Speaker
Description
We discuss a method for calculating the heavy quark vacuum polarisation contribution to the muon anomalous magnetic moment, $a_\mu$, using perturbative QCD up to ${\cal O}\left(\alpha_s^3\right)$. This approach is independent of $e^+e^-$ cross-section data allowing a fully theoretical evaluation of these contributions. This method confirms an existing result at lower orders in $\alpha_s$ and we state a new explicit analytic formula which includes terms up to ${\cal O}\left(\alpha_s^3\right)$. Numerically the charm quark contribution to $a_\mu$ is found to be $a_\mu^c = (14.5 \pm 0.2)\times 10^{-10}$ and the bottom contribution is $a_\mu^b = (0.302 \pm 0.002) \times 10^{-10} $. Our uncertainty estimates include both parametric uncertainties, arising from $\hat{m}_q(\hat{m}_q)$ and $\alpha_s(\hat{m}_q)$, and theoretical uncertainties in the perturbative expansion. Comparison is then made between these results and those from alternative approaches such as, lattice QCD, or based on a dispersion relation and cross-section data.
| What is your topic? | Anomalous Magnetic Moment of the muon |
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