I first introduce the importance of measuring Vub precisely. Then, from a theoretician's point of view, I review (a) past history, (b) present trials, and (c) possible future alternatives on measuring \Vub/ and/or |Vub/Vcb. As of my main topic, I introduce a model-independent method, which predicts Γ(B → Xulν)/Γ(B → Xclν) ≡ (γ/γc) × |Vub/Vcb|2 ≃ (1.83±0.28) × |Vub/Vcb\2 and \Vub/Vcb\ ≡ (γc/γu)1/2 × [B(B → Xulν)/B(B → Xclν)]1/2 ≃ (0.74 ± 0.06) × [B(B → Xulν)/B(B → Xclν)]1/2, based on the heavy quark effective theory. I also explore the possible experimental options to separate B → Xulν from the dominant B → Xclν: the measurement of inclusive hadronic invariant mass distributions, and the 'D - π' (and 'K - π') separation conditions. I also clarify the relevant experimental backgrounds.
Bibliographical noteFunding Information:
*Present address till Feb. 1997: Theory Division, KEK, Tsukuba, Ibaraki 305, Japan. The work was supported in part by the KOSEF, Project No. 951-0207-0P08-2, in part by the BSRI Program, Project No. BSRI-97-2425, in part by CTP of SNU, and in part by the COE fellowship of Japanese Government.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics