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HK: Physik der Hadronen und Kerne

HK 53: Elektromagnetische und hadronische Proben VIII

HK 53.1: Group Report

Thursday, March 25, 1999, 14:00–14:30, E

New experimental results on neutron beta decay — •Oliver Zimmer — Institut Laue-Langevin, B. P. 156, F-38042 Grenoble Cedex 9

In the frame of the electroweak standard model of particle physics, neutron decay is described by only two parameters: the element V_ud of the weak quark mixing matrix (CKM matrix) and the ratio λ =g_A/g_V of the weak coupling constants of the neutron. Experimentally, a larger number of neutron decay parameters are accessible. These are the lifetime and various correlation coefficients between the spins and momenta of the particles involved in neutron decay. Hence, the problem is strongly overdetermined, and many tests going beyond the standard model are possible. These comprise searches for right handed currents within the frame of left-right symmetric models, tests of the unitarity of the CKM matrix, tests for tensor and scalar admixtures, as well as tests of time reversal symmetry. During the past years various groups working in this field have made considerable progress in neutron decay experimentation. In our presentation we shall give a survey on these new experiments and on the results concerning the standard model.