Erratum: Model-independent description ofB→πlνdecays and a determination of|Vub|[Phys. Rev. DPR

B→πℓνandBs→Kℓνform factors andFlynn1, Izubuchi2, Kawanai3 et al. 2015Phys. Rev. D

“…Both statistical errors and discretization errors increase at lower q 2 , which corresponds to larger pion/kaon energies. To extend our results beyond the momenta accessible in our simulations, we extrapolate our results to q 2 = 0 using a model-independent z-parameterization based on analyticity and unitarity [24,25]. Our results can be combined with current and future experimental measurements of the experimentally-measured B → π ν and B s → K ν branching fractions to obtain the CKM matrix element |V ub |.…”

“…Therefore, given a suitable change of variables, they can be expressed as a convergent power series (see, e.g., [24,25,[57][58][59][60]). Unitarity and heavy-quark power counting bound the size of the series coefficients.…”

“…In the literature, the new variable is called z, and the class of functions are called z-parameterizations. Two such parameterizations commonly used to extrapolate the B → π ν form factor are by Boyd, Grinstein, and Lebed (BGL) [24] and Bourrely, Caprini, and Lellouch (BCL) [25].…”

“…[25], Bourrely, Caprini, and Lellouch (who only discuss f + ) choose a simpler outer function φ BCL 0 = 1. They also point out that the BGL form-factor parameterization does not obey the known asymptotic behavior near the Bπ production threshold Imf + (q 2 ) ∼ q 2 − t + 3/2 (which is due to angular momentum conservation).…”

Form factors and strong couplings of heavy baryons from QCD light-cone sum rules

“…Since the form factors are only available at q 2 ≤ q 2 max , we apply the conformal mapping q 2 → z and z-series parametrization to extrapolate the form factors to the whole semileptonic region q 2 ≤ (m Λ b − m N ) 2 . More specifically, we use the z-series parametrization in the BCL-version suggested in [37]. The mapping transformation reads:…”