The MUonE experiment: mu-e elastic scattering as a key to understand the muon g-2 puzzle

The MUonE experiment aims to measure the differential cross section of the μ \ e elastic scattering using the CERN SPS muon beam with mean energy of 160 GeV onto atomic electrons of a low-Z target. Thanks to the intense M2 beam with in-spill intensity of 5×10⁷ muons/s, a precise measurement of the scattering angles allows to extract the running QED coupling, and by a novel approach the leading hadronic contribution to the muon anomalous magnetic moment. This determination will be completely independent from the usual data-driven method, based on measurements of the R-ratio in e⁺e⁻ annihilations, and could clarify the discrepancy between these results and the theory-based estimates from recent lattice QCD calculations. The MUonE challenge resides in the control of theoretical and experimental uncertainties to an unprecedented level of precision for a scattering experiment. A pilot run was held this summer, operating for the first time two tracking stations and a prototype electromagnetic calorimeter connected to a triggerless readout system. The status and plans of the experiment will be presented.