physics |
Events During the Week of October 6th through October 13th, 2013
Monday, October 7th, 2013
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:30 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
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 Le Zhang (lzhang263@wisc.edu) - Host: Peter Timbie
- Condensed Matter Theory Group Seminar
- Superconductivity at the onset of spin-density-wave order in a metal
- Time: 4:30 pm
- Place: Chamberin 5310
- Speaker: Yuxuan Wang, Physics Department
- Abstract: We revisit the issue of superconductivity at the quantum-critical point between a 2D paramagnet and a spin-density-wave (SDW) metal with ordering momentum (pi,pi). This problem is highly non-trivial because the system at criticality displays a non-Fermi liquid behavior and because the effective coupling constant &amp;#955; for the pairing is generally of order one, even when the actual interaction is smaller than fermionic bandwidth. Previous study [M. A. Metlitski, S. Sachdev, Phys.Rev.B 82, 075128 (2010)]has found that the leading renormalization of the pairing vertex contains log2, like in color superconductivity. We analyze the full gap equation and argue that summing up log2 term does not lead to a pairing instability. Yet, superconductivity has no threshold, even if &amp;#955; is set to be small: the subleading log terms give rise to BCS-like Tc&amp;#8733;e&amp;#8722;1/&amp;#955;. We argue that the analogy with BCS is not accidental as superconductivity at a QCP is a Fermi liquid phenomenon -- it comes from fermions which retain Fermi liquid behavior at criticality. We compute Tc for the actual &amp;#955; and find consistency with the numerical results.<br>
- Host: Natalia Perkins
Tuesday, October 8th, 2013
- Chaos & Complex Systems Seminar
- The infinitesimal
- Time: 12:05 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Terry Millar, UW Department of Mathematics
- Host: Clint Sprott
Wednesday, October 9th, 2013
- No events scheduled
Thursday, October 10th, 2013
- Astronomy Colloquium
- Constraining the Cosmological Evolution of Galaxies Using Bars
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Kartik Sheth, NRAO
- Abstract: Stellar bars are a key signpost in the evolutionary history of a disk
galaxy. When a disk is sufficiently massive, dynamically cold and
rotationally supported, and sufficient time has elapsed for the
baryonic matter to exchange energy and angular momentum with the dark
matter halo or the outer disk, the formation of a bar is inevitable.
Therefore understanding the evolution of the bar fraction as a
function of the host galaxy properties and as a function of redshift
provides important clues to the evolutionary history of galaxies. I
will present the latest results on local bars from the Spitzer Survey
of Stellar Structure in Galaxies (S4G) and discuss the observations
for the declining bar fraction with redshift from the COSMOS survey.
A plausible reason for the decline in the bar fraction may be that
galaxy disks were too dynamically hot to host bars at higher redshift
which we have investigated using the DEEP2 / AEGIS data. Together
these data are beginning to provide a coherent and consistent picture
for the assembly history of disks on the Hubble sequence. Using ALMA
we are also studying the evolution of the molecular gas content (and
associated star formation) as a function of redshift and in greater
detail with spatially resolved observations of nearby spirals. I will
describe the latest results of our on-going investigations on galaxy
evolution and star formation with ALMA.
Friday, October 11th, 2013
- Theory Seminar (High Energy/Cosmology)
- The Higgs Boson in the Golden Channel
- Time: 2:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Jamie Gainer, University of Florida
- Abstract: The "Golden Channel", in which the Higgs decays to four leptons via intermediate Z bosons, has played an important role in the discovery of the Higgs and in early measurements of its properties. I review the discovery of the Higgs in this channel and describe ongoing efforts to use this channel to measure Higgs couplings to Z bosons.
- Astronomy Colloquium
- Exoplanetary Systems from Kepler
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Daniel Fabrycky, UC Santa Cruz
- Physics Department Colloquium
- Understanding the Higgs Boson
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: Sridhara Dasu, University of Wisconsin Department of Physics
- Abstract: The July 4th 2012 discovery of a Higgs like Boson is a watershed event in the field of particle physics. The discovery of a particle and a field which is unlike anything else encountered at fundamental level requires stringent scrutiny. Rapid progress in understanding that discovery has been made with the more than double the data accumulated last year. More careful measurements await the upgrades to the accelerator and the experiment. The latest results from the complete data set collected and prospects for future will be discussed in this talk.