A new paper makes some of the most precise determinations ever of the b, c, and s quark masses. The new paper takes into account quantum electrodynamics (QED) corrections (which is ignored in most quark mass determinations), and the unequal u quark v. d quark masses. It disregards, however, the vacuum polarization contribution of the b quark in its c and s quark mass determinations.
The determined b quark pole mass of 4.1911(62) GeV in the new paper compares to a Particle Data Group world average value of 4.1830(40) GeV which is consistent at the 1.1 sigma level. This should slightly pull up the PDG world average.
The new paper's c quark and s quark mass determinations in the abstract are at the unconventional 3 GeV energy scale in a 4 flavor QCD determination (which ignores b quark effects since the energy scales in question are below the b quark mass). These are m(c) = 0.9808(33) GeV, and m(s) = 83.34(26) MeV, which are lower than the values at the conventional energy scales, because the running of the quark masses with higher energies is towards smaller masses.
Normally, the c quark mass is quoted as a pole mass with the Particle Data Group world average c quark pole mass of 1.2730(28) GeV. The beta function of this experimentally determined Standard Model constants from 3 GeV to the pole mass, give an c quark pole mass in the new paper of 1.2712(82) GeV which is consistent at the 0.2 sigma level. This should slightly pull down the PDG value.
The s quark mass is normally quoted at 2 GeV with the Particle Data Group world average s quark mass at 2 GeV of 93.50(80) MeV. The beta function of this experimentally determined Standard Model constants from 3 GeV to 2 GeV, gives an s quark mass at the 2 GeV energy scale in the new paper of 92.32(42) MeV which is consistent at the 1.3 sigma level and about twice as precise as the current world average from only a single determination. This should significantly pull down the PDG value. This also confirms definitively (at 32 sigma) that the s quark is less massive than the muon (which is 105.6583755(23) MeV), something that has only been definitively established in the last few years.
Each of the new measurements (but especially the s quark mass determination) should lower the uncertainty in the world average (although the c and s quark mass estimates from the PDG already adjust up the uncertainty in their sources that go into their inverse error weighted averages by 1.2 and 1.1 respectively).
We extend an earlier lattice QCD analysis of heavy-quark current-current correlators to obtain new values for the MS masses of the b, c, and s quarks. The analysis uses gluon configurations from the MILC collaboration with vacuum polarization contributions from u, d, s, and c quarks (nf = 4), and lattice spacings down to 0.032 fm. We find that m(b)(m(b), nf = 5) = 4.1911(62) GeV, m(c)(3 GeV, nf = 4) = 0.9808(33) GeV, and m(s) (3 GeV, nf = 4) = 83.34(26) MeV.
These results are corrected for QED by including (quenched) QED in the simulations. They are among the most accurate values by any method to date. We give a detailed analysis of finite lattice-spacing errors that shows why the HISQ discretization of the quark action is particularly useful for b-quark simulations even for lattices where am(b) ≈ 1. We also calculate QED and isospin corrections to the (fictitious) η(s)-meson mass, which is used to tune s-quark masses in lattice simulations.
HPQCD Collaboration, "New high-precision b, c, and s masses from pseudoscalar-pseudoscalar correlators in nf = 4 lattice QCD" arXiv:2508.02862 (August 4, 2025).