After 15 years of measurement and another eight years of scrutinizing and calculation, the particle physics collaborations H1 and ZEUS have published the most precise results about the innermost structure and behaviour of the proton. The two experiments which took data at DESY´s particle accelerator HERA from 1992 to 2007 have combined their data of over a billion collisions of protons with electrons or positrons, antiparticles of the electrons. About 300 authors of 70 institutions have contributed to the analysis.
“This publication is the culmination of HERA´s scientific programme and will be the most precise picture of the proton for a long time,” says DESY research director Joachim Mnich. “This legacy is not only important for the understanding of the very basic properties of matter but also an essential basis for experiments at proton colliders like the LHC at CERN in Geneva.”
Protons are in the core of each single atomic nucleus in the universe. Their composition of three quarks – two up and one down quark – which are held together by so-called gluons, carrier particles of the strong force, is well known since decades and taught in schools. However, the real picture of the proton is much more complicated: the proton is a sizzling soup where gluons can produce more gluons and can also split into pairs of quarks and antiquarks – the so-called sea quarks – all of them interacting again very quickly.