BABAR untagged B0+B+ (6 q2 bins)
BABAR untagged B0+B+ (12 q2 bins)
Belle untagged B0
Belle hadronic tag B0 and B+
In the first step of the averaging prodcedure, an average q2 spectrum is determined
from the measurements listed above. A plot of the average q2 spectrum can be found here:
The p-value for this average is 0.04.
The total branching fraction is then calculated from the sum of the partial branching fractions in the average q2 spectrum, taking the correlations between q2 bins into account.
|Experiment / Mode||BF [10-4]||Reference|
|Belle had. tag: B+ -> pi0 l+ nu × 2 τ0/τ+||1.48 +/- 0.15 +/- 0.08||Phys. Rev. D88, 032005 (2013) [arXiv:1306.2781 [hep-ex]]|
|Belle had. tag: B0 -> pi- l+ nu||1.49 +/- 0.09 +/- 0.07||Phys. Rev. D88, 032005 (2013) [arXiv:1306.2781 [hep-ex]]|
|BABAR untagged (6 q2 bins): B -> pi l nu||1.41 +/- 0.05 +/- 0.08||Phys. Rev. D83, 032007 (2011) [arXiv:1005.3288v2 [hep/ex]]|
|BABAR untagged (12 q2 bins): B -> pi l nu||1.44 +/- 0.04 +/- 0.06||Phys. Rev. D86, 092004 (2012) [arXiv:1201.1253 [hep/ex]]|
|Belle untagged: B0 -> pi- l+ nu||1.48 +/- 0.04 +/- 0.07||Phys. Rev. D83, 071101 (2011) [arXiv:1012.0090 [hep-ex]]|
|Average: B0 -> pi- l+ nu||1.47 +/- 0.02 +/- 0.06|
|Vub| is determined from a combined fit of a B -> pi form factor parameterization to theory predictions and the average q2 spectrum in data.
The theory input included in the fit are the results from the FLAG lattice average (S. Aoki et al., [arXiv:1203.1359 [hep-ph]]) and the light-cone sum rule result at q2 = 0 GeV2 (A. Bharucha, JHEP 1205 (2012) 092 [arXiv:1203.1359 [hep-ph]]).For the form factor parameterization, we use the BCL parameterization (Bourrely, Caprini and Lellouch, Phys. Rev. D79, 013008 (2009) [arXiv:0807.2722v3 [hep-ph]]) with 3+1 parameters, i.e. 3 parameters for the coefficients b0,b1,b2 in the BCL expansion and one normalization parameter for |Vub|.
The results of the combined fit are:
|Vub| = (3.65 +- 0.09 +- 0.11) × 10-3
b0 = 0.421 +- 0.012
b1 = -0.390 +- 0.033
b2 = -0.650 +- 0.126
The quoted uncertainties on |Vub| are experimental and theoretial, those on the BCL parameters are the combined experimental and theoretical errors obtained from the fit.
The probability of the fit is 0.61.
A plot of the fit result is available here: pdf