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The origin of the baryon asymmetry in the Universe
remains one of the biggest mysteries in contemporary physics.
Measurements in the B and K systems have definitively demonstrated CP
violation of the type allowed within the Standard Model, but this CP
violation is orders of magnitude too small to explain the baryon
asymmetry. The neutron electric dipole moment (nEDM) is a CP-violating
observable with the useful property that its contribution from SM
processes is extremely small, however CP violation in models beyond the
Standard Model almost invariably produces much larger contributions to
the nEDM. Thus the nEDM is a sensitive probe of models of CP violation,
and failure to observe an nEDM has given rise to both the strong and the
supersymmetric CP problems. Measuring the nEDM is a tremendous
experimental challenge, which requires simultaneous use of extremely
high voltage, very precisely controlled magnetic fields, and an intense
source of polarized ultra-cold neutrons (neutrons of such low energy
that they can be stored in a bottle like milk, controlled with water
valves, and outrun or rather outwalked by the experimenters). The
seminar will report on the experiment at the ILL research reactor in
Grenoble, France, which just announced the world's most sensitive
measurement of the nEDM, and also about efforts there to build an
entirely new type of experiment which will be two orders of magnitude
more sensitive.
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