The FLAG 2024 Report

FLAG, i.e., the Flavour Averaging Lattice Group, is a collaboration of scientists who generally also have primary employment elsewhere (much like the Particle Data Group) that compiles and analyzes experimental results in lattice QCD and updates these results periodically, to determine the bottom line values of Standard Model fundamental physical constants and also the experimentally measured values of a variety of other physical constants that could in principle be calculated from first principles in the Standard Model.

FLAG is generally more bold in terms of reaching precise values for constants, by being willing to be less methodology and outlier agnostic than the Particle Data Group.

Some select results

* Quark masses (in the MS bar scheme in a 2+1+1 scheme, at pole mass for bottom and charm quarks and a 2 GeV energy scale for the three light quark masses, followed by comparable PDG estimates):

u quark mass: 2.14 ± 0.18 MeV  v. 2.16 ± 0.07 MeV

d quark mass: 4.70 ± 0.05 MeV v. 4.70 ± 0.07 MeV

s quark mass: 93.44 ± 0.68 MeV v. 93.5 ± 0.8 MeV

c quark mass: 1280 ± 12 MeV v. 1273.0 ± 4.6 MeV

b quark mass: 4200 ± 14 MeV v. 4183 ± 7 MeV

* CKM matrix elements from global Standard Model fits:

|V(ud)|: 0.97439(14)

|V(us)|: 0.22483(61)

|V(ub)|: 0.00382(24)

* The strong force coupling constant alpha(s) in a five quark model in the MS bar scheme at the Z boson mass:

0.1183(7)

Combining FLAG and PDG non-lattice estimates:

0.1181(7)

For comparison sake, here are the world average measured values of some other Standard Model Constant values (per the Particle Data Group):

t quark mass direct measurements 172,570 ± 290 MeV (S=1.5)

t quark pole mass cross-section measurements 172,400 ± 700 MeV (S=1.1)

Electron mass 0.051099895000 ± 0.00000000015 MeV

Muon mass 105.6583755 ± 0.0000023 MeV

Tau lepton mass 1,776.93 ± 0.09 MeV

The Koide rule prediction of the tau lepton mass is 1,776.96894(7) MeV.

W boson mass 80,369.2 ± 13.3 MeV

The electroweak fit value of the W boson mass is 80,360.2 ± 9.9 MeV.

Z boson mass 91,188 ± 2 MeV

SM Higgs boson mass 125,200 ± 110 MeV

The full CKM matrix in a global fit per PDG (which differ from the FLAG values above):

The CKM matrix (and the PMNS matrix) can be completely summarized with four parameters (although there is more than one way to choose those four parameters).

Fermi coupling constant (G(F)/(h(bar)*c)^3, a derived version of weak force coupling constant) 0.000011663788(6) GeV^-2

Fine structure constant (i.e. electromagnetic force coupling constant) at a near zero energy scale is 0.0072973525693(11) 

I'll omit Planck's constant, the speed of light, and the physical constants related to neutrinos (the PMNS matrix and the three neutrino masses). I'll also omit the two fundamental physical constants related to gravity (Newton's constant and the cosmological constant).

Citation details are below the fold.

Their 2024 annual report, which is 435 pages long, is now available. The abstract is as follows:

We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor f(+)(0) arising in the semileptonic K→π transition at zero momentum transfer, as well as the decay-constant ratio f(K)/f(π) and its consequences for the CKM matrix elements V(us) and V(ud). 

We review the determination of the B(K) parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. 

For the heavy-quark sector, we provide results for m(c) and m(b) as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. 

We review the status of lattice determinations of the strong coupling constant α(s). 

We review the determinations of nucleon charges from the matrix elements of both isovector and flavour-diagonal axial, scalar and tensor local quark bilinears, and momentum fraction, helicity moment and the transversity moment from one-link quark bilinears. 

We also review determinations of scale-setting quantities. 

Finally, in this review we have added a new section on the general definition of the low-energy limit of the Standard Model.