Abstract
We extend HPQCD's earlier $n_f=4$ lattice-QCD analysis of the ratio of $\overline{\mathrm{MSB}}$ masses of the $b$ and $c$ quark to include results from finer lattices (down to 0.03fm) and a new calculation of QED contributions to the mass ratio. We find that $\overline{m}_b(\mu)/\overline{m}_c(\mu)=4.586(12)$ at renormalization scale $\mu=3$\,GeV. This result is nonperturbative. Combining it with HPQCD's recent lattice QCD$+$QED determination of $\overline{m}_c(3\mathrm{GeV})$ gives a new value for the $b$-quark mass: $\overline{m}_b(3\mathrm{GeV}) = 4.513(26)$GeV. The $b$-mass corresponds to $\overline{m}_b(\overline{m}_b, n_f=5) = 4.202(21)$GeV. These results are the first based on simulations that include QED.
Highlights
Accurate masses for heavy quarks are important for QCD-phenomenology generally, but they will be important for high-precision searches for new physics in Higgs decays [1]
In this paper we described a new calculation of the ratio of the MS masses of the b and c quarks, mbð3 mcð3
Where nf is the number of quark flavors in the sea. This is the first calculation of the mass ratio based on simulations that include QED, and it makes no use of weak-coupling perturbation theory
Summary
Accurate masses for heavy quarks are important for QCD-phenomenology generally, but they will be important for high-precision searches for new physics in Higgs decays [1]. In this paper we present a new result for the ratio mb=mc of the MS masses of the b and c quarks. The ratio can be combined with recent accurate determinations of the c-quark mass to obtain new results for the b-quark mass. Lattice simulations of b quarks are complicated by the quark’s large mass, which leads to large lattice-spacing errors when the b quarks are described by the Dirac equation (as opposed to, say, NRQCD [2]). And in our earlier paper we use the quenched QED approximation, which omits contributions from photons coupling to sea quarks.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
