Semileptonic $B^{-}\to f_0(1710,1500,1370)e^{-}{\bar{\nu }}_e$ decays

We study the semileptonic decays of $B^-\to f_0(1710,,1500,,1370) e^-\bar \nu_e$,inwhichthethree$f_0$statesmixwithglueball,$\bar s s$and$(\bar u u+\bar d d)/\sqrt 2$ states, respectively. By averaging the mixings fitted in the literature, we find that the branching ratios of $B^-\to f_0 e^-\bar \nu_e$are$O(10^{-6})$,$O(10^{-6})$and$O(10^{-5})$, respectively, which can be simultaneously observed in experiments at $B$ factories. The large predicted branching rate for $B^{-}\to f_0(1370)e^{-}{\bar{\nu }}_e$ would provide a clean mode to directly observe the $f_0(1370)$ state.