Northwestern University

Tue 2:00 PM

CFP Colloquium: Holger Müller: Measurement of the fine-structure constant as test of the Standard Model

When: Tuesday, May 21, 2019
2:00 PM - 3:15 PM  

Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students

Contact: Laura Nevins   847.467.6678

Group: Center for Fundamental Physics Colloquia

Category: Lectures & Meetings


Abstract: Measurements of the fine-structure constant are powerful tests of the consistency of theory and experiment across physics. We have used the recoil frequency of cesium-133 atoms in an atom interferometer to measure h/M, the ratio of the Planck constant and the mass of the atom, from which we derive the most accurate measurement of the fine-structure constant to date: α = 1/137.035999046(27). To reach this accuracy, we have used multiphoton interactions (Bragg diffraction and Bloch oscillations) to increase the phase shift in the interferometer, and to control systematic effects. The measurement is sensitive to interesting physics, both within the Standard Model and beyond. By combining it with Standard-Model theory, we can predict the anomaly of the magnetic moment of the electron. Comparison between theory and experiment confronts a number of Standard-Model predictions with experiment, some of them for the first time. These include the fifth-order influence of QED, the influence of virtual muons, as well as hadronic effects. The measurement also enables a search for physics beyond the standard model, including scalar particles and vector bosons.

Associate Professor Holger Müller, University of California, Berkeley

Host: CFP

Keywords: Physics, Center for Fundamental Physics

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