Multiscale Monte Carlo equilibration: Two-color QCD with two fermion flavors
Name
PhysRevD.94.114502.pdf
Size
1.81 MB
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Adobe PDF
Checksum (MD5)
47112d8d2889a8e6c1cbb7e66d893ce7
Author(s)
Detmold, William
Endres, Michael G
Date Issued
December 2016
Journal
Physical Review D
Publisher
American Physical Society
Citation
Detmold, William, and Michael G. Endres. “Multiscale Monte Carlo Equilibration: Two-Color QCD with Two Fermion Flavors.” Physical Review D 94.11 (2016): n. pag. © 2016 American Physical Society
Version
Final published version
Abstract
We demonstrate the applicability of a recently proposed multiscale thermalization algorithm to two-color quantum chromodynamics (QCD) with two mass-degenerate fermion flavors. The algorithm involves refining an ensemble of gauge configurations that had been generated using a renormalization group (RG) matched coarse action, thereby producing a fine ensemble that is close to the thermalized distribution of a target fine action; the refined ensemble is subsequently rethermalized using conventional algorithms. Although the generalization of this algorithm from pure Yang-Mills theory to QCD with dynamical fermions is straightforward, we find that in the latter case, the method is susceptible to numerical instabilities during the initial stages of rethermalization when using the hybrid Monte Carlo algorithm. We find that these instabilities arise from large fermion forces in the evolution, which are attributed to an accumulation of spurious near-zero modes of the Dirac operator. We propose a simple strategy for curing this problem, and demonstrate that rapid thermalization—as probed by a variety of gluonic and fermionic operators—is possible with the use of this solution. In addition, we study the sensitivity of rethermalization rates to the RG matching of the coarse and fine actions, and identify effective matching conditions based on a variety of measured scales.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.94.114502
