Light-by-light scattering at next-to-leading order in QCD and QED

• DOI: 10.1016/j.physletb.2024.138555
• Publication Date: 2024-03-05T17:15:39Z
• Authors: Ajjath A H; Ekta Chaubey; Mathijs Fraaije; Valentin Hirschi; Hua-Sheng Shao
• Keywords: Unitarity; Massless particle; Helicity

The recent experimental observation of Light-by-Light (LbL) scattering at the Large Hadron Collider has revived interest in this fundamental process, and especially accurate prediction its cross-section, which we present here for first time Next-to-Leading Order (NLO) both QCD QED. We compare two radically different computational approaches, exact fermion mass dependence, thus offering a strong cross-check our results. approach is fully analytic method to calculate compact well-organized two-loop helicity amplitudes. second one entirely numerical leverages Local Unitarity construction. Our calculations agree with each other conclude that including contribution typically increases size NLO corrections. Moreover, find result converges slowly massless limit high-energy regime, emphasizing importance full dependence NLO. also results ATLAS measurement LbL ultra-peripheral lead-lead collisions, inclusion corrections reduces, but does not eliminate, existing tension theoretical predictions.