FASTSUM Generation 2L Anisotropic Thermal Lattice QCD Gauge Ensembles

FASTSUM Generation 2L Anisotropic Thermal Lattice QCD Gauge Ensembles

The FASTSUM collaboration [1] Generation 2L Ensembles are lattice Quantum Chromodynamics (QCD) gauge-ensembles used extensively to examine thermal (non-zero temperature) properties of QCD using the first principles methods of lattice QCD. These are anisotropic lattices using the `fixed-scale` approach to thermal ensembles wherein the temperature is changed entirely by changing the number of points in the temporal direction. These ensembles have a quark mass closer to physical than our earlier Generation 2 Ensembles.

These ensembles are available (see below) for non-competing research. The requirements of this use are that this Zenodo page, and the two papers detailing the ensembles, Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark  and Open charm mesons at nonzero temperature: results in the hadronic phase from lattice QCD are appropriately cited.

These ensembles are characterised by

• \(N_f = 2  +1 \) flavour
  • Degenerate up and down quarks, approximately physical strange quark
• spatial lattice spacing \(a_s\)
  • ~0.112 fm
• temporal lattice spacing \(a_t\)
  • ~0.033 fm
• anisotropy \(\nu = a_s / a_t\)
  • ~3.453
• Number of spatial sites NS
  • NS = 32
• Number of Temporal sites
  • NT in [8, 128]
• Temperatures
  • 47 MeV to 760 MeV
• Pseudocritical temperature (from renormalised chiral condensate)
  • 167(3) MeV
• Pion mass
  • \(m_\pi \sim 239\) MeV

This choice action and bare parameters follows that of the Hadron Spectrum Collaboration https://doi.org/10.1103/PhysRevD.78.054501, namely a Symanzik improved gauge action and a tadpole improved Wilson-clover fermion action with stout-smeared links. 

The main parameters in the lattice action are listed below. The bare fermion anisotropy \(\gamma_f\) is obtained by \(\gamma_f = \gamma_g / \nu\). Full details may be found in Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark  and Open charm mesons at nonzero temperature: results in the hadronic phase from lattice QCD which are also attached to this record.

• gauge coupling
  • \(\beta = 1.5\)
• tree-level coefficients
  • \(c_0 = 5/3,\, c2=-1/12\)
• bare gauge, fermion anisotropy
  • \(\gamma_g = 4.3,\, \gamma_f = 3.399\)
• ratio of bare anisotropies
  • \(\nu = \gamma_g / \gamma_f = 1.265\)
• spatial tadpole (without, with smeared links)
  • \(u_s = 0.733566, \tilde{u}_s = 0.92674\)
• temporal tadpole (without, with smeared links)
  • \(u_\tau =1, \tilde{u}_\tau =1\)
• stout smearing for spatial links
  • isotropic, 2 steps, \(\rho = 0.14\)
• bare light quark mass
  • \(m_0^l = -0.0860\)
• bare strange quark mass
  • \(m^s_0 = -0.0743\)
• light quark hopping parameter
  • \(\kappa_{light} = 0.27831\)
• strange quark hopping parameter
  • \(\kappa_{strange} = 0.2765\)

The available ensembles are detailed in the below table

The ensembles marked by * also have ~100 configurations at \(N_S = 48\).

Sharing & Usage

The ensembles are currently available for non-competing research. To enquire, please contact  (preferably) the generic email address PhysicsByFASTSUM AT gmail DOT com or one of Chris Allton or Jon-Ivar Skullerud.

If they are used, this Zenodo page and two papers detailing the ensembles, Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark  and Open charm mesons at nonzero temperature: results in the hadronic phase from lattice QCD must be appropriately cited, i.e. with bibtex

@article{PhysRevD.105.034504,
  title = {Properties of the QCD thermal transition with ${N}_{f}=2+1$ flavors of Wilson quark},
  author = {Aarts, G. and Allton, C. and Glesaaen, J. and Hands, S. and J\"ager, B. and Kim, S. and Lombardo, M. P. and Nikolaev, A. A. and Ryan, S. M. and Skullerud, J.-I. and Wu, L.-K.},
  journal = {Phys. Rev. D},
  eprint = "2007.04188",
  archivePrefix = "arXiv",
  primaryClass = "hep-lat",
  volume = {105},
  issue = {3},
  pages = {034504},
  numpages = {12},
  year = {2022},
  month = {Feb},
  publisher = {American Physical Society},
  doi = {10.1103/PhysRevD.105.034504},
  url = {https://link.aps.org/doi/10.1103/PhysRevD.105.034504}
}  

and

@article{Aarts:2022krz,
    author = {Aarts, Gert and Allton, Chris and Bignell, Ryan and Burns, Timothy J. and Garc\'\i{}a-Mascaraque, Sergio Chaves and Hands, Simon and J\"ager, Benjamin and Kim, Seyong and Ryan, Sin\'ead M. and Skullerud, Jon-Ivar},
    title = "{Open charm mesons at nonzero temperature: results in the hadronic phase from lattice QCD}",
    eprint = "2209.14681",
    archivePrefix = "arXiv",
    primaryClass = "hep-lat",
    month = "9",
    year = "2022"
}

[1] https://fastsum.gitlab.io/