Friday, November 23, 2001, 16:00
Prof. O. Zimmer, TU München
Abstract:
Even after 50 years ongoing experimental effort, free neutron beta decay
has lost nothing of its fascination. The precise knowledge of the neutron
lifetime plays an important role in big bang nucleosynthesis of light
elements. Combined with the value of the neutron beta asymmetry, the weak
vector and axial-vector coupling constants of the neutron are determined
separately. Many semileptonic weak cross sections are derived from these
couplings. Including information about other weak decays one can test the
unitarity of the weak quark mixing matrix. Due to experimental access to
many angular correlations between spins and momenta of the particles
involved in neutron decay, several more precision tests of the standard
model of electroweak interaction are possible. These comprise tests for
scalar and tensor admixtures, searches for right-handed currents within
the frame of left-right symmetric models, as well as tests of time reversal
symmetry. The colloquium shall give a review of experimental research
in neutron beta decay, including recent developments and new projects.