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

\(N_\tau\)
128
64
56
48
40
36
32
28
24*
20*
16*
12
8

\(T\) MeV
47
95
109
127
152
169
190
217
253
304
380
507
760

\(T / T_{c}\)
0.284
0.569
0.650
0.758
0.910
1.011
1.138
1.300
1.517
1.820
2.275
3.034
4.550

\(N_{cfg}\)
1024
1041
1042
1123
1102
1119
1090
1031
1016
1030
1102
1267
1048

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/