2005/12/15 by Thomas Becher, Matthias Neubert
Mathematics · Physics and Astronomy · #Combinatorics #Dimension (graph theory) #Function (biology) #High-Energy Particle Collisions Research #Jet (fluid) #Mathematical physics #Mathematics #Order (exchange) #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Scale (ratio) #hep-ph
paper · pdf · doi:10.1016/j.physletb.2006.01.006
published as Phys.Lett.B633:739-747,2006 · 13 pages, 2 figures
arxiv created 2005/12/15 · openalex publication_date 2006/01/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A theoretical analysis of the partial inclusive B ¯ → X s γ decay rate with a cut E γ ⩾ E 0 on photon energy must deal with short-distance contributions associated with three different mass scales: the hard scale m b , an intermediate scale m b Δ , and a soft scale Δ , where Δ = m b − 2 E 0 ≈ 1 GeV for E 0 ≈ 1.8 GeV . The cut-dependent effects are described in terms of two perturbative objects called the jet function and the soft function, which for a next-to-next-to-leading order analysis of the decay rate are required with two-loop accuracy. The two-loop calculation of the soft function is presented here, while that of the jet function will be described in a subsequent paper. As a by-product, we rederive the two-loop anomalous-dimension kernel of the B -meson shape-function.