FASTSUM Generation 2 Anisotropic Thermal Lattice QCD Gauge Ensembles

FASTSUM Generation 2 Anisotropic Thermal Lattice QCD Gauge Ensembles

The FASTSUM collaboration [1] Generation 2 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 are freely available (see below). The only requirements of use are that this Zenodo page, and the two papers detailing the ensembles, Electrical conductivity and charge diffusion in thermal QCD from the lattice and Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark are appropriately cited.

These ensembles are characterised by

\(N_f = 2  +1 \) flavour

Degenerate up and down quarks, physical strange quark

spatial lattice spacing \(a_s\)

~0.12 fm

temporal lattice spacing \(a_t\)

~0.035 fm

anisotropy \(\nu = a_s / a_t\)

~3.444

Number of spatial sites NS

NS = 24 or 32

Number of Temporal sites

NT in [16, 48]

Temperatures

117 MeV to 352 MeV

Pseudocritical temperature (from renormalised chiral condensate)

181(1) MeV

Pion mass

\(m_\pi \sim 384\) MeV

Pseudoscalar to vector mass ratio

\( M_\pi / M_\rho \sim 0.446\)

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 Electrical conductivity and charge diffusion in thermal QCD from the lattice and Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark which are also attached to this Zenodo 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

\(m_0^l = -0.0840\)

bare strange quark mass

\(m^s_0 = -0.0743\)

light quark hopping parameter

\(\kappa_{light} = 0.2780\)

strange quark hopping parameter

\(\kappa_{strange} = 0.2765\)

The available ensembles are detailed in the below table

\(N_\tau\)
16
20
24
28
32
36
40
48

\(N_s\)
24, 32
24
24, 32
24, 32
24, 32
24
24
32

\(T\) MeV
352
281
235
201
176
156
141
117

\(T / T_{c}\)
1.900
1.520
1.267
1.086
0.950
0.844
0.760
0.633

\(N_{cfg}\)

1009*, 1172**

1000

1001, 502

1100^, 502
1000, 501
501
523^^
501

* Only 1000 in openQCD format

** Only 591 in openQCD format

^ Only 1001 in openQCD format

^^ Only 502 in openQCD format

Sharing & Usage

The ensembles are available on Storj, a decentralised cloud storage service. Our storage here is supported by DiRAC [2]. The available data may be viewed and downloaded via web browser or in an automated manner using the S3 interface to Storj [3].

To view the available data, and download via web browser, the HTTP interface may be used: https://link.storjshare.io/julj4eulkfnqnd26v36des6wvy3a/gen2-configs . To download in an automated manner the S3 interface to Storj may be used [3] with the following Access Key: 

jxejpzv46zrr3rfnoz66n5px2rca

and Secret Key

j2o44mi2a76zajpvyv5wjd2wgjqgncfagln6nf6jpwbv7o3npj7t6

with the gateway

https://gateway.storjshare.io

More details are available from  (preferably) the generic email address PhysicsByFASTSUM AT gmail DOT com or one of Chris Allton, Ryan Bignell and Jon-Ivar Skullerud.

We supply the gaugefields in at least one of ILDG (Chroma) format and openqcd format. Also supplied are log files, and chroma input files. The gaugefields were generated using Chroma and later converted to openqcd.

The ensembles are available for all uses. If they are used, this Zenodo page and two papers detailing the ensembles, Electrical conductivity and charge diffusion in thermal QCD from the lattice and Properties of the QCD thermal transition with Nf=2+1 flavors of Wilson quark must be appropriately cited, i.e. with bibtex

@article{Aarts:2014nba,
author = "Aarts, Gert and Allton, Chris and Amato, Alessandro and Giudice, Pietro and Hands, Simon and Skullerud, Jon-Ivar",
title = "{Electrical conductivity and charge diffusion in thermal QCD from the lattice}",
eprint = "1412.6411",
archivePrefix = "arXiv",
primaryClass = "hep-lat",
reportNumber = "HIP-2014-34-TH, INT-PUB-14-060, MS-TP-14-40",
doi = "10.1007/JHEP02(2015)186",
journal = "JHEP",
volume = "02",
pages = "186",
year = "2015"
}and@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},  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}}

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

[2] https://dirac.ac.uk/

[3] https://rclone.org/storj/