Avoided level crossing is a ubiquitous phenomenon across various fields, including high-energy physics, condensed matter physics, and quantum chemistry. In this talk, I will discuss level repulsion within the context of perturbative Quantum Chromodynamics (QCD) by studying the renormalization of light-ray operators. This study reveals an analytic operator spectrum (Chew-Frautschi plot) connecting two famous concepts in QCD: DGLAP (Dokshitzer–Gribov–Lipatov–Altarelli–Parisi) and BFKL (Balitsky-Fadin-Kuraev-Lipatov) physics, which provides a natural operator interpretation for previous insights from gauge/gravity duality and integrability. The renormalization problem is addressed through the analysis of soft and collinear dynamics in massless gauge theories, elucidating the intricate mixing structure between DGLAP and BFKL branches. I will also present how we can observe this effect from the Monte Carlo simulation data as well as CMS Open data, which provides a strong evidence for the level repulsion phenomenon in QCD dynamics.
Ankita Budhraja, Juraj Klaric, Johannes Michel, Maria Laura Piscopo