B → (π,η,η) transition form factors are investigated in the covariant light-front approach. With theoretical uncertainties, we find that B → (π,η,η) form factors at q2 = 0 are f (π,η,η) + (0) =(0.245+0.000 -0.001 ± 0.011, 0.220 ± 0.009 ± 0.009, 0.180 ± 0.008+0.008 -0.007) for vector current and f (π,η,η) T (0) =(0.239+0.002+0.020 -0.003-0.018, 0.211 ± 0.009+0.017 -0.015, 0.173 ± 0.007+0.014 -0.013) for tensor current, respectively. With theobtained q2-dependent f π + (q2) and observed branching ratio (BR) for ˉBd → π+ ˉν, the Vub is found as VubLF = (3.99 ± 0.13) × 10-3. As a result, the predicted BRs for ˉB → (η,η) ˉν decays with = e,μ are given by (0.49+0.02+0.10 -0.04-0.07, 0.24+0.01+0.04-0.02-0.03) × 10-4, while the BRs for D- → (η,η) ˉν are (11.1+0.5+0.9 -0.6-0.9, 1.79+0.07+0.12 -0.08-0.12) × 10-4. In addition, we also study the integrated lepton angular asymmetries for ˉB →(π,η,η)τ ˉντ : (0.277+0.001+0.005 -0.001-0.007, 0.290+0.002+0.003 -0.000-0.003, 0.312+0.004+0.005 -0.000-0.006).
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