Friday, December 12, 2003, 16:00
WHGA Auditorium
Dr. H. Abele, Univ. Heidelberg
Abstract:
This talk is about the relationship between the observables in neutron
beta-decay and the accepted modern theory of particle physics known as
the Standard Model. We try to shed light on the following topics: the
coupling strength of charged weak currents, the universality of the
electroweak interaction, quark-mixing, and the origin of parity
violation. We report on measurements of the angular correlation
coefficients A and B in the decay of polarized neutrons. Coefficient A
and the neutron lifetime give the first element of the quark-mixing CKM
matrix V_ud. With this value, we find a deviation from the Standard
Model of particle physics, 3 times the stated error. With our ongoing
experiments at the ILL in Grenoble, a possible deviation from the
Standard Model will be seen in the raw data without correction. The
coefficient B has been measured with a new technique making use of an
electron detector and a proton detector in the same hemisphere. This
coefficient is a measure of the antineutrino asymmetry and its value is
sensitive to an admixture of right handed currents in the weak
interaction.