Applications

We have a few ready-to-use applications for some basic physics calculations. If you make a new application, please make sure it starts with main_.

main_getBeta.py

Given a reference scale, $N_\tau$, and $T$ in [MeV], this script calculates the corresponding $\beta$. An example calling is

./main_getTempandSpacing.py --Nt 8 --scale r0 --T 300 

main_getTempAndSpacing.py

Given a reference scale, $N_\tau$, and $\beta$ value, this script calculates $T$ in [MeV] and $a$ in [fm]. An example calling is

./main_getTempandSpacing.py --Nt 8 --beta 6.285 --scale fk

For more details about the scale setting, please look into the reference scales article.

main_HRG_measure.py

The goal of this script is to calculate some observables in the HRG model given some external control parameters, like a range of temperatures with fixed $\mu_B/T$. By default, this program uses a list of hadrons and resonances created by the HotQCD collaboration called QMHRG2020. You can find this list here:

latqcdtools/physics/HRGtables/hadron_list_ext_strange_2020.txt

A list that includes charmed hadrons and resonances is

latqcdtools/physics/HRGtables/hadron_list_ext_strange_charm_2020.txt

You can choose your hadron list with the --hadron_file argument. It is also up to you to choose a model; at the moment the only possibilities are the typical HRG QM or an excluded volume HRG model EV. This is specified with the argument --model. Finally you need to specify your observable --obs. If you specify a generalized susceptibility chi, you must also pass the $B$, $Q$, $S$, and $C$ chemical potential derivative orders. A straightforward usage of this script is, for instance,

./main_HRG_measure.py --obs chi --bqsc 1100 --temperature_range 130:180:0.5 --muB 0.0

main_HRG_LCP.py

In the context of QCD at finite chemical potential, it is interesting to examine systems following a few lines of constant physics (LCPs). The HotQCD collaboration has focused on strangeness-neutral systems, with $n_Q/n_B=0.4$ (corresponding to gold-gold collisions at RHIC) and $n_Q/n_B=0.5$ (corresponding to the isospin-symmetric case). This script creates tables of $\mu_B/T$, $\mu_Q/T$, and $\mu_S/T$ ($\mu_C=0$) that lie on $n_S=0$ LCPs like the ones mentioned above. A straightforward usage of this script is, for instance,

./main_HRG_LCP.py --r 0.4 --models QM --T 150

Once you have generated some LCP files, you can also use main_HRG_measure.py from above to carry out measurements on them. In such a case, you must pass the LCP file as argument. For instance,

./main_HRG_measure.py --obs chi --bqsc 1100 --LCP_file HRG_LCP_T150.0_r0.5QM

main_plotRatApprox.py

The RHMC of SIMULATeQCD relies on a rational approximation to the fermion determinant. It is useful to see how well this approximation compares with the exact function. This can be checked visually with, for example

./main_plotRatApprox.py in.rational 0.001 0.01

where in.rational is the rational approximation file, and we use a light quark mass of 0.001 in lattice units and a strange quark mass of 0.01.

main_HotQCDEoS.py

The paramterization for HotQCD equation of state at $\mu_B/T = 0$, $\mu_Q/T = 0$, and $\mu_S/T = 0$ are given in “Equation of state in ( 2+1 )-flavor QCD, Phys.Rev.D 90 (2014) 094503, (HotQCD Collaboration) A. Bazavov et al.”. The pressure ($P$), energy density ($\epsilon$) and entropy density ($s$) can be obtained from the thermodynamic relations.

./main_HotQCDEoS.py --EosType "fixedmuB" --muBdivT 0.0