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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Probing Time-reversal Invariance with Atoms and Neutrons
Date: Thursday, May 17th
Time: 2:30 pm - 3:30 pm
Place: 4274 Chamberlin
Speaker: Tim Chupp, University of Michigan
Abstract: Time reversal is not a perfect symmetry of nature as evidenced by decays of K and B mesons. This means that physical processes and even the properties of atoms and elementary particles would change with the reversal of time. Assuming charge-conjugation-parity (CPT) invariance, T- invariance implies CP invariance, an essential element of baryogenesis, the generation of more matter, compared to antimatter, in the early universe. CP-invariance violation has been observed in the decays of K and B mesons, and is incorporated into the Standard Model of particle physics, but it it not sufficient to produced the observed baryon asymmetry. So we search on for new manifestations of CP or T invariance violation. Observing a permanent electric dipole moment of an atom or the neutron (sometimes called the Z=0 atom) would be direct evidence of T violation and would set the scale for new physics that could generate the baryon asymmetry. T-violating observables in neutron decay include the correlations of neutron spin with the proton and electron momentum. I will discuss EDM experiments using rare isotopes as well as neutron experiments including the recently complete emiT-II experiment.
Host: Michael Ramsey-Musolf
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