Phase diagram of 1+1D Abelian-Higgs model and its critical point

Understand

We determine the phase diagram of the Abelian-Higgs model in one spatial dimension and time (1+1D) on a lattice.

• We identify a line of first order phase transitions separating the Higgs region from the confined one.
• This line terminates in a quantum critical point above which the two regions are connected by a smooth crossover.
• We analyze the critical point and find compelling evidences for its description as the product of two non-interacting systems, a massless free fermion and a massless free boson.