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We use Omnes representations of the form factors V, A(1) and A(2) for exclusive semileptonic B -> rho decays, and apply them to combine experimental partial branching fraction information with theoretical calculations of the three form factors to extract vertical bar V-ub vertical bar. We find vertical bar V-ub vertical bar = (2.8 +/- 0.2(stat)+/- 0.5(sys)) x 10(-3). where we have conservatively assumed a 20% systematic error to account for the use of the quenched approximation in the lattice QCD calculations of the form factors. This value of vertical bar V-ub vertical bar is slightly lower than the values extracted from exclusive semileptonic B -> pi decays, (3.47 +/- 0.29 +/- 0.03) x 10(-3) [J.M. Flynn, J. Nieves, Phys. Rev. D 76 (2007) 031302]. (3.36 +/- 0.23) x 10(-3) [C. Bourrely, I. Caprini, L Lellouch, Phys. Rev. D 79 (2009) 013008], (3.38 +/- 0.35) x 10(-3) [J. Bailey, et al., arXiv:0811.3640 [hep-lat]], and using all other inputs in CKM fits, (3.55 +/- 0.15) x 10(-3) [UTfit Collaboration M. Bona, et al., JHEP 0610 (2006) 081. hep-ph/0606167; UTfit Collaboration, http://utfit.romal.infn.it/ckm-results/ckm-results.html]. The disagreement is greater when we compare to the result extracted from inclusive B -> X(u)l nu decays, vertical bar V-ub vertical bar = (4.10 +/- 0.30(exp)+/- 0.29(th)) x 10(-3) [M. Neubert, in: Proceedings of FPCP 2007: 5th Conference on Flavor Physics and CP Violation, Bled, Slovenia, 12-16 May 2007 (2007)].
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