Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model

We revisit the lattice formulation of the Schwinger model using the Kogut-Susskind Hamiltonian approach with staggered fermions. This model, introduced by Banks et al. Phys. Rev. D 13, 1043 (1976)10.1103/PhysRevD.13.1043, contains the mass term m_{lat}∑_{n}(−1)^{n}χ_{n}^{†}χ_{n}, and setting it to z...

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Main Authors: Ross Dempsey, Igor R. Klebanov, Silviu S. Pufu, Bernardo Zan
Format: Article
Language:English
Published: American Physical Society 2022-11-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.4.043133
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author Ross Dempsey
Igor R. Klebanov
Silviu S. Pufu
Bernardo Zan
author_facet Ross Dempsey
Igor R. Klebanov
Silviu S. Pufu
Bernardo Zan
author_sort Ross Dempsey
collection DOAJ
description We revisit the lattice formulation of the Schwinger model using the Kogut-Susskind Hamiltonian approach with staggered fermions. This model, introduced by Banks et al. Phys. Rev. D 13, 1043 (1976)10.1103/PhysRevD.13.1043, contains the mass term m_{lat}∑_{n}(−1)^{n}χ_{n}^{†}χ_{n}, and setting it to zero is often assumed to provide the lattice regularization of the massless Schwinger model. We instead argue that the relation between the lattice and continuum mass parameters should be taken as m_{lat}=m−1/8e^{2}a. The model with m=0 is shown to possess a discrete chiral symmetry that is generated by the unit lattice translation accompanied by the shift of the θ angle by π. While the mass shift vanishes as the lattice spacing a approaches zero, we find that including this shift greatly improves the rate of convergence to the continuum limit. We demonstrate the faster convergence using both numerical diagonalizations of finite lattice systems, as well as extrapolations of the lattice strong coupling expansions.
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spelling doaj.art-55f0fe123e98428e9f0bea5fafe538802024-04-12T17:26:32ZengAmerican Physical SocietyPhysical Review Research2643-15642022-11-014404313310.1103/PhysRevResearch.4.043133Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger modelRoss DempseyIgor R. KlebanovSilviu S. PufuBernardo ZanWe revisit the lattice formulation of the Schwinger model using the Kogut-Susskind Hamiltonian approach with staggered fermions. This model, introduced by Banks et al. Phys. Rev. D 13, 1043 (1976)10.1103/PhysRevD.13.1043, contains the mass term m_{lat}∑_{n}(−1)^{n}χ_{n}^{†}χ_{n}, and setting it to zero is often assumed to provide the lattice regularization of the massless Schwinger model. We instead argue that the relation between the lattice and continuum mass parameters should be taken as m_{lat}=m−1/8e^{2}a. The model with m=0 is shown to possess a discrete chiral symmetry that is generated by the unit lattice translation accompanied by the shift of the θ angle by π. While the mass shift vanishes as the lattice spacing a approaches zero, we find that including this shift greatly improves the rate of convergence to the continuum limit. We demonstrate the faster convergence using both numerical diagonalizations of finite lattice systems, as well as extrapolations of the lattice strong coupling expansions.http://doi.org/10.1103/PhysRevResearch.4.043133
spellingShingle Ross Dempsey
Igor R. Klebanov
Silviu S. Pufu
Bernardo Zan
Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
Physical Review Research
title Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
title_full Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
title_fullStr Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
title_full_unstemmed Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
title_short Discrete chiral symmetry and mass shift in the lattice Hamiltonian approach to the Schwinger model
title_sort discrete chiral symmetry and mass shift in the lattice hamiltonian approach to the schwinger model
url http://doi.org/10.1103/PhysRevResearch.4.043133
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