High Energy Theory Seminar

QCD remains intractable in the high-energy soft regime, where all standard methods break down. This regime governs total hadronic cross-sections, which have long been observed to grow with energy, a phenomenon that is still very poorly understood. A basic expectation is that the proton eventually becomes a slowly expanding "black disk" that absorbs everything within an effective radius, though whether this is compatible with the basic axioms of QFT remains unclear. Another expectation is that this universal growth is driven by the Pomeron, a Regge trajectory whose spectrum of particles has never been rigorously determined. The main established result is the Froissart bound on the total cross-section, but its asymptotic nature prevents any meaningful comparison with data. In this talk I will argue that the modern nonperturbative S-matrix bootstrap provides a systematic way to revisit these questions. I will derive a finite-energy bound on the total cross-section, improving on the Froissart bound, and present the strongest interacting amplitude that the bootstrap outputs. I will compare these results with proton–proton experimental data.

The talk is in 469 Lauritsen.

Contact [email protected] for Zoom information.