Reference scales and physical constants

Scale setting

In the module

latqcdtools.physics.referenceScales

you find lots of functions for scale setting, along with references for each scale determination. Supported scales include: \(f_K\), \(t_0\), \(r_0\), \(r_1\), and \(r_1m_s\).

You can get scales in lattice units through methods like a_times_fk(beta: float, year), which takes the bare coupling as input and returns \(a\,f_K(\beta)\) using a parameterization specified by the year year. In this particular instance, there exists parameterizations from 2021, 2014, and 2012. Please note that the parameterizations for \(a\) have closed intervals \([\beta_{\rm min},~\beta_{\rm max}]\) in which they are valid.

Physical constants

In the module

latqcdtools.physics.constants

one finds many constants of nature. In general these have the form

M_rho_phys(year=2022,units="MeV",returnErr=False)

The default year is the most recent measurement the authors have implemented. This number is usually taken from the PDG, but it may be taken from other papers. We always try to list the source of the measurement. If returnErr=True, this will return a tuple of the form mean, error. The list of included physical constants expands as our authors work on more and more projects.

What you might also find helpful in this module is a method for conversion between many kinds of units. This is carried out with

convert(x,unit1,unit2)

which converts the number x from unit1 to units unit2. Note that unit1 and unit2 know about scientific prefixes. This includes some of the standard conversions in high energy physics, like fm to MeV\(^{-1}\). But there are also time units in case you work on something touching cosmology and energy units in case you want to optimize your electricity bill.