Determining |Vub| from the B→ Xᵤℓν dilepton invariant mass spectrum

الأصل · EN

The invariant mass spectrum of the lepton pair in inclusive semileptonic B→ Xᵤ ℓν decay yields a model independent determination of |Vub|. Unlike the lepton energy and hadronic invariant mass spectra, nonperturbative effects are only important in the resonance region, and play a parametrically suppressed role when dΓ/ dq² is integrated over q² > (mB-mD)², which is required to eliminate the B→ Xc ℓν background. We discuss these backgrounds for q² slightly below (mB-mD)², and point out that instead of q² > (mB-mD)² = 11.6 GeV², the cut can be lowered to q² 10.5 GeV². This is important experimentally, particularly when effects of a finite neutrino reconstruction resolution are included.