Abstract
The quark-line disconnected diagram is a potentially important ingredient in lattice QCD calculations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. It is also a notoriously difficult one to evaluate. Here, for the first time, we give an estimate of this contribution based on lattice QCD results that have a statistically significant signal, albeit at one value of the lattice spacing and an unphysically heavy value of the $u/d$ quark mass. We use HPQCD's method of determining the anomalous magnetic moment by reconstructing the Adler function from time-moments of the current-current correlator at zero spatial momentum. Our results lead to a total (including $u$, $d$ and $s$ quarks) quark-line disconnected contribution to $a_{\mu}$ of $-0.15\%$ of the $u/d$ hadronic vacuum polarization contribution with an uncertainty which is 1\% of that contribution.
Highlights
The high accuracy with which the magnetic moment of the muon can be determined in experiment makes it a very useful quantity in the search for new physics beyond the Standard Model
The s quark mass is tuned to be close to its physical value using the combination of meson masses 2m2K − m2π fixing the lattice spacing from the mass of the Ω baryon
The gluon field ensemble used here for the Hadron Spectrum results has a spatial lattice spacing of around 0.12 fm, based on an anisotropy of 3.444 [26]. This corresponds to the “coarse” lattice spacing in the MILC gluon field ensembles used by the HPQCD collaboration [9]
Summary
This contribution, which we denote aμ;HVP, is currently determined most accurately from experimental results on eþe− → hadrons or from τ decay to be of order 700 × 10−10 with a 1% uncertainty or better [3,4,6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
