The CTP Lunch Club meets every Friday at noon in the Cosman seminar room, 6C-442 (provided that there are sufficient speakers). Pizza will be provided.

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, Anand Natarajan at anandn-at-mit[dot]edu and Srivatsan Rajagopal at srivat91-at-mit[dot]edu.

- February 20

Cyril Stark

Robustness of the Hilbert space dimension under measurement uncertainty

II will first motivate the search for algorithms to learn effective quantum models from the perspective of physics (analysis of experimental data), from the perspective of computer science (quantum communication complexity), and from the perspective of mathematical programming (extension complexity). I will then describe briefly recent joint work with Aram Harrow about the robustness (with respect to noise) of a key property of effective models, namely, the Hilbert space dimension (see arXiv:1412.7437).

- March 6

Wei Xue

Cosmic Ray Antiproton/Proton

Dark Matter indirect search is to find the signals of dark matter annihilation or decay from cosmic rays. In this talk, I will shortly review the current status of cosmic ray search on dark matter, and focus on the antiproton constraints and forecast its future sensitivities. As a compiling model, the scalar Higgs portal is able to provide a connection between the visible world and the dark sector via a renormalizable coupling with the Higgs boson. I will apply this model to illustrate the importance of antiproton constraints by comparing with other observations.

- March 13

Nima Lashkari

Relative entropy in conformal field theory

We introduce a replica trick that computes the relative entropy of any two states in field theory. This information proves to be sufficient to calculate arbitrary elements of the modular operator of all excited states. We perform sample calculations and discover a surprising connection between energy and vacuum distinguishability of states in conformal field theories.

- March 20

Yinan Wang

Generalized Cartan calculus and exceptional field theory

It's long known that maximal supergravity on torus has exceptional "hidden" symmetry. Exceptional field theory makes this symmetry manifest by introducing a higher dimensional extended space. The differential geometry in this extended space is different from the conventional one. We develop tensor calculus in this extended space. With this new method, the "tensor hierarchy" structure in exceptional field theory can be derived in a nice way.

- April 3

Ben Safdi

The Fermi GeV excess: annihilating dark matter or millisecond pulsars?

Data from the Fermi Large Area Telescope suggests that there is an extended excess of GeV gamma-ray photons in the Inner Galaxy. Identifying potential astrophysical sources that contribute to this excess is an important step in verifying whether the signal originates from annihilating dark matter. I will show that the statistics of the photons---in particular, the flux probability density function of the photon counts below the point-source detection threshold---can potentially distinguish between the dark-matter and point-source interpretations of the excess. I will describe preliminary results that arise from applying our statistical method to the Fermi data.

- April 17

Ian Moult

Jet Substructure and the Square Root of Alpha_s

With the start of the LHC, the past several years has seen a revolution in the types of questions which can be asked about QCD jets, in particular about their substructure. These questions are both important for optimizing many LHC searches, and as a playground for improving our understanding of QCD. This has motivated first principles QCD calculations of a variety of new QCD jet observables, some of which exhibit interesting behaviour. In this talk I will discuss a particular example of an observable, which emerges naturally when asking concrete questions about jet substructure at the LHC, but exhibits strange theoretical properties. In particular, it exhibits no expansion in the strong coupling constant, alpha_s, and is therefore not computable in fixed order perturbation theory. Nevertheless, I will describe how this observable can be computed in resummed perturbation theory, leading to an expansion in the square root of alpha_s.

- April 24 at 1:50pm

*Thesis defense

Yoni Kahn

Forces and Gauge Groups Beyond the Standard Model

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