Curious behavior of three-dimensional lattice Dirac operators coupled to a monopole background
We investigate numerically the effect of regulating fermions in the presence of singular background fields in three dimensions. For this, we couple free lattice fermions to a background compact U(1) gauge field consisting of a monopole-anti-monopole pair of magnetic charge ±Q separated by a distance s in a periodic L3 lattice, and study the low-lying eigenvalues of different lattice Dirac operators under a continuum limit defined by taking L → ∞ at fixed s/L. As the background gauge field is parity even, we look for a two-fold degeneracy of the Dirac spectrum that is expected of a continuum-like Dirac operator. The naive-Dirac operator exhibits such a parity-doubling, but breaks the degeneracy of the fermion-doubler modes for the Q lowest eigenvalues in the continuum limit. The Wilson-Dirac operator lifts the fermion-doublers but breaks the parity-doubling in the Q lowest modes even in the continuum limit. The overlap-Dirac operator shows parity-doubling of all the modes even at finite L that is devoid of fermion-doubling, and singles out as a properly regulated continuum Dirac operator in the presence of singular gauge field configurations albeit with a peculiar algorithmic issue.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1573868
- Alternate ID(s):
- OSTI ID: 1580268
- Report Number(s):
- BNL-212435-2019-JAAM; PRVDAQ; 094501
- Journal Information:
- Physical Review. D., Journal Name: Physical Review. D. Vol. 100 Journal Issue: 9; ISSN 2470-0010
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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