Abstract
To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vub|, we have re-analyzed all the available inputs (data and theory) on the B → πℓν decays including the newly available inputs on the form-factors from light cone sum rule (LCSR) approach. We have reproduced and compared the results with the procedure taken up by the Heavy Flavor Averaging Group (HFLAV), while commenting on the effect of outliers on the fits. After removing the outliers and creating a comparable group of data-sets, we mention a few scenarios in the extraction of |Vub|. In all those scenarios, the extracted values of |Vub| are higher than that obtained by HFLAV. Our best results for |Vub|exc. are (3.94 ± 0.14) × 10−3 and left({3.93}_{-0.15}^{+0.14}right) × 10−3 in frequentist and Bayesian approaches, respectively, which are consistent with that extracted from inclusive decays |Vub|inc. within 1 σ confidence interval.
Highlights
Order to further make sure of the validity of our results, we have compared this particular case with a fit to the BaBar (12) data alone that has been provided in table VI of the corresponding reference [8] using a BGL expansion for the form factors, the details of which can be obtained from [6] and the references therein
We have extracted |Vub| analyzing all the available inputs on the exclusive B → πlν decays. This includes the data on the partial decay rates, inputs from lattice, and those from light cone sum rule (LCSR)
We have pointed out some of the issues of the earlier fits done by Heavy Flavor Averaging Group (HFLAV), which relied upon obtaining an average q2 spectrum of the partial width generated from all the available data on the decay rates on B → π ν in the first stage
Summary
The differential decay width w.r.t. q2 for a pseudoscalar to pseudoscalar semileptonic decay is a function of f+,0(q2). A few coefficients are needed to represent the form factor accurately It provides a prescription for introducing more parameters with the improvement of data. The BSZ form factor parametrization does not obey the known asymptotic behaviour near the Bπ threshold. (1.4) and (1.5), in the BCL parametrization the same kinematic constraint leads to a complex relationship between the expansion coefficients: b03 = 45.70(b+0 − b00) − 12.78b01 − 3.58b02 + 12.85b+1 + 3.44b+2 + 1.21b+3. Following this equation, we have replaced b03 in terms of the other coefficients in the fit. We will discuss the impact of this difference on the outcome of our analysis
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