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Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
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Symmetric Mass Generation with Four SU(2) Doublet Fermions
Nouman Butt1, Simon Catterall2, Anna Hasenfratz3
1University of Illinois, Department of Physics, Urbana-Champaign, Illinois, USA.
Physical Review Letters
|February 10, 2025
Summary
Researchers explored an SU(2) gauge theory with massless fermions. A new symmetric mass generation (SMG) phase was discovered at strong coupling, exhibiting confinement and unbroken chiral symmetry.
Area of Science:
- High Energy Physics
- Quantum Field Theory
- Lattice Gauge Theory
Background:
- Studying SU(2) gauge theories is crucial for understanding fundamental forces.
- Investigating massless fermions reveals critical properties of quantum chromodynamics (QCD) and beyond.
- Lattice gauge theory provides a non-perturbative framework to study strongly coupled systems.
Purpose of the Study:
- To explore the phase diagram of an SU(2) gauge theory with a single massless fermion.
- To characterize the novel phase appearing at strong coupling.
- To determine the nature of the phase transition and its implications for the conformal window.
Main Methods:
- Utilizing an nHYP-smeared fermion action on the lattice.
- Employing additional heavy Pauli-Villars fields to reduce lattice artifacts.
- Performing finite size scaling analysis and studying renormalization group flows.
Main Results:
- A two-phase structure was identified: a conformal phase at weak coupling and a symmetric mass generation (SMG) phase at strong coupling.
- The SMG phase is characterized by confinement, gapped states, and unbroken chiral symmetry.
- Finite size scaling analysis indicates a continuous phase transition between the conformal and SMG phases.
Conclusions:
- The findings suggest the existence of a continuum SMG phase.
- Renormalization group flows are consistent with a vanishing beta function, indicating a potential new fixed point.
- This SU(2) gauge theory with N_f=4 flavors may lie at the edge of the conformal window.
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