The MUonE experiment

Via Irnerio, 46 40126 Bologna, Italy

^* e-mail: umberto.marconi@bo.infn.it

Published online: 17 June 2019

Abstract

The precision measurement of the anomalous magnetic moment g − 2 of the muon at present exhibits a 3.5 σ deviation between theory and experiments. In the next few years it will be measured to higher precisions at Fermilab and J-PARC. The theoretical prediction can be improved by reducing the uncertainty on the leading hadronic correction $a_{\mu }^{HLO}$ to the g − 2. Here we present a new approach to determine $a_{\mu }^{HLO}$ with space-like data, by means of a precise measurement of the hadronic contribution to the effective electromagnetic coupling α, exploiting the elastic scattering of 150 GeV muons (currently available at CERN North area) on atomic electrons of a low-Z target. The direct measurement of $a_{\mu }^{HLO}$ in the space-like region will provide a new independent determination and will consolidate the theoretical prediction of the muon g − 2 in the Standard Model. It will allow therefore a firmer interpretation of the measurements of the future muon g − 2 experiments at Fermilab and J-PARC.