αs 2002

Compatibility of αs(Mτ) with αs(MZ)

αS: from DIS to LEP ∗

The strong coupling αS is a fundamental parameter of the Standard Model. In comparison to parameters like αem, MZ and sin 2 θW it is relatively poorly known. However the precision of αS measurements has improved dramatically in recent years. More than twenty different types of process, from lattice QCD studies to the highest energy colliders, can be used to measure αS accurately. The most preci...

αs(MZ) from the Hidden Sector

By including the effects of superstring thresholds, we reconsider minimal string unification together with the requirement of producing a supersymmetry-breaking gluino condensate in the hidden sector. This gives, for examples of phenomenologically-viable Z ′ 8 and other related orbifolds, the constraint that 0.1215 ≤ αs(MZ) ≤ 0.1270. In such models, a hidden photino can be a source of cosmologi...

The Determination of αS at Hadron Colliders

Hadron colliders offer a unique opportunity to test perturbative QCD because, rather than producing events at a specific beam energy, the dynamics of the hard scattering is probed simultaneously at a wide range of momentum transfers. This makes the determination of αS and the parton density functions (PDF) at hadron colliders particularly interesting. In this paper we restrict ourselves to extr...

Jet-Studies and αs-determinations at HERA ∗.

Recent results from the H1 and ZEUS Collaborations on inclusive single and multiple jet production in the neutral current deep inelastic scattering of electrons/positrons on protons and the high energy photoproduction on protons at HERA are reported. The results are compared with NLO QCD calculations and have been used to determine the strong interaction coupling constant αs.