Speaker
Description
Gapless Dirac fermions appear as low-energy excitations in many condensed matter systems of recent interest. They are often weakly interacting, as famously in graphene, but at stronger interactions they can also acquire a gap ("mass") and exhibit many ordered ground states by going through phase transitions at which gapless Dirac fermions play a crucial role. Prime example of this occurs in the Hubbard model on honeycomb lattice at half filling, which suffers a "relativistic Mott transition" from gapless semimetal to gapped insulator, believed to be observed recently in twisted multilayers.
I will discuss the recent unification of all order parameters for Dirac systems in two dimensions based on large hidden orthogonal symmetry of free Dirac fermions. Interestingly, the unique interacting field theory that respects such an orthogonal symmetry turns out to be equivalent to the celebrated Gross-Neveu model. I will argue that, in spite of recently turning 50, this model still has a large, unexplored, and surprisingly interesting region of its coupling constant. Recent analytical and numerical results relevant to this "dark side" of the Gross-Neveu model will be presented.
| Affiliation | Simon Fraser University |
|---|---|
| Career status | Senior |