Events - Weekly
December 2012 >>
|Sunday, December 2|
|Monday, December 3|
High Energy Theory Seminar - IAS - Scott Thomas, Rutgers, The State University of New Jersey - TBA
Bloomberg Lecture Hall - Institute for Advanced Study · 2:30 p.m.– 3:30 p.m.
|Tuesday, December 4|
Informal High Energy Theory Seminar - IAS - Raphael Bousso, Lawrence Berkeley National Laboratory - “Is There An Alternative To Firewalls?”
Bloomberg Lecture Hall - Institute for Advanced Study · 1:30 p.m.– 2:30 p.m.
Lessons from a high-Tc superfluid: probing local quantities in a strongly interacting Fermi gas - Yoav Sagi JILA
The collective behavior of an ensemble of strongly interacting fermions is central to many physical systems including liquid 3He, high-Tc superconductors, quark-gluon plasma, neutron stars, and ultracold Fermi gases. However, theoretical understanding of strongly interacting fermions is challenging due to the many-body nature of the problem and the fact that there is no obvious small parameter for a perturbative analysis.
Ultracold atomic Fermi gases are ideal to shed light on this issue, as they provide excellent controllability, reproducibility, and unique detection methods. One of the problems, however, which complicates the interpretation of these experiments, is the inherent density inhomogeneity of the gas which arises due to the harmonic confinement. We have developed a technique to overcome this difficulty by selectively probing atoms near the center of a trapped gas while still retaining momentum resolution. For a weakly interacting Fermi gas of 40K atoms, we present measurements of the momentum distribution that reveal for the first time a sharp Fermi surface. We then apply the technique to a strongly interacting Fermi gas at the Feshbach resonance, where we probe the temperature dependence of the homogeneous Tan’s contact. Finally, we combine the technique with momentum resolved photoemission spectroscopy to study the outstanding issue of the nature of the normal state just above the superfluid transition temperature.
Joseph Henry Room · 2:00 p.m.– 3:30 p.m.
|Wednesday, December 5|
|Thursday, December 6|
Physics Colloquium: Eleni Katifori, Max-Planck Institute for Dynamics & Self-Organization - "The Geometry and Topology of Plant Structures"
The plant kingdom is rich with examples of tissues, organs and entire organisms that uniquely showcase elegant mathematical and physical principles. These principles frequently reflect the interplay between functional necessity and developmental constraints. We discuss two examples that showcase how plants utilize intricate topological and geometrical principles to optimize their function: the evolution of reticulate venation in modern leaves (modeled as a planar distribution networks) and the folding of aperturate pollen (modeled as curved shells). We will focus on pollen, and present some recent results concerning the quasi-inextensional deformation of intrinsically curved surfaces with symmetry of rotation.
Jadwin A10 · 4:30 p.m.– 5:30 p.m.
|Friday, December 7|
High Energy Theory Seminar - Liam Fitzpatrick, Stanford University - "AdS Field Theory and Conformal Field Theory"
We discuss how locality in AdS duals to Conformal Field Theories emerge vis-a-vis bulk Effective Field Theory descriptions with a high-scale cut-off, and the emergence of a weakly-coupled Eikonal limit for high-spin CFT operators. First, we provide necessary and sufficient conditions for a CFT to have a description in terms of a local EFT in AdS. This includes a condition that the Mellin amplitudes of the CFT correlators must be well-approximated by functions that are bounded by a polynomial at infinity in Mellin space, or in other words, that the Mellin amplitudes have an effective theory-type expansion. Next, we take an analytic approach to the CFT bootstrap, studying an Eikonal-type limit of d > 2 dimensional CFT 4-pt correlators where the conformal cross ratios satisfy |u| ≪ |v| ≪ 1. We use this limit to derive exact results concerning the CFT spectrum and OPE coefficients for operators with large angular momentum. We interpret the results as a statement about super-horizon locality in AdS for very general CFTs
PCTS Seminar Room · 1:30 p.m.– 2:30 p.m.
|Saturday, December 8|