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Tabletop Particle Physics: Precision Measurements Aid the Search for New Particles

by Catherine Meyers


Mention particle physics, and many people think of enormous atom smashing machines like the Large Hadron Collider, whose 27 kilometers of track lie buried under the Swiss-French border and cost billions of dollars to build. In the Thursday morning talk “Tabletop Probes for TeV Physics,” visionary speaker David DeMille of Yale University encouraged a different perspective.


DeMille described tabletop experiments that can probe for new particles at energy scales even higher than the LHC. The trick lies in measuring the properties of ordinary particles like the electron with extreme precision.


As electrons move through space, they interact with other particles that pop into and out of existence -- interactions that should cause the electron to have an uneven distribution of charge, a property known as an electric dipole moment, or EDM.


According to the Standard Model of particle physics, the electron’s EDM should be too small to measure with current techniques. However, the Standard Model fails to explain such physics mysteries as the existence of dark matter or the preponderance of matter over antimatter, so physicists know it is incomplete. Newer theories often posit the existence of new, heavy particles that would result in a larger electron EDM.


In recent years DeMille and his group have conducted a series of experiments to measure the electron’s electric dipole moment. So far, they have not detected it, but their experiments and others like it have placed increasingly precise limits on how big the EDM could be. New technology such as optical lattices that can trap molecules should enable researchers to tighten these constraints even further, he said.


“The lack of EDM is putting pressure on theories such as supersymmetry,” DeMille said, which is a reason to keep pushing for better measurements. “Either we’ll find something, or much of what particle physicists have been expecting for the last 30 years may be completely wrong.”

Posted: 21 Sep 2018 by Catherine Meyers

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