Spontaneous symmetry breaking in superfluid helium-4

Schwartz IV - 4 : Spontaneous symmetry breaking

Spontaneous symmetry breaking is one of the most important concepts in quantum field theory. The distinction between spontaneous and explicit symmetry breaking is that, with spontaneous symmetry breaking the Lagrangian is invariant under the symmetry, but the ground state of the theory is not. With explicit symmetry breaking, there was never an exact symmetry to begin with. One usually associat...

Electrons in Superfluid Helium-4

We review the current status of theory and experiment concerning electrons in superfluid helium-4 with an emphasis on some of the unsolved problems. Although calculations of the bubble structure have been confirmed in detail by measurements of the optical absorption spectrum, the energy of interaction of a bubble with a vortex is not understood. We discuss the theory behind a proposed experimen...

Nonperturbative Spontaneous Symmetry Breaking

One of the most astonishing results of quantum field theory is spontaneous symmetry breaking. One can say that it is the situation when something arises from the quantization. This means that on the quantum level one has something that was not present on the classical level. Coleman and Weinberg [1] write : “ . . . higher-order effects may qualitatively change the character of a physical theory...

Spontaneous Symmetry Breaking

Solitons and Spontaneous Symmetry Breaking in 2 and 4 Dimensions

We show that mass generation in 1+1 and 3+1 dimensions may occur together with spontaneous symmetry breaking. 1. Thirring model in the chirally broken phase Skyrme’s conjectured [1] that the solitons of the sine-Gordon model have the properties of fermions and couple by an interaction of the Thirring model type. The sine-Gordon model is a model of a bosonic field θ(x) in 1+1–dimensional space–t...