SEARCH FOR B~+ → l~+ v_e AND B~+ → l~+ v_eγ DECAYS

摘要

We have searched for the leptonic and radiative leptonic B decays, B~+ → τ~+ v_τ, B~+ → μ~+ v_μ, B~+ → e~+ v_e γ and B~+ → μ~+ v_μγ. Using a 140 fb~(-1) data sample collected with the Belle detector at the KEKB asymmetric e~+e~- collider, we find no evidence for signals in any mode and set the following preliminary upper limits at 90% confidence level: B(B~+ → τ~+ v_τ) < 2.9 x 10~(-4), B(B~+ → μ~+ v_μ) < 2.0 x 10~(-6), B(B~+ → e~+ V_eγ) < 2.2 x 10~(-5) and B(B~+ → μ~+ v_μ?) < 2.3 x 10~(-5).