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Physics Colloquium: "Small-Scale Physics Tests of the Standard Model, Its Symmetries and Its Proposed Fixes"

Event Type
Department of Physics
141 Loomis
Sep 13, 2017   4:00 pm  
Gerry Gabrielse, Harvard University/Northwestern University
Stephanie Johansson
Originating Calendar
Physics - Colloquium

Despite this great triumph, the Standard Model is also a great frustration of modern physics. It cannot explain why a universe made of matter survived the big bang, nor can it explain dark matter or dark energy. A number of adjustments to the Standard Model have been proposed. Small-scale physics measurements have an important role in testing the Standard Model, its symmetries and proposed fixes.

For example, the electron's magnetic and electric dipole moments provide some of the most stringent tests of the Standard Model of particle physics and proposed "improvements" to this description. The most precise prediction of the Standard Model is the value of the electron's magnetic dipole. Our experimental determination of this moment to 3 parts in 10^{13} -- the most precise determination of an elementary particle property -- shows that the prediction is correct to at least 12 significant figures. A positron measurement is now underway to test the fundamental symmetry of the Standard Model, and antihydrogen experiments are getting closer to making significant tests.

To test proposed fixes to the Standard Model, our ACME collaboration recently completed a 12 times more sensitive measurement of the electron's electric dipole moment, and substantial improvements are planned. The Standard Model predicts a moment too small to measure, while proposed adjustments (e.g. supersymmetric models) generally cannot avoid predicting an electric dipole moment that could be within range of our measurement sensitivity.  

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