Continuum limit of the mobility edge and taste-degeneracy effects in high-temperature lattice QCD with staggered quarks

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Main Authors: Bonanno, Claudio, Giordano, Matteo
Format: Preprint
Published: 2023
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author Bonanno, Claudio
Giordano, Matteo
author_facet Bonanno, Claudio
Giordano, Matteo
contents We study the effects of taste degeneracy on the continuum scaling of the localization properties of the staggered Dirac operator in high-temperature QCD using numerical simulations on the lattice, focusing in particular on the position of the mobility edge separating localized and delocalized modes at the low end of the spectrum. We find that, if the continuum limit is approached at fixed spatial volume, the restoration of taste symmetry leads to sizeable systematic effects on estimates for the mobility edge obtained from spectral statistics, which become larger and larger as the lattice spacing is decreased. Such systematics, however, are found to decrease if the volume is increased at fixed lattice spacing. We argue that spectral statistics estimate correctly the position of the mobility edge in the thermodynamic limit at fixed spacing, and support this with an independent numerical analysis based directly on the properties of the Dirac eigenvectors, that are unaffected by taste degeneracy. We then provide a theoretical argument justifying the exchange of the thermodynamic and continuum limits when studying localization. This allows us to use spectral statistics to determine the position of the mobility edge, and to obtain a controlled continuum extrapolation of the mobility edge for the first time.
format Preprint
id arxiv_https___arxiv_org_abs_2312_02857
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Continuum limit of the mobility edge and taste-degeneracy effects in high-temperature lattice QCD with staggered quarks
Bonanno, Claudio
Giordano, Matteo
High Energy Physics - Lattice
Disordered Systems and Neural Networks
We study the effects of taste degeneracy on the continuum scaling of the localization properties of the staggered Dirac operator in high-temperature QCD using numerical simulations on the lattice, focusing in particular on the position of the mobility edge separating localized and delocalized modes at the low end of the spectrum. We find that, if the continuum limit is approached at fixed spatial volume, the restoration of taste symmetry leads to sizeable systematic effects on estimates for the mobility edge obtained from spectral statistics, which become larger and larger as the lattice spacing is decreased. Such systematics, however, are found to decrease if the volume is increased at fixed lattice spacing. We argue that spectral statistics estimate correctly the position of the mobility edge in the thermodynamic limit at fixed spacing, and support this with an independent numerical analysis based directly on the properties of the Dirac eigenvectors, that are unaffected by taste degeneracy. We then provide a theoretical argument justifying the exchange of the thermodynamic and continuum limits when studying localization. This allows us to use spectral statistics to determine the position of the mobility edge, and to obtain a controlled continuum extrapolation of the mobility edge for the first time.
title Continuum limit of the mobility edge and taste-degeneracy effects in high-temperature lattice QCD with staggered quarks
topic High Energy Physics - Lattice
Disordered Systems and Neural Networks
url https://arxiv.org/abs/2312.02857