Department News

Jul 30, 2019 - OU physicists awarded European Physics Society prize

The CDF and DZero collaborations, the latter of which includes several current and former OU physicists, were awarded the 2019 High Energy and Particle Physics Prize from the European Physical Society for "the discovery of the top quark and the detailed measurement of its properties."  This prestigious prize is awarded every two years for outstanding contributions to the field.  OU made substantial contributions to the DZero experiment, without which the discovery would not have been possible.  Faculty members Brad Abbott, Phillip Gutierrez, Patrick Skubic, and Michael Strauss oversaw the work of seven PhD students, six postdoctoral research associates, and a research scientist (Horst Severini) on the DZero experiment.

The discovery of the top quark was announced jointly by the CDF and DZero collaborations in 1995.  At the time, the top quark was the only remaining matter particle predicted by the standard model yet to be observed.  Discovery was made challenging by the large mass of the top quark, which necessitated careful analysis of billions of high-energy proton-antiproton collisions produced by the Tevatron at Fermilab in Illinois.  The large mass of the top quark is also what makes it so fascinating; it is the heaviest of all known fundamental particles, with a mass at the electroweak scale.

In addition to discovering the top quark, the CDF and DZero experiments performed a number of important measurements of its properties.  The top quark mass was measured with a precision of 1%.  The cross section for production of a top-antitop pair was measured with a precision of 10%.  The production of a single top quark is much rarer, being mediated by the weak interaction.  However, the CDF and DZero collaborations also later observed this production mode, thanks in part to significant work from an OU postdoc (Supriya Jain)

The OU group continues to study top quark properties today, using collisions produced by the Large Hadron Collider at CERN.  Recently, Phillip Gutierrez and postdoc Muhammad Alhroob published the first 3-sigma evidence for the production of a single top quark in association with a Z boson, which is also mediated by the weak interaction.  Along with graduate student Dylan Frizzell, they are now finalizing a publication with incontrovertible >5-sigma observation of this process.

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