First-Principles Simulations of 1+1D Quantum Field Theories at θ=π and Spin Chains

Area of Science:

• * Theoretical Physics
• * Quantum Field Theory
• * Computational Physics

Background:

• * Simulating U(1) gauge-Higgs models with topological terms, particularly at θ=π, is challenging due to the sign problem in standard lattice formulations.
• * The sign problem significantly increases computational costs, hindering reliable ab initio studies.

Purpose of the Study:

• * To overcome the sign problem in lattice simulations of a 2-flavor U(1) gauge-Higgs model with a topological term at θ=π.
• * To reliably simulate such systems and determine their universality class.
• * To demonstrate the efficacy of a novel discretization and dualization approach for U(1) gauge theories.

Main Methods:

• * Development and application of a novel discretization for the U(1) gauge-Higgs model.
• * Utilizing exact lattice dualization to circumvent the sign problem.
• * Performing ab initio lattice simulations to analyze the model's properties.

Main Results:

• * Successfully overcame the sign problem, enabling reliable simulations.
• * Provided the first ab initio demonstration that the model belongs to the spin-chain universality class.
• * Showcased the power and effectiveness of the new simulation approach for U(1) gauge theories.

Conclusions:

• * The novel lattice discretization and dualization method effectively resolves the sign problem in U(1) gauge-Higgs models.
• * The 2-flavor U(1) gauge-Higgs model with a topological term at θ=π is confirmed to be in the spin-chain universality class.
• * This work establishes a powerful new tool for studying U(1) gauge theories computationally.