The CTP Lunch Club meets every Friday at noon in the Cosman seminar room, 6C-442 (provided that there are sufficient speakers). A light lunch will be provided begining at 11:50am (usually pizza, however some other options may be explored).

The seminars are designed for graduate students and should be accessible to all students. First year students are particularly encouraged to attend so that they may learn about research being performed in the CTP. The goal is learning, and to encourage participation, the seminars will be for students only.

Email notification of the club will be sent to the ctp-all, ctp-postdocs and ctp-students email lists as appropriate. If you wish to speak, or have suggestions about speakers and/or possible workshop topics, please contact the organizers, Ethan Dyer at edyer_at_mit[dot]edu, and Mark Mezei at mezei_at_mit[dot]edu.

- September 22

Chris Lee

The Generation of Matter

The Big Bang and Inflation produced a Universe presumably with equal amounts of matter and antimatter. How and when our Universe came to be made dominantly of matter is one of the great mysteries in modern physics.

In this talk I explore the possibility that the excess matter was generated during the electroweak phase transition, the latest possible time when such an excess could have arisen. Such a scenario requires new particles beyond those in the Standard Model, such as those predicted by supersymmetry. I also describe my current research toward a more consistent and rigorous theoretical description based on quantum field theory of the evolution of particle densities in the hot and out-of-equilibrium environment created by the phase transition.

Faculty and postdocs welcome.

- October 1

Shelby Kimmel

- October 8

Brian Swingle

Entanglement, twist fields, and holography

In this talk I will discuss ultra new work about the structure of entanglement in quantum field theory. The main quantity of interest is the quantum mutual information which is a very useful refinement of the entanglement entropy that remains finite in the continuum limit. I will explain what mutual information is, why we care about it, and more generally, why we care about the structure of entanglement in quantum many body systems. I also describe the properties of higher dimensional twist fields, familiar from 1+1 dimensional CFT, which encode the entanglement structure. Finally, I will explain what all this has to do with holography and how holography has been useful in this endeavor. I will make every effort to make the talk accessible to all levels of knowledge.

- October 15

Dave Gossett

Randomness, Phase Transitions and Quantum Adiabatic Algorithms

This talk is about random constraint satisfaction problems and Quantum Adiabatic Algorithms for solving them. I'll describe a recently proposed way in which the quantum adiabatic algorithm can fail due to a first order quantum phase transition, and whether or not this problem can be overcome. I will discuss how the randomness in these problems differs from other "fully random" problems such as random energy models.

- October 22

Abolhassan Vaezi

Confinement/deconfinement problem in 2+1 D Dirac Model

In this talk I discuss the compact U(1) gauge theory of strongly correlated Hubbard model on the honeycomb lattice. It turns out that the low energy theory of excitations can be described by 8 species of Dirac fermions coupled to a U(1) gauge theory. We should also take instantons into consideration because of the compactness of the microscopic lattice gauge theory. I investigate the confinement/deconfinement problem and the fate of the spin liquid phase. It will be shown that the instanton proliferation breaks the translation symmetry spontaneously and we finally obtain a charge/spin gapped phase.

Faculty and Postdocs are welcome.

- November 5

Mohamad Maghrebi

A Multiple-scattering Expansion of the Casimir Energy

The Casimir energy is the vacuum energy of a quantum filed theory with nontrivial boundary conditions. Since the discovery of this effect in 1948, the dependence on shape and geometry of the energy has remained at a primitive stage. A recently developed formalism enables systematic computation of the Casimir forces in terms of a multipole expansion. In this talk, I will give the results of the first analytic study of the Casimir force of edges and tips. I will use a multiple scattering scheme to obtain explicit formula for the interaction of a half-plate (edge) or a cone (tip) with an infinite plate. The multiple scattering series can be organized in a diagrammatic fashion (evocative of Feynman diagrams). Despite the absence of any small parameter (like the QED alpha), the higher-order diagrams are suppressed due to geometrical reasons. Hence, we find a perturbative scheme without a perturbation parameter.

Faculty and Postdocs are welcome.

- November 12

Keith Rehermann

Atomic Dark Matter

- November 19

Daniel Park

How anomalies make the world a better place (for theorists)

I will give a general review on anomalies in field theories and explain how they place constraints on theories with chiral matter. Then I will focus on a particular set of theories--six dimensional theories with minimal supersymmetry--and explain how anomalies restrict the landscape of such theories. In particular I will depict how one is able to identify interesting low-energy effective theories that can either be undiscovered string vacua or secretly inconsistent theories by using anomaly constraints.

Faculty and Postdocs are welcome.

- December 3

Chi-Ming Chan

Families of conformal fixed points of N=2 Chern-Simons-Matter Theories

I will give a review on the N=2 Chern-Simons-Matter Theories and some nonrenormalization theorems about it, especially the existence of a two-loop conformal moduli space. I will further prove a new nonrenormalization theorem showing that the conformal moduli space survive to all loop order. I will also provide a 4-loop check on this new nonrenormalization theorem. Then I will introduce and calculate the Zamolodchikov metric on the moduli space and talk about some properties of it.

Faculty and Postdocs are welcome.

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