Do top quarks consult the constellations?

A sidereal day is the time it takes the Earth to rotate back to the same alignment with respect to distant stars.

A premise of Einstein’s theory of Special Relativity, and a fundamental part of the Standard Model, is that the laws of physics are the same for everyone regardless of where they are and which way they are facing. If this were not true, the results of an experiment would depend on how the apparatus is oriented with respect to the rest of the universe. The sidereal position, or the orientation with respect to the constellations, of an experiment would influence its results. Experiments performed on the surface of the Earth would yield different results at different sidereal hours due to the rotation of the Earth.

The Standard Model does not include gravity. Some theories that aim to unify the Standard Model with gravity allow for orientation-dependent differences in the behavior of particles. The Standard-Model Extension effective field theory allows experimentalists to test for this behavior in a general way. It permits each particle to have a different level of dependence on sidereal time. While such daily time dependence has been ruled out for many particles in the Standard Model, only high-energy particle colliders like the Tevatron afford physicists the opportunity to directly test the top quark.

A recent analysis at DZero looked for sidereal time dependence in the production of top quark pairs. Seven years’ worth of top quark pair candidate data events were translated into sidereal time. Analyzers then looked for daily sidereal time dependence in the production rate of top quark pairs. The DZero data was found to be consistent with no time dependence and sets the first limits on the possible size of sidereal time dependence on the behavior of the top quark.

—Mike Cooke

These physicists made major contributions to this analysis.

These physicists are the main administrators for the DZero Linux cluster, a crucial component of the DZero computing infrastructure that facilitates data analysis.