New QCD Parameter Determinations

[ohwilleke]

TL;DR Summary

A pair of new papers make precision determinations of the quark masses and the strong force coupling constant using the renormalization group summed perturbation theory (RGSPT). The values are close to previous estimates, but there is some tension in the strange quark mass determination.

A pair of new papers (here and here) make precision determinations of the quark masses and the strong force coupling constant using the renormalization group summed perturbation theory (RGSPT). For comparison purposes, I have followed each value with the Particle Data Group (PDG) value, and then the 2021 Flavor Lattice Averaging Group (FLAG) value.

α(s)(n(f)=5)(M(Z)) = 0.1171(7)
<----> 0.1179(9) <----> 0.1184(8).

m_b(MS mass pole mass) = 4174.3(9.5) MeV
<----> 4180-20+30 MeV <----> 4203(11) MeV

m_c(MS mass pole mass) = 1281.1(3.8) MeV
<----> 1270(20) MeV <----> 1278(13) MeV

m_s(2 GeV) = 104.34-4.21+4.23 MeV
<----> 93.4-3.4+8.6 MeV <----> 93.44(68) MeV

m_d(2 GeV) = 4.21-0.45+0.48 MeV
<----> 4.67-0.17+0.48 MeV <----> 4.70(5) MeV

m_u(2 GeV) = 2.00-0.40+0.33 MeV
<----> 2.16-0.26+0.49 MeV <----> 2.14(8) MeV

Can anyone explain, at an educated layman's "intermediate" level, why the strange quark mass value in this method has more tension than the other parameters do with previously estimated values?

My gut intuition is that the tension is due to insufficient consideration of non-perturbative effects by RGSPT, which turns out to be maximal for the strange quark, but I don't have a well substantiated basis for that hypothesis.

 

[malawi_glenn]

what does

<---->mean?

 

[ohwilleke]

what does

<---->mean?

I'm merely using it as a way to visually distinguish between the values from each of the three sources for each parameter, while connecting all three values to the definition of the parameter described (which would ideally all appear on the same line).

If you use of comma or semi-colon, they tend to visually blend into each other to my tired middle aged bifocal wearing eyes.

If you you separate lines for each entry, it gets harder to read the post as a whole, since it has six more lines.

 

[malawi_glenn]

table	works	fine	too
the	<---->	is	garbage

personally	I	think
the	lack	of
## \LaTeX ##	formation	is

even	more
hurtful	to

eyes