PoS - Proceedings of Science
Volume 430 - The 39th International Symposium on Lattice Field Theory (LATTICE2022) - QCD in searches for physics beyond the Standard Model
The muon anomalous magnetic moment: is the lattice spacing small enough?
T. Blum, M. Golterman* and S. Peris
Full text: pdf
Pre-published on: January 31, 2023
Published on: April 06, 2023
We present new results for the light-quark connected part of the leading order
hadronic-vacuum-polarization (HVP) contribution to the muon anomalous magnetic moment,
using $2+1+1$ staggered fermions. We have collected more statistics on previous ensembles, and
we added two new ensembles. This allows us to reduce statistical errors on the HVP
contribution and related window quantities significantly. We also calculated the
current-current correlator to next-to-next-to-leading order (NNLO) in staggered chiral
perturbation theory, so that we can correct to NNLO for finite-volume, pion-mass
mistuning and taste-breaking effects. We discuss the applicability of NNLO chiral
perturbation theory, emphasizing that it provides a systematic EFT approach to the HVP
contribution, but not to short- or intermediate-distance window quantities. This makes
it difficult to assess systematic errors on the standard intermediate-distance window
quantity that is now widely considered in the literature. In view of this, we
investigate a longer-distance window, for which EFT methods should be more reliable.
Our most important conclusion is that new high-statistics computations at lattice
spacings significantly smaller than 0.06 fm are indispensable. The ensembles we use
have been generously provided by MILC and CalLat.
DOI: https://doi.org/10.22323/1.430.0300
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