High Energy Physics Seminar

Hadronic physics is notoriously challenging to study due to the non-perturbative nature of QCD. Although significant advances have been made in recent years, there are still no reliable methods for calculating observables in multibody hadron decays. As a result, flavor physics predictions, which rely on the approximate SU(3) flavor symmetry of QCD, remain the state of the art in many cases. While flavor symmetries cannot predict hadronic matrix elements, they yield relations among them, called flavor sum rules, which can be tested experimentally.

In this talk, I will focus on U-spin, an SU(2) subgroup of SU(3) flavor symmetry relating d and s quarks. I will present our results that reveal a rich mathematical structure underlying the sum rules. Understanding this structure allows us to formulate an algorithm for deriving all U-spin amplitude sum rules to any order in symmetry breaking and for an arbitrary system of hadron decays related by U-spin. This novel approach requires no explicit calculations and admits a simple diagrammatic interpretation. I will argue that, despite a relatively large breaking of order 30%, a systematic expansion in U-spin breaking can be used for precision physics.

The talk is in 469 Lauritsen.

Contact theoryinfo@caltech.edu for Zoom link.