We show the phenomenological AC2M2 ansatz to be consistent with QCD through order 1/mb in the description of B → lvl + Xu and B → γ + Xs transitions, including their energy spectra and differential distributions. This suggests a concrete realization of the QCD distribution function, which we call the "Roman" function. Yet the AC2M2 description of the end-point domain in B → lvl + Xc is, formally speaking, incompatible with QCD: a different distribution function enters the description of b → c decays as compared to the transitions to massless quarks. The intrinsic limitation of the AC2M2 model could reveal itself in different values of the effective b quark mass from fits of the Λb and B decays.
|Original language||English (US)|
|Number of pages||10|
|Journal||Physics Letters B|
|State||Published - Jun 2 1994|
Bibliographical noteFunding Information:
We thank G. Altarelli for his thoughtful comments on the manuscript. N.U. acknowledges interesting discussions with T. Mannel and is grateful to D. Cassel for his interest. M.S. and A.V. are grateful to R. Polling and M. Voloshin for useful comments. We are also indebted to R. Mountain for producing the figures. This work was supported in part by the National Science Foundation under the grant number PHY 92-13313 and by DOE under the grant number DOE-AC02-83ER40105.