6533b7d1fe1ef96bd125ca85

RESEARCH PRODUCT

Determination of m¯b/m¯c and m¯b from nf=4 lattice QCD+QED

subject

description

We extend HPQCD's earlier ${n}_{f}=2+1+1$ lattice-QCD analysis of the ratio of $\overline{\mathrm{MS}}$ masses of the $b$ and $c$ quark to include results from finer lattices (down to 0.03 fm) and a new calculation of QED contributions to the mass ratio. We find that ${\overline{m}}_{b}(\ensuremath{\mu})/{\overline{m}}_{c}(\ensuremath{\mu})=4.586(12)$ at renormalization scale $\ensuremath{\mu}=3\text{ }\text{ }\mathrm{GeV}$. This result is nonperturbative. Combining it with HPQCD's recent lattice $\mathrm{QCD}+\mathrm{QED}$ determination of ${\overline{m}}_{c}(3\text{ }\text{ }\mathrm{GeV})$ gives a new value for the $b$-quark mass: ${\overline{m}}_{b}(3\text{ }\text{ }\mathrm{GeV})=4.513(26)\text{ }\text{ }\mathrm{GeV}$. The $b$-mass corresponds to ${\overline{m}}_{b}({\overline{m}}_{b},{n}_{f}=5)=4.202(21)\text{ }\text{ }\mathrm{GeV}$. These results are the first based on simulations that include QED.