Measuring of | Vub| of the forthcoming decade

Abstract

I first introduce the importance of measuring V ub precisely. Then, from a theoretician's point of view, I review (a) past history, (b) present trials, and (c) possible future alternatives on measuring | V ub | and/or | V ub V cb | . As of my main topic, I introduce a model-independent method, which predicts Γ(B → X ulν)/Γ(B → X clν) ≡ (γ u/γ c) × |V ub/V cb| 2 ⋍ (1.83 ± 0.28) × |V ub/V cb| ≡ (γ c/γ u) 1 2 × [β(B → X ulν)/β(B → X clν)] 1 2 ⋍ (0.74 ± 0.06) × [β(B → X ulν)/β(B → X clν)] 1 2 , based on the heavy quark effective theory. I also explore the possible experimental options separate B → X u lν from the dominant B → X c lν: the measurement of inclusive hadronic invariant mass distributions, and the ‘ D − τ’ (and ‘K − π’) separation conditions. I also clarify the relevant experimental backgrounds.