College Park, Maryland      June 6 - 10 , 2004

M4-B5 (5:00 PM): Review of fundamental physics with ultracold neutrons (Invited)

S. N. Dzhosyuk (Harvard University)

Ultracold neutrons (UCN), typically with energies of order 10-7 eV, allow for both long observation times and long interaction times with materials, thus making UCN a valuable tool for testing fundamental physics theories and symmetries. Several experiments using UCN aim to improve a precision of the measurement of the neutron lifetime and the neutron beta decay asymmetry coefficient "A". When combined, these parameters will help clarify present discrepancies in our understanding of the weak interaction. Another experiment, a measurement of the neutron electric dipole moment (EDM) using UCN in liquid helium, aims to improve the experimental limits by two orders of magnitude. This sensitivity will allow tests of models such as supersymmetry in the continuing quest to observe CP violation beyond the Standard Model, that is necessary to explain the cosmological baryon asymmetry. Several new UCN sources are being built in the U.S. and abroad. The higher densities of UCN that will soon be available will dramatically improve the precision of these measurements and open up the possibilities for additional condensed matter studies at low Q2. A review of the current status of the above-mentioned experiments and new facilities for UCN production will be presented.

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