|Vᵤb| and Constraints on the Leading-Twist Pion Distribution Amplitude from B->pi l nu

الأصل · EN

Using new experimental data on the leptonic mass spectrum of B->pi l nu, we simultaneously determine |Vᵤb| and constrain a₂ᵖi and a₄ᵖi, the first two Gegenbauer moments of the pion's leading-twist distribution amplitude. We find |Vᵤb| = (3.2± 0.1± 0.1± 0.3) 10-3, where the first error is experimental, the second comes from the shape of the form factor in q² and the third is a 8% uncertainty from the normalisation of the form factor. We also find a₂ᵖi(1 GeV)=0.19± 0.19 and a₄ᵖi(1 GeV)≥ -0.07.