Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 22: Plenarsitzung
HK 22.2: Plenarvortrag
Mittwoch, 19. März 2003, 09:00–09:30, P
Neutron β-decay and the Standard Model — •Hartmut Abele — Physikalisches Institut, Philosophenweg 12, 69120 Heidelberg
This talk is about the interplay between neutron physics, cosmology and the Standard Model of elementary particle physics. Neutrons test the very early stages of the universe with a variety of observables. New motivations for experiments come from frameworks where the fundamental Planck scale, the scale at 10−44 s after the big bang, is taken to the weak scale, the energy scale of the Standard Model at 10−10 s after the big bang. Furthermore, the quark-mixing CKM-matrix remains unexplained in the Standard Model as well as CP-violation, which might explain the baryon-antibaryon asymmetry of the universe.
We will discuss two aspects of neutron physics with cold and ultra-cold neutrons in detail. First, a recent gravity experiment demonstrates quantum states in the gravitational potential of the Earth with ultra-cold neutrons. A side-effect of this experiment is its sensitivity for gravity-like forces at length scales below 10 µm. In light of recent theoretical developments in higher dimensional field theory, gauge fields can mediate forces that are 106 to 108 times stronger than gravity at submillimeter distances, exactly in the interesting range. Second, measurements of various mixed American-British-French-German-Hungarian-Japan-Russian groups of researchers determine the strength of the weak interaction of the neutron, which gives us unique information on the question of quark mixing. Neutron β-decay experiments now challenge the Standard Model of elementary particle physics with a deviation, which is 3.0 times the stated error.