James Glanz
Minneapolis--It was only last year that particle physicists confirmed the existence of the top quark, the heaviest building block of matter. Now they are seeing top quarks by the scores and getting an accurate fix on their mass, physicists reported here at a meeting of the American Physical Society's division of particle and fields. The refined top mass is providing a guidepost to a bigger prize: the still-unseen Higgs boson, a particle that would help explain the array of different masses seen in other elementary particles, one of the major unsolved mysteries of particle physics.