#### Melting hadrons on the wall: from quantum magnets to QCD

- Event time: 2:00pm
- Event date: 15th May 2017
- Speaker: Tin Sulejmanpasic (École Normale Supérieure Paris)
- Location: Higgs Centre Seminar Room, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB

### Event details

I will discuss parallels between QCD-like theories in confining phase and quantum anti-ferromagnets in the Valence Bond Solid (VBS) phase. The VBS phase has confined spin 1/2 particles -- spinons, so that the true excitations are spin triplets -- "the hadrons" of the VBS phase. Much like quarks in QCD, spinons are not a part of the low-energy spectrum but their composits are. Generically the VBS has multiple ground states related by a discrete symmetry, and hence stable domain walls between these vacua exist. Similarly QCD-like theories such as QCD with adjoint matter or pure Yang-Mills at \theta=\pi topological angle, are believed to possess degenerate ground-states. I will argue that domain walls in the VBS as well as QCD-like theories generically deconfine the corresponding "quarks", melting away the "hadrons". While QCD-like theories often suffer from a sign problem resisting first-principle lattice analysis, the VBS is conducive to monte-carlo simulations and confirm this picture. I will further argue that the reason behind this deconfinement is the existence of the mixed 't Hooft anomalies between various symmetries of the setups.

The Particle Physics Theory seminar is a weekly series of talks reflecting the diverse interests of the group. Topics include analytic and numerical calculations based on the Standard Model of elementary particle physics, theories exploring new physics, as well as more formal developments in gauge theories and gravity..