### FOR MORE INFORMATION

**Catherine Broderick**

(781) 736-2803

cbroderi@brandeis.edu

## List of Events

Jump to upcoming seminar: March 23

**Location for all seminars: Abelson 229**

### Fall 2015

**Wednesday, October 14, 2015**

R. Loganayagam (IAS Princeton)

Joint IGERT/Condensed Matter Seminar

Host: Kabir Ramola

Joint IGERT/Condensed Matter Seminar

*Second law and the eightfold structure of relativistic fluid dynamics*Host: Kabir Ramola

**Wednesday, October 28, 2015**

Itamar Procaccia, Weizmann Institute

*What determines force chains in granular media?*

Abstract: The determination of the normal and transverse (frictional) inter-particle forces within a granular medium is a long standing, daunting, and yet unresolved problem. We present a new formalism which employs the knowledge of the external forces and the orientations of contacts between particles (of any given sizes), to compute all the inter-particle forces.

Having solved this problem we exemplify the efficacy of the formalism showing that the force chains in such systems are determined by an expansion in the eigenfunctions of a newly defined operator.

Host: Bulbul Chakraborty

**Wednesday, December 9, 2015**

Arunima Ray (Brandeis)

*Concordance classes of knots and satellite operations*

Abstract: A knot is an embedded circle in 3-dimensional space R^3. It is said to be slice if it is the intersection of an embedded 2-dimensional sphere in R^4 with R^3 considered as a subset of R^4. We can use this notion to define an equivalence relation on knots called concordance, under which the set of knots forms a well-behaved mathematical structure called an abelian group. The group of knot concordance classes plays an important role in the study of 4-dimensional manifolds. In this talk, we will give an overview of knot concordance and describe my work in understanding the action of certain 'satellite operations' on the knot concordance group. Finally we will describe how satellite operations might illuminate a fractal structure in the knot concordance group.

### Spring 2016

**Wednesday, January 27, 2016**

Naziru Awal (Brandeis)

*Piecewise Linear Model of the BZ reaction*

**Wednesday, February 10, 2016**

Ruoran Zhang, Northeastern University (Note: Quantitative Biology Lunch also held at this time).

*Contact Chern-Simons Theory and Legendrian Knots*

Abstract: Chern-Simons theory is a 3-dimensional topological quantum field theory developed by Edward Witten. Bar-Natan studied the perturbative Chern-Simons theory and deduced new integral formula for known invariant of knots([1]). In 2005, Chris Beasley and Edward Witten([3]) developed a theory called contact Chern-Simons theory which combines contact geometry with Chern-Simons theory. This theory is especially suitable for the study of Legendrian knots due to certain symmetry of its action functional.n this talk, I will first introduce the motivation of contact Chern-Simons theory and some basic concepts in contact geometry. Additionally, I will explain why Legendrian knots are related to contact Chern-Simons theory. Then, I will introduce new self-linking invariants of Legendrian knots. These invariants arise from the perturbative expansion of the contact Chern-Simons theory, and they are conjectured to agree with known finite-type invariants derived from the usual Chern-Simons gauge theory. I proved this conjecture at first non-trivial order, in which case the self-linking invariant is a linear combination of the Thurston-Bennequin invariant and the rotation number of the knot([2]). In physics, the self-linking invariants describe terms in the Feynman diagram expansion of the Wilson loop expectation value in contact Chern-Simons theory. At the end, I will show a cancellation of certain Feynman diagrams of the expansion of the Wilson loop expectation value. This result is a check of the finiteness of contact Chern-Simons theory. This is a joint work with Chris Beasley and Brendan McLellan.

**Wednesday, February 17, 2016**

No IGERT seminar (due to Midterm Recess & Neuro Faculty Meeting)

**Wednesday, February 24, 2016**

Open.

**Wednesday, March 2, 2016**

Open.

**Wednesday, March 9, 2016**

Open. (Note: Quantitative Biology Lunch also held at this time).

**Wednesday, March 16, 2016**

No IGERT seminar (due to Neuroscience Faculty Meeting). APS Meeting week.

**Wednesday, March 23, 2016**

Melanie Mitchell, Portland State

Time to be announced.

**Wednesday, March 30, 2016**

Open. (Note different location: Hassenfeld, Levine Ross)

**Wednesday, April 6, 2016**

Open.

**Wednesday, April 13, 2016**

Open. (Note: Quantitative Biology Lunch also held at this time).

**Wednesday, April 20, 2015**

No IGERT seminar (due to Neuroscience Faculty Meeting).

**Wednesday, April 27, 2016**

No IGERT seminar (due to Passover and Spring Recess).