Vacuum correlators at short distances from lattice QCD

Journal of High Energy Physics

Harvey B. Meyer¹  Arianna Toniato²  Csaba Török²  Tim Harris³  Marco Cè⁴ 

[1] Helmholtz Institut Mainz, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany;GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany;PRISMA+ Cluster of Excellence & Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany;PRISMA+ Cluster of Excellence & Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany;School of Physics and Astronomy, University of Edinburgh, EH9 3JZ, Edinburgh, U.K.;Theoretical Physics Department, CERN, CH-1211, 23, Geneva, Switzerland;

关键词: Lattice QCD;    Perturbative QCD;   

DOI  :  10.1007/JHEP12(2021)215

来源: Springer

【 摘 要 】

Non-perturbatively computing the hadronic vacuum polarization at large photon virtualities and making contact with perturbation theory enables a precision determination of the electromagnetic coupling at the Z pole, which enters global electroweak fits. In order to achieve this goal ab initio using lattice QCD, one faces the challenge that, at the short distances which dominate the observable, discretization errors are hard to control. Here we address challenges of this type with the help of static screening correlators in the high-temperature phase of QCD, yet without incurring any bias. The idea is motivated by the observations that (a) the cost of high-temperature simulations is typically much lower than their vacuum counterpart, and (b) at distances x3 far below the inverse temperature 1/T, the operator-product expansion guarantees the thermal correlator of two local currents to deviate from the vacuum correlator by a relative amount that is power-suppressed in (x3T). The method is first investigated in lattice perturbation theory, where we point out the appearance of an O(a2 log(1/a)) lattice artifact in the vacuum polarization with a prefactor that we calculate. It is then applied to non-perturbative lattice QCD data with two dynamical flavors of quarks. Our lattice spacings range down to 0.049 fm for the vacuum simulations and down to 0.033 fm for the simulations performed at a temperature of 250 MeV.

【 授权许可】

CC BY