SEMINAIRE MERCREDI 4 (Wednesday) 14h (amphi 5 du CPT!! attention, jour,
heure et lieu inhabituels!!Séminaire commun CPT/CPPM)
Marseille-Luminy

Aron Bernstein
MIT

Title: Measurement of the pi0 Lifetime: Probing the QCD Axial Anomaly

Abstract: The pi0 lifetime has been measured with significantly improved
accuracy at Jefferson Lab using the Primakoff effect. This was achieved
by careful control of all of the experimental parameters and included
auxiliary measurements of the Compton effect and pair production. This
measurement is a test of a prediction based on the QCD axial anomaly
plus few percent chiral corrections which are proportional to the mass
difference of the up and down quarks. The basic physics, and a
comparison of theory and experiment, will be presented in the context
of spontaneous chiral symmetry breaking in QCD, some of its physical
consequences, and other experimental tests.