Invited Seminars

IIHE invited seminar: Precision Measurement of the Strong Coupling Constant with Z Boson Kinematics (Prof. Dr. Matthias Schott)


The strong coupling constant, alphaS, is one of the fundamental parameters of the Standard Model (SM) of particle physics and describes the strength of the strong interaction. It determines how strongly quarks and gluons as building blocks of protons and neutrons interact with each other. More concretely, alphaS, is one of the three coupling constants within the SM and therefore plays a fundamental role in our ability to describe the universe. The precision measurement of alphaS, is notorious difficult and most experimental measurements yield relative uncertainties of several percent. In recent years, we developed a fundamentally new approach to measure the strong coupling constant using the kinematic properties of Z bosons produced in proton-proton collisions, yielding a relative uncertainty of 0.8% and being the most precise measurement to date. Our approach of this measurement lies in the study of the Z boson kinematics in proton-proton collisions. Using the Z boson for this purpose provides three huge advantages: First of all, its kinematics in proton-proton collisions show a significant dependence on the strong coupling constant; secondly, the kinematics can be precisely predicted and thirdly, once the Z boson is created and decayed in electrons or muons, it does not experience any further effects from the strong interaction. In this talk, we summarize the basic concepts of this measurement.

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Organized by

Steven Lowette