2023/09/15 by Guido Bell, Bell, Guido, Philipp Böer +7
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2309.08410
openalex publication_date 2023/09/15 · openalex created_date 2023/09/20 · openalex updated_date 2026/07/28
Using diagrammatic resummation techniques, we investigate the double-logarithmic series of the "soft-overlap" contribution to Bc → ηc transition form factors at large hadronic recoil, assuming the scale hierarchy mb ≫ mc ≫ Λ\rm QCD. In this case, the hadronic bound states can be treated in the non-relativistic approximation and the relevant hadronic matrix elements can be computed perturbatively. This setup defines one of the simplest examples to study the problem of endpoint singularities appearing in the factorization of exclusive B-decay amplitudes. We find that the leading double logarithms arise from a peculiar interplay of soft-quark "endpoint logarithms" from ladder diagrams with energy-ordered spectator-quark propagators, as well as standard Sudakov-type soft-gluon corrections. We elucidate the all-order systematics, and show that their resummation proceeds via a novel type of integral equations. The current status of the calculation, which includes all double logarithms in the Abelian limit, is reported.