On The Expected Photon Spectrum in B -> X_s + gamma and Its Uses

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dc.creatorBigi, Ikaros
dc.creatorUraltsev, Nikolai
dc.date2002-02-18
dc.date2002-04-17
dc.date.accessioned2026-07-07T11:31:13Z
dc.date.available2026-07-07T11:31:13Z
dc.descriptionMeasuring 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 \ellνpromises 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 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_γtail 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 2 GeV. Potentially significant uncertainties enter in the theoretical evaluation of the integrated end-point lepton spectrum or the B -> X_u \ellνwidth with a too high value of the lower cut on q^2 in alternative approaches to |V_ub|.
dc.description24 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
dc.identifierhttps://arxiv.org/abs/hep-ph/0202175
dc.identifierhttp://arxiv.org/abs/hep-ph/0202175
dc.identifierInt.J.Mod.Phys.A17:4709-4732,2002
dc.identifierdoi:10.1142/S0217751X02010856
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/197194
dc.subjectHigh Energy Physics - Phenomenology
dc.titleOn The Expected Photon Spectrum in B -> X_s + gamma and Its Uses
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