Particle/antiparticle symmetry confirmed with ultra-high precision

By comparing the revolution frequencies of antiprotons and negatively charged hydrogen ions in a strong magnetic field, the to date most precise mass comparison could be performed and thus the most precise direct test of the matter/antimatter symmetry with baryons, particles consisting of each three quarks. The result: the charge-to-mass ratios of protons and antiprotons are identical to the eleventh digit.