Recent Results from Jade on Electroweak Interactions

Abstract

The Jade collaboration¹ has performed measurements at Petra at an average center-of-mass (cms) energy of W ∼ 35 GeV in order to test Quantum Electrodynamics (QED) and electroweak theories. QED tests are still possible because the influence of the neutral weak current is negligible in many places, e.g. in e⁺e^- → γγ, or in the total cross sections for e⁺e^- → e⁺e^-, γγ, μ⁺μ^-, and τ⁺τ^-. On the other hand the interference of the electromagnetic and the weak amplitudes leads to an asymmetry in the angular distributions of μ⁺μ^- and τ⁺τ^-, which was established for the first time at Petra. The measurements can be compared to predictions of electroweak theories, in particular the “standard model” of Glashow, Salam, and Weinberg², which has successfully described neutral current phenomena in neutrino scattering³ and polarized e-d scattering⁴. The tests at Petra were performed at a Q2 much higher than previously available.