B→ρlν decay and |Vub|

B→ρlν decay is analyzed in the effective theory of heavy quark with infinite mass limit. The matrix element relevant to the heavy to light vector meson semileptonic decays is parametrized by a set of four heavy flavor-spin independent universal wave functions at the leading order of effective theory. The form factors are calculated at the leading 1/mQ order using the light cone sum rule method in the framework of effective theory. |Vub| is then extracted via B→ρlν decay mode.