The New AMBER Experiment at the CERN SPS

The M2 beamline at CERN/SPS uniquely provides both muon and hadron beams of high intensity in the energy range of few hundred GeV. Its present versatility, together with the prospect of upgrading it with radio-frequency cavities to separate hadron species, make it the ideal location for an ambitious experimental program devoted to fundamental QCD measurements. AMBER is a new fixed-target experiment at CERN starting its data-taking in 2023. The proposed experimental studies address the various aspects of the so-called Emergence of Hadron Mass mechanism: the proton and mesons charge radii, the mesonic parton momentum distributions, the kaon polarizability and the kaon-induced hadron spectroscopy. The elastic muon-proton scattering process is proposed as a novel approach to the long-standing puzzle of the proton charge radius. Measurements of the antiproton production cross section in proton-helium collisions will provide much needed input for searches of Dark Matter. Pion- and kaon-induced Drell-Yan measurements will allow for an improved understanding of the meson structure, while the two beam charges provide sea-valence separation sensitivity. In the longer term, an upgrade of the M2 beamline may provide kaon beams of high purity by the radio-frequency separation technique. This would open new prospects in the strange-sector hadron spectroscopy and for the study of the kaon-induced Primakoff reaction.

Automated summary

The M2 beamline at CERN/SPS is a unique facility that provides high-intensity muon and hadron beams in the few hundred GeV energy range. AMBER is a new fixed-target experiment at CERN that aims to study fundamental aspects of QCD, focusing on the Emergence of Hadron Mass mechanism. The experiment will investigate various properties of protons and mesons, as well as explore the structure of mesons using pion- and kaon-induced Drell-Yan measurements. The upgrade of the M2 beamline with radio-frequency cavities may also enable high-purity kaon beams for further studies.