2002/02/28 by Ikaros Bigi, IKAROS BIGI, Nikolai Uraltsev +1 · 2 citations
Physics and Astronomy · #Neutrino Physics Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1142/s0217751x02010856
published as Int.J.Mod.Phys.A17:4709-4732,2002 · 24 pages, 6 figures, LaTeX. Revised: Complete version. Numerical predictions are improved and the estimate for the decay fraction revised. The theoretical expectations for the decay fraction and the spectrum itself are given on the plots
arxiv created 2002/04/17 · openalex publication_date 2002/11/28 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Measuring the photon energy spectrum in radiative B decays provides essential help for gaining theoretical control over semileptonic B transitions. The hadronic recoil mass distribution in B → X u ℓ ν promises the best environment for determining |V ub |. The theoretical uncertainties are largest in the domain of low values of the lepton pair mass q 2 . Universality relations allow us to describe this domain reliably in terms of the photon spectrum in B → X s + γ. A method is proposed to incorporate 1/m b corrections into this relation. The low-E γ tail in radiative decays is important in the context of extracting |V ub |. We argue that CLEO's recent fit to the spectrum underestimates the fraction of the photon spectrum below 27thinsp;GeV. Potentially significant uncertainties enter in the theoretical evaluation of the integrated end point lepton spectrum or the B → X u ℓ ν width with a too high value of the lower cut on q 2 in alternative approaches to |V ub |.