CDF and D0 were well represented by two students today, Per and Zeynep, who presented their measurements of the top quark charge. The standard model top must have charge 2/3, but a simple extension (adding a fourth quark generation) would give an exotic quark with mass 175 GeV, pushing the SM top quark up to over 200 GeV. It would have 4/3 charge. Clearly, if we want to call a top a top, we need to measure its charge.
Per and Zeynep showed that the quark we call “top” is, indeed, very standard model-like in its charge. Impressive work, and another triumph for the standard model.
