Time-reversal breaking in QCD 4 , walls, and dualities in 2 + 1 dimensions

We study SU(N ) Quantum Chromodynamics (QCD) in 3+1 dimensions with Nƒ degenerate fundamental quarks with mass m and a θ-parameter. For generic m and θ the theory has a single gapped vacuum. However, as θ is varied through θ = π for large m there is a first order transition. For Nƒ = 1 the first order transition line ends at a point with a massless η' particle (for all N ) and for Nƒ > 1 the first order transition ends at m = 0, where, depending on the value of Nƒ, the IR theory has free Nambu-Goldstone bosons, an interacting conformal field theory, or a free gauge theory. Even when the 4d bulk is smooth, domain walls and interfaces can have interesting phase transitions separating…

• UD
  U.S. Department of Energy

  Awards: DE-SC0009988, SC0009988
• GO
  Government of Canada
• IC
  Industry Canada
• MD
  Ministero dello Sviluppo Economico
• IP
  Institut Périmètre de physique théorique
• IC
  Israeli Centers for Research Excellence

  Award: 1937/12
• PA
  Planning and Budgeting Committee of the Council for Higher Education of Israel

  Award: 1937/12