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arXiv · 2212.02366

The hadronic running of the electromagnetic coupling and electroweak mixing angle

Teseo San José·Hartmut Wittig·Marco Cè·Antoine Gérardin·Georg von Hippel·Harvey B. Meyer·Kohtaroh Miura·Konstantin Ottnad·Andreas Risch·Jonas Wilhelm
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Abstract

We present results for the hadronic running of the electromagnetic coupling and the weak mixing angle from simulations of lattice QCD with $N_f=2+1$ flavours of $O(a)$-improved Wilson fermions. Using two different discretisations of the vector current, we compute the quark-connected and -disconnected contributions to the hadronic vacuum polarisation (HVP) functions $\barΠ^{γγ}$ and $\barΠ^{Zγ}$ for spacelike squared momenta $Q^2\leq 7$ $\mathrm{GeV}^2$. Our results are extrapolated to the physical point using ensembles at four lattice spacings, with pion masses ranging from 130 to 420 MeV. We observe a tension of up to 3.5 standard deviations between our lattice results for $Δα_{\rm had}^{(5)}(-Q^2)$ and estimates based on the $\textit{R}$-ratio for space-like momenta in the range $Q^2=3-7\,\rm GeV^2$. To obtain an estimate for $Δα_\mathrm{had}^{(5)}(M_Z^2)$, we employ the Euclidean split technique. The implications for comparison with global electroweak fits are assessed.

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Teseo San José, Hartmut Wittig, Marco Cè, Antoine Gérardin, Georg von Hippel, Harvey B. Meyer, Kohtaroh Miura, Konstantin Ottnad, Andreas Risch, Jonas Wilhelm. 2022-12-05. The hadronic running of the electromagnetic coupling and electroweak mixing angle. https://arxiv.org/abs/2212.02366

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