Deep Inelastic Scattering at Large Energy and Momentum Transfers: Recent Results from HERA

TL;DR

This paper reviews recent results from HERA on deep inelastic scattering, highlighting measurements of proton structure, tests of the Standard Model, and searches for new physics phenomena at very small scales.

Contribution

It provides updated experimental data on proton structure functions and tests the Standard Model at unprecedented energy scales, including searches for new physics beyond current theories.

Findings

Evidence of weak contributions in neutral current interactions.

Confirmation of electroweak unification at high Q^2.

No signs of instantons, compositeness, or extra dimensions found.

Abstract

Data from H1 and ZEUS on the structure and the quark and gluon densities of the proton are discussed. A brief excursion is made into the field of inclusive diffraction by deep inelastic scattering. The comparison of e- p and e+ p scattering at large momentum transfers demonstrates clearly the presence of weak contributions in neutral current interactions. The comparison with the corresponding charged current results shows at Q2 values above the masses squared of the heavy vector bosons the unification of electromagnetic and weak interactions. The new data are testing the validity of the Standard Model down to spatial resolutions of the order of 10^{-16} cm. Intensive searches have been performed for a manifestation of instantons, for signs of compositeness of quarks and leptons and for the effect of extra dimensions.