Form factors from light-cone sum rules with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi></mml:math>-meson distribution amplitudes

New sum rules for $B\ensuremath{\rightarrow}\ensuremath{\pi},K$ and $B\ensuremath{\rightarrow}\ensuremath{\rho},{K}^{*}$ form factors are derived from the correlation functions expanded near the light cone in terms of $B$-meson distribution amplitudes. The contributions of quark-antiquark and quark-antiquark-gluon components in the $B$ meson are taken into account. Models for the $B$-meson three-particle distribution amplitudes are suggested, based on QCD sum rules in heavy-quark effective theory. Employing the new light-cone sum rules, we calculate the form factors at small momentum transfers, including $SU(3)$-violation effects. The results agree with the predictions of the conventional light-cone sum rules.