Elizabeth Simmons

Elizabeth Simmons

Ph.D., Harvard University (1990)


Office: MHA 5601
Phone: (858) 534-3130

Research Statement

The Standard Model of particle physics is consistent with data gathered at energies accessible to current experiments, but cannot explain phenomena at the higher energies characteristic of earlier eras in our universe. Therefore, physics beyond the Standard Model must exist.

I study how new physics impacts the masses of the elementary particles, especially the heaviest matter particle, the top quark. My work focuses on identifying where data anomalies hint at new symmetry structures, developing testable theories, proposing fresh tests of existing models, and finding novel ways to extract meaning from data.

In [a] I showed that many new-physics models could not explain the top quark’s large mass without incurring side effects forbidden by the data. This channeled model-building toward theories with “custodial” symmetry structures mitigating such issues [b, c, d, e].

I also found that the top quark could play a special role in the origin of all particle masses. Extending the symmetry structure of the Standard Model to include new weak- or strong-nuclear properties for the top quark allows top-quark bound states [f, g, h] or “top partner” states [h, i] to drive the “flavor symmetry breaking” that gives different masses to otherwise similar matter particles. It also offers the top quark a role in the “electroweak symmetry breaking” process that separates electromagnetism from the weak-nuclear force and makes the very existence of mass possible [b, j].

My work has also demonstrated the impacts of expanding the strong-force symmetries of the Standard model [k, l]. I delineated the properties of new heavy “coloron” resonances present in these extended theories, including how they are constrained by existing data and how they can manifest in future experiments [m, n, o, p]. Recently, I proposed [q, r, s] new ways of analyzing high-energy collider data to reveal the symmetry properties of such resonances upon discovery.