Search Talks

In 2013, Cachazo, He and Yuan discovered a remarkable framework for scattering amplitudes in Quantum Field Theory (QFT) which mixes the real, complex and tropical geometry associated to the moduli space of n points on the projective line, $M_{0,n}$. By duality, this moduli space has a twin moduli space of $n$ generic points in $P^{n-3}$, leading to dual realization of scattering amplitudes, using a generalization of the CHY formalism introduced in 2019 by Cachazo, Early, Guevara and Mizera (CEGM). Any duality begs for an explanation! And, what physical phenomena lie between the twin moduli spaces? CEGM developed a framework to answer the question for moduli spaces of $n$ points in any $P^{k-1}$, leading to the discovery of rich, recursive structures and novel behaviors which portend an extension of QFT. We discuss recent joint works with Cachazo and Zhang, and with Geiger, Panizzut, Sturmfels, Yun, in which we dig deeper into some of the many mysteries which arise.

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Zoom link: https://pitp.zoom.us/j/95706337178?pwd=cnBka3lFWDBoRlFZV1VadXdGZ1JnZz09

Quantum Hall phases are the most exotic experimentally established quantum phases of matter.Recently they have been discovered at zero external magnetic field in two dimensional moire materials. I will describe recent work (with Xue-Yang Song and Ya-Hui Zhang) on their proximate phases and associated phase transitions that is motivated by the high tunability of thede moire systems. These phase transitions (and some of the proximate phases) are exotic as well, and realize novel ‘beyond Landau’ criticality that have been explored theoretically for many years. I will show that these moiré platforms provide a great experimental opportunity to study these unconventional phase transitions and related unconventional phases, thereby opening a new direction for research in quantum matter.

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Zoom link : https://pitp.zoom.us/j/97483204701?pwd=S2x4ck9tNHFjM0RiTDNWNFhaMk9SUT09

 I will present a galaxy formation model within the Lambda Cold Dark Matter (LCDM) framework that is calibrated on the results of galaxy formation simulations and some of the empirical properties of nearby dwarf galaxies. I will then use the model to interpret a number of ostensible challenges to the LCDM framework, such as the "too-big-too-fail problem", "central density problem" and the "planes of satellites" problem and will argue that none of these pose a serious challenge to LCDM, as the corresponding observations can be largely understood within the current galaxy formation modeling. I will also show that the same galaxy formation model can explain the abundance of UV-bright galaxies at z>5 measured by the Hubble Space Telescope and James Webb Space Telescope recently, if the expected increase of burstiness of star formation in galaxies towards early epochs is taken into account.

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Zoom link https://pitp.zoom.us/j/91798519705?pwd=Nk9rM0tFSXcrWDhLdXFhVmJWbGgvUT09