![]() ![]() New data from the ATLAS experiment shows, with unprecedented precision, the production of W and Z bosons through the weak interaction. But the low x sea-quark composition – expressed in terms of the lighter quarks named up, down and strange quarks – is still not well understood. ![]() Where this fraction is below 0.01, the proton constituents are mainly gluons and a sea of quark-antiquark pairs.Įlectron-proton scattering data from the HERA collider has constrained the gluon and the sum of all quarks weighted by the square of their electric charge. At the LHC, reactions involve quarks or gluons that carry a certain fraction (x) of the proton’s momentum. Much has since been learned through a combination of new experimental data and theoretical advances. Soon after QCD was born and the existence of gluons inside the proton was established. The discovery of quarks as the elements of the “partonic” structure of the proton dates about 50 years. These determine the dynamic substructure of the proton. Abstract We report a new determination of the strange quark contribution to the protons magnetic form factor at a four-momentum transfer Q 2 0.1 (GeV/ c ). Instead, QCD can connect measurements made in different processes and at different energy scales such that universal properties (“parton density functions” (PDFs)) can be extracted. But, the theory of the strong interactions – quantum chromodynamics (QCD) – does not allow physicists to calculate the composition of protons from first principles. The protons collided by the LHC are not elementary particles, but are instead made up of quarks, antiquarks and gluons. New precision measurements of the W and Z boson cross sections show the proton contains more strange quarks than previously believed. ![]()
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January 2023
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