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We have performed the first $n_f = 2+1+1$ lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include $u/d$ quark masses going down to the physical point, tuning the $c$ quark mass from $M_{J/psi}$ and including the effect of the $c$ quarks electric charge through quenched QED. We obtain $M_{J/psi}-M_{eta_c}$ (connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on $M_{eta_c}$ of its decay to gluons, missing from the lattice calculation. This allows us to determine $Delta M_{eta_c}^{mathrm{annihiln}}$ =+7.3(1.2) MeV, giving its value for the first time. Our result of $f_{J/psi}=$ 0.4104(17) GeV, gives $Gamma(J/psi rightarrow e^+e^-)$=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the $c$ quark mass, including the impact of quenched QED to give $overline{m}_c(3,mathrm{GeV})$ = 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the $c$ quark HVP contribution to the anomalous magnetic moment of the muon. We obtain $a_{mu}^c = 14.638(47) times 10^{-10}$, which is 2.5$sigma$ higher than the value derived using moments extracted from some sets of experimental data on $R(e^+e^- rightarrow mathrm{hadrons})$. This value for $a_{mu}^c$ includes our determination of the effect of QED on this quantity, $delta a_{mu}^c = 0.0313(28) times 10^{-10}$.
We calculate the mass difference between the $Upsilon$ and $eta_b$ and the $Upsilon$ leptonic width from lattice QCD using the Highly Improved Staggered Quark formalism for the $b$ quark and including $u$, $d$, $s$ and $c$ quarks in the sea. We have
We determine the decay rate to leptons of the ground-state $Upsilon$ meson and its first radial excitation in lattice QCD for the first time. We use radiatively-improved NRQCD for the $b$ quarks and include $u$, $d$, $s$ and $c$ quarks in the sea wit
In calculations of the hyperfine splitting in charmonium, the contributions of the disconnected diagrams are considered small and are typically ignored. We aim to estimate nonperturbatively the size of the resulting correction, which may eventually b
We determine the mass of the charm quark ($m_c$) from lattice QCD with two flavors of dynamical quarks with a mass around the strange quark. We compare this to a determination in quenched QCD which has the same lattice spacing (0.1 fm). We investigat
We use lattice QCD simulations, with MILC gluon configurations and HISQ c-quark propagators, to make very precise determinations of moments of charm-quark pseudoscalar, vector and axial-vector correlators. These moments are combined with new four-loo